text: /*
    This is a version (aka dlmalloc) of malloc/free/realloc written by
    Doug Lea and released to the public domain.  Use, modify, and
    redistribute this code without permission or acknowledgement in any
    way you wish.  Send questions, comments, complaints, performance
    data, etc to dl@cs.oswego.edu
  
  * VERSION 2.7.0 Sun Mar 11 14:14:06 2001  Doug Lea  (dl at gee)
  
     Note: There may be an updated version of this malloc obtainable at
             ftp://gee.cs.oswego.edu/pub/misc/malloc.c
           Check before installing!
  
  * Quickstart
  
    This library is all in one file to simplify the most common usage:
    ftp it, compile it (-O), and link it into another program. All
    of the compile-time options default to reasonable values for use on
    most unix platforms. Compile -DWIN32 for reasonable defaults on windows.
    You might later want to step through various compile-time and dynamic
    tuning options.
  
    For convenience, an include file for code using this malloc is at:
       ftp://gee.cs.oswego.edu/pub/misc/malloc-2.7.0.h
    You don't really need this .h file unless you call functions not
    defined in your system include files.  The .h file contains only the
    excerpts from this file needed for using this malloc on ANSI C/C++
    systems, so long as you haven't changed compile-time options about
    naming and tuning parameters.  If you do, then you can create your
    own malloc.h that does include all settings by cutting at the point
    indicated below.
  
  * Why use this malloc?
  
    This is not the fastest, most space-conserving, most portable, or
    most tunable malloc ever written. However it is among the fastest
    while also being among the most space-conserving, portable and tunable.
    Consistent balance across these factors results in a good general-purpose
    allocator for malloc-intensive programs.
  
    The main properties of the algorithms are:
    * For large (>= 512 bytes) requests, it is a pure best-fit allocator,
      with ties normally decided via FIFO (i.e. least recently used).
    * For small (<= 64 bytes by default) requests, it is a caching
      allocator, that maintains pools of quickly recycled chunks.
    * In between, and for combinations of large and small requests, it does
      the best it can trying to meet both goals at once.
    * For very large requests (>= 128KB by default), it relies on system
      memory mapping facilities, if supported.
  
    For a longer but slightly out of date high-level description, see
       http://gee.cs.oswego.edu/dl/html/malloc.html
  
    You may already by default be using a C library containing a malloc
    that is  based on some version of this malloc (for example in
    linux). You might still want to use the one in this file in order to
    customize settings or to avoid overheads associated with library
    versions.
  
  * Contents, described in more detail in "description of public routines" below.
  
    Standard (ANSI/SVID/...)  functions:
      malloc(size_t n);
      calloc(size_t n_elements, size_t element_size);
      free(Void_t* p);
      realloc(Void_t* p, size_t n);
      memalign(size_t alignment, size_t n);
      valloc(size_t n);
      mallinfo()
      mallopt(int parameter_number, int parameter_value)
  
    Additional functions:
      independent_calloc(size_t n_elements, size_t size, Void_t* chunks[]);
      independent_comalloc(size_t n_elements, size_t sizes[], Void_t* chunks[]);
      pvalloc(size_t n);
      cfree(Void_t* p);
      malloc_trim(size_t pad);
      malloc_usable_size(Void_t* p);
      malloc_stats();
  
  * Vital statistics:
  
    Supported pointer representation:       4 or 8 bytes
    Supported size_t  representation:       4 or 8 bytes 
         Note that size_t is allowed to be 4 bytes even if pointers are 8.
         You can adjust this by defining INTERNAL_SIZE_T
  
    Alignment:                              2 * sizeof(size_t) (default)
         (i.e., 8 byte alignment with 4byte size_t). This suffices for
         nearly all current machines and C compilers. However, you can
         define MALLOC_ALIGNMENT to be wider than this if necessary.
  
    Minimum overhead per allocated chunk:   4 or 8 bytes
         Each malloced chunk has a hidden word of overhead holding size
         and status information.
  
    Minimum allocated size: 4-byte ptrs:  16 bytes    (including 4 overhead)
                            8-byte ptrs:  24/32 bytes (including, 4/8 overhead)
  
         When a chunk is freed, 12 (for 4byte ptrs) or 20 (for 8 byte
         ptrs but 4 byte size) or 24 (for 8/8) additional bytes are
         needed; 4 (8) for a trailing size field and 8 (16) bytes for
         free list pointers. Thus, the minimum allocatable size is
         16/24/32 bytes.
  
         Even a request for zero bytes (i.e., malloc(0)) returns a
         pointer to something of the minimum allocatable size.
  
         The maximum overhead wastage (i.e., number of extra bytes
         allocated than were requested in malloc) is less than or equal
         to the minimum size, except for requests >= mmap_threshold that
         are serviced via mmap(), where the worst case wastage is 2 *
         sizeof(size_t) bytes plus the remainder from a system page (the
         minimal mmap unit); typically 4096 or 8192 bytes.
  
    Maximum allocated size:  4-byte size_t: 2^32 minus about two pages 
                             8-byte size_t: 2^64 minus about two pages
  
         It is assumed that (possibly signed) size_t values suffice to
         represent chunk sizes. `Possibly signed' is due to the fact
         that `size_t' may be defined on a system as either a signed or
         an unsigned type. The ISO C standard says that it must be
         unsigned, but a few systems are known not to adhere to this.
         Additionally, even when size_t is unsigned, sbrk (which is by
         default used to obtain memory from system) accepts signed
         arguments, and may not be able to handle size_t-wide arguments
         with negative sign bit.  Generally, values that would
         appear as negative after accounting for overhead and alignment
         are supported only via mmap(), which does not have this
         limitation.
  
         Requests for sizes outside the allowed range will perform an optional
         failure action and then return null. (Requests may also
         also fail because a system is out of memory.)
  
    Thread-safety: NOT thread-safe unless USE_MALLOC_LOCK defined
  
         When USE_MALLOC_LOCK is defined, wrappers are created to
         surround every public call with either a pthread mutex or
         a win32 spinlock (depending on WIN32). This is not
         especially fast, and can be a major bottleneck.
         It is designed only to provide minimal protection
         in concurrent environments, and to provide a basis for
         extensions.  If you are using malloc in a concurrent program,
         you would be far better off obtaining ptmalloc, which is
         derived from a version of this malloc, and is well-tuned for
         concurrent programs. (See http://www.malloc.de)
  
    Compliance: I believe it is compliant with the 1997 Single Unix Specification
         (See http://www.opennc.org). Also SVID/XPG, ANSI C, and probably 
         others as well.
  
  * Synopsis of compile-time options:
  
      People have reported using previous versions of this malloc on all
      versions of Unix, sometimes by tweaking some of the defines
      below. It has been tested most extensively on Solaris and
      Linux. It is also reported to work on WIN32 platforms.
      People also report using it in stand-alone embedded systems.
  
      The implementation is in straight, hand-tuned ANSI C.  It is not
      at all modular. (Sorry!)  It uses a lot of macros.  To be at all
      usable, this code should be compiled using an optimizing compiler
      (for example gcc -O3) that can simplify expressions and control
      paths. (FAQ: some macros import variables as arguments rather than
      declare locals because people reported that some debuggers
      otherwise get confused.)
  
      OPTION                     DEFAULT VALUE
  
      Compilation Environment options:
  
      __STD_C                    derived from C compiler defines
      WIN32                      NOT defined
      HAVE_MEMCPY                defined
      USE_MEMCPY                 1 if HAVE_MEMCPY is defined
      HAVE_MMAP                  defined as 1 
      MMAP_CLEARS                1
      HAVE_MREMAP                0 unless linux defined
      malloc_getpagesize         derived from system #includes, or 4096 if not
      HAVE_USR_INCLUDE_MALLOC_H  NOT defined
      LACKS_UNISTD_H             NOT defined unless WIN32
      LACKS_SYS_PARAM_H          NOT defined unless WIN32
      LACKS_SYS_MMAN_H           NOT defined unless WIN32
  
      Changing default word sizes:
  
      INTERNAL_SIZE_T            size_t
      MALLOC_ALIGNMENT           2 * sizeof(INTERNAL_SIZE_T)
  
      Configuration and functionality options:
  
      USE_DL_PREFIX              NOT defined
      USE_PUBLIC_MALLOC_WRAPPERS NOT defined
      USE_MALLOC_LOCK            NOT defined
      DEBUG                      NOT defined
      REALLOC_ZERO_BYTES_FREES   NOT defined
      MALLOC_FAILURE_ACTION      errno = ENOMEM, if __STD_C defined, else no-op
      TRIM_FASTBINS              0
  
      Options for customizing MORECORE:
  
      MORECORE                   sbrk
      MORECORE_CONTIGUOUS        1 
      MORECORE_CANNOT_TRIM       NOT defined
      MMAP_AS_MORECORE_SIZE      (1024 * 1024) 
  
      Tuning options that are also dynamically changeable via mallopt:
  
      DEFAULT_MXFAST             64
      DEFAULT_TRIM_THRESHOLD     128 * 1024
      DEFAULT_TOP_PAD            0
      DEFAULT_MMAP_THRESHOLD     128 * 1024
      DEFAULT_MMAP_MAX           65536
  
      There are several other #defined constants and macros that you
      probably don't want to touch unless you are extending or adapting malloc.
  */
  
  /* tu: we must be thread-safe. */
  #define USE_MALLOC_LOCK
  /* tu: prefix the malloc functions.  MSVC has problems otherwise... */
  #define USE_DL_PREFIX
  
  
  /*
    WIN32 sets up defaults for MS environment and compilers.
    Otherwise defaults are for unix.
  */
  
  /* #define WIN32 */
  
  #ifdef WIN32
  
  #pragma warning(disable: 4308 4307 4047)  // @@ tulrich
  
  #define WIN32_LEAN_AND_MEAN
  #include <windows.h>
  
  /* Win32 doesn't supply or need the following headers */
  #define LACKS_UNISTD_H
  #define LACKS_SYS_PARAM_H
  #define LACKS_SYS_MMAN_H
  
  /* Use the supplied emulation of sbrk */
  #define MORECORE sbrk
  #define MORECORE_CONTIGUOUS 1
  #define MORECORE_FAILURE    ((void*)(-1))
  
  /* Use the supplied emulation of mmap and munmap */
  #define HAVE_MMAP 1
  #define MUNMAP_FAILURE  (-1)
  #define MMAP_CLEARS 1
  
  /* These values don't really matter in windows mmap emulation */
  #define MAP_PRIVATE 1
  #define MAP_ANONYMOUS 2
  #define PROT_READ 1
  #define PROT_WRITE 2
  
  /* Emulation functions defined at the end of this file */
  
  /* If USE_MALLOC_LOCK, use supplied critical-section-based lock functions */
  #ifdef USE_MALLOC_LOCK
  static int slwait(int *sl);
  static int slrelease(int *sl);
  #endif
  
  static long getpagesize(void);
  static long getregionsize(void);
  static void *sbrk(long size);
  static void *mmap(void *ptr, long size, long prot, long type, long handle, long arg);
  static long munmap(void *ptr, long size);
  
  static void vminfo (unsigned long *free, unsigned long *reserved, unsigned long *committed);
  static int cpuinfo (int whole, unsigned long *kernel, unsigned long *user);
  
  #endif
  
  /*
    __STD_C should be nonzero if using ANSI-standard C compiler, a C++
    compiler, or a C compiler sufficiently close to ANSI to get away
    with it.
  */
  
  #ifndef __STD_C
  #if defined(__STDC__) || defined(_cplusplus)
  #define __STD_C     1
  #else
  #define __STD_C     0
  #endif 
  #endif /*__STD_C*/
  
  
  /*
    Void_t* is the pointer type that malloc should say it returns
  */
  
  #ifndef Void_t
  #if (__STD_C || defined(WIN32))
  #define Void_t      void
  #else
  #define Void_t      char
  #endif
  #endif /*Void_t*/
  
  #if __STD_C
  #include <stddef.h>   /* for size_t */
  #else
  #include <sys/types.h>
  #endif
  
  #ifdef __cplusplus
  extern "C" {
  #endif
  
  /* define LACKS_UNISTD_H if your system does not have a <unistd.h>. */
  
  /* #define  LACKS_UNISTD_H */
  
  #ifndef LACKS_UNISTD_H
  #include <unistd.h>
  #endif
  
  /* define LACKS_SYS_PARAM_H if your system does not have a <sys/param.h>. */
  
  /* #define  LACKS_SYS_PARAM_H */
  
  
  #include <stdio.h>    /* needed for malloc_stats */
  #include <errno.h>    /* needed for optional MALLOC_FAILURE_ACTION */
  
  
  /*
    Debugging:
  
    Because freed chunks may be overwritten with bookkeeping fields, this
    malloc will often die when freed memory is overwritten by user
    programs.  This can be very effective (albeit in an annoying way)
    in helping track down dangling pointers.
  
    If you compile with -DDEBUG, a number of assertion checks are
    enabled that will catch more memory errors. You probably won't be
    able to make much sense of the actual assertion errors, but they
    should help you locate incorrectly overwritten memory.  The
    checking is fairly extensive, and will slow down execution
    noticeably. Calling malloc_stats or mallinfo with DEBUG set will
    attempt to check every non-mmapped allocated and free chunk in the
    course of computing the summmaries. (By nature, mmapped regions
    cannot be checked very much automatically.)
  
    Setting DEBUG may also be helpful if you are trying to modify
    this code. The assertions in the check routines spell out in more
    detail the assumptions and invariants underlying the algorithms.
  
    Setting DEBUG does NOT provide an automated mechanism for checking
    that all accesses to malloced memory stay within their
    bounds. However, there are several add-ons and adaptations of this
    or other mallocs available that do this.
  */
  
  #if DEBUG
  #include <assert.h>
  #else
  #define assert(x) ((void)0)
  #endif
  
  
  /*
    INTERNAL_SIZE_T is the word-size used for internal bookkeeping
    of chunk sizes.
  
    The default version is the same as size_t.
  
    While not strictly necessary, it is best to define this as an
    unsigned type, even if size_t is a signed type. This may avoid some
    artificial size limitations on some systems.
  
    On a 64-bit machine, you may be able to reduce malloc overhead by
    defining INTERNAL_SIZE_T to be a 32 bit `unsigned int' at the
    expense of not being able to handle more than 2^32 of malloced
    space. If this limitation is acceptable, you are encouraged to set
    this unless you are on a platform requiring 16byte alignments. In
    this case the alignment requirements turn out to negate any
    potential advantages of decreasing size_t word size.
  
    Implementors: Beware of the possible combinations of:
       - INTERNAL_SIZE_T might be signed or unsigned, might be 32 or 64 bits,
         and might be the same width as int or as long
       - size_t might have different width and signedness as INTERNAL_SIZE_T
       - int and long might be 32 or 64 bits, and might be the same width
    To deal with this, most comparisons and difference computations
    among INTERNAL_SIZE_Ts should cast them to unsigned long, being
    aware of the fact that casting an unsigned int to a wider long does
    not sign-extend. (This also makes checking for negative numbers
    awkward.) Some of these casts result in harmless compiler warnings
    on some systems.
  */
  
  #ifndef INTERNAL_SIZE_T
  #define INTERNAL_SIZE_T size_t
  #endif
  
  /* The corresponding word size */
  #define SIZE_SZ                (sizeof(INTERNAL_SIZE_T))
  
  
  /*
    MALLOC_ALIGNMENT is the minimum alignment for malloc'ed chunks.
    It must be a power of two at least 2 * SIZE_SZ, even on machines
    for which smaller alignments would suffice. It may be defined as
    larger than this though. Note however that code and data structures
    are optimized for the case of 8-byte alignment.
  */
  
  
  #ifndef MALLOC_ALIGNMENT
  #define MALLOC_ALIGNMENT       (2 * SIZE_SZ)
  #endif
  
  /* The corresponding bit mask value */
  #define MALLOC_ALIGN_MASK      (MALLOC_ALIGNMENT - 1)
  
  
  
  /*
    REALLOC_ZERO_BYTES_FREES should be set if a call to
    realloc with zero bytes should be the same as a call to free.
    Some people think it should. Otherwise, since this malloc
    returns a unique pointer for malloc(0), so does realloc(p, 0).
  */
  
  /*   #define REALLOC_ZERO_BYTES_FREES */
  
  /*
    TRIM_FASTBINS controls whether free() of a very small chunk can
    immediately lead to trimming. Setting to true (1) can reduce memory
    footprint, but will almost always slow down programs that use a lot
    of small chunks.
  
    Define this only if you are willing to give up some speed to more
    aggressively reduce system-level memory footprint when releasing
    memory in programs that use many small chunks.  You can get
    essentially the same effect by setting MXFAST to 0, but this can
    lead to even greater slowdowns in programs using many small chunks.
    TRIM_FASTBINS is an in-between compile-time option, that disables
    only those chunks bordering topmost memory from being placed in
    fastbins.
  */
  
  #ifndef TRIM_FASTBINS
  #define TRIM_FASTBINS  0
  #endif
  
  
  /*
    USE_DL_PREFIX will prefix all public routines with the string 'dl'.
    This is necessary when you only want to use this malloc in one part 
    of a program, using your regular system malloc elsewhere.
  */
  
  /* #define USE_DL_PREFIX */
  
  
  /*
    USE_MALLOC_LOCK causes wrapper functions to surround each
    callable routine with pthread mutex lock/unlock.
  
    USE_MALLOC_LOCK forces USE_PUBLIC_MALLOC_WRAPPERS to be defined
  */
  
  
  /* #define USE_MALLOC_LOCK */
  
  
  /*
    If USE_PUBLIC_MALLOC_WRAPPERS is defined, every public routine is
    actually a wrapper function that first calls MALLOC_PREACTION, then
    calls the internal routine, and follows it with
    MALLOC_POSTACTION. This is needed for locking, but you can also use
    this, without USE_MALLOC_LOCK, for purposes of interception,
    instrumentation, etc. It is a sad fact that using wrappers often
    noticeably degrades performance of malloc-intensive programs.
  */
  
  #ifdef USE_MALLOC_LOCK
  #define USE_PUBLIC_MALLOC_WRAPPERS
  #else
  /* #define USE_PUBLIC_MALLOC_WRAPPERS */
  #endif
  
  
  /* 
     Two-phase name translation.
     All of the actual routines are given mangled names.
     When wrappers are used, they become the public callable versions.
     When DL_PREFIX is used, the callable names are prefixed.
  */
  
  #ifndef USE_PUBLIC_MALLOC_WRAPPERS
  #define cALLOc      public_cALLOc
  #define fREe        public_fREe
  #define cFREe       public_cFREe
  #define mALLOc      public_mALLOc
  #define mEMALIGn    public_mEMALIGn
  #define rEALLOc     public_rEALLOc
  #define vALLOc      public_vALLOc
  #define pVALLOc     public_pVALLOc
  #define mALLINFo    public_mALLINFo
  #define mALLOPt     public_mALLOPt
  #define mTRIm       public_mTRIm
  #define mSTATs      public_mSTATs
  #define mUSABLe     public_mUSABLe
  #define iCALLOc     public_iCALLOc
  #define iCOMALLOc   public_iCOMALLOc
  #endif
  
  #ifdef USE_DL_PREFIX
  #define public_cALLOc    dlcalloc
  #define public_fREe      dlfree
  #define public_cFREe     dlcfree
  #define public_mALLOc    dlmalloc
  #define public_mEMALIGn  dlmemalign
  #define public_rEALLOc   dlrealloc
  #define public_vALLOc    dlvalloc
  #define public_pVALLOc   dlpvalloc
  #define public_mALLINFo  dlmallinfo
  #define public_mALLOPt   dlmallopt
  #define public_mTRIm     dlmalloc_trim
  #define public_mSTATs    dlmalloc_stats
  #define public_mUSABLe   dlmalloc_usable_size
  #define public_iCALLOc   dlindependent_calloc
  #define public_iCOMALLOc dlindependent_comalloc
  #else /* USE_DL_PREFIX */
  #define public_cALLOc    calloc
  #define public_fREe      free
  #define public_cFREe     cfree
  #define public_mALLOc    malloc
  #define public_mEMALIGn  memalign
  #define public_rEALLOc   realloc
  #define public_vALLOc    valloc
  #define public_pVALLOc   pvalloc
  #define public_mALLINFo  mallinfo
  #define public_mALLOPt   mallopt
  #define public_mTRIm     malloc_trim
  #define public_mSTATs    malloc_stats
  #define public_mUSABLe   malloc_usable_size
  #define public_iCALLOc   independent_calloc
  #define public_iCOMALLOc independent_comalloc
  #endif /* USE_DL_PREFIX */
  
  
  /*
    HAVE_MEMCPY should be defined if you are not otherwise using
    ANSI STD C, but still have memcpy and memset in your C library
    and want to use them in calloc and realloc. Otherwise simple
    macro versions are defined below.
  
    USE_MEMCPY should be defined as 1 if you actually want to
    have memset and memcpy called. People report that the macro
    versions are faster than libc versions on some systems.
    
    Even if USE_MEMCPY is set to 1, loops to copy/clear small chunks
    (of <= 36 bytes) are manually unrolled in realloc and calloc.
  */
  
  #define HAVE_MEMCPY
  
  #ifndef USE_MEMCPY
  #ifdef HAVE_MEMCPY
  #define USE_MEMCPY 1
  #else
  #define USE_MEMCPY 0
  #endif
  #endif
  
  
  #if (__STD_C || defined(HAVE_MEMCPY))
  
  #ifdef WIN32
  /* On Win32 memset and memcpy are already declared in windows.h */
  #else
  #if __STD_C
  void* memset(void*, int, size_t);
  void* memcpy(void*, const void*, size_t);
  #else
  Void_t* memset();
  Void_t* memcpy();
  #endif
  #endif
  #endif
  
  /*
    MALLOC_FAILURE_ACTION is the action to take before "return 0" when
    malloc fails to be able to return memory, either because memory is
    exhausted or because of illegal arguments.
    
    By default, sets errno if running on STD_C platform, else does nothing.  
  */
  
  #ifndef MALLOC_FAILURE_ACTION
  #if __STD_C
  #define MALLOC_FAILURE_ACTION \
     errno = ENOMEM;
  
  #else
  #define MALLOC_FAILURE_ACTION
  #endif
  #endif
  
  /*
    MORECORE-related declarations. By default, rely on sbrk
  */
  
  
  #ifdef LACKS_UNISTD_H
  #if !defined(__FreeBSD__) && !defined(__OpenBSD__) && !defined(__NetBSD__)
  #if __STD_C
  extern Void_t*     sbrk(ptrdiff_t);
  #else
  extern Void_t*     sbrk();
  #endif
  #endif
  #endif
  
  /*
    MORECORE is the name of the routine to call to obtain more memory
    from the system.  See below for general guidance on writing
    alternative MORECORE functions, as well as a version for WIN32 and a
    sample version for pre-OSX macos.
  */
  
  #ifndef MORECORE
  #define MORECORE sbrk
  #endif
  
  /*
    MORECORE_FAILURE is the value returned upon failure of MORECORE
    as well as mmap. Since it cannot be an otherwise valid memory address,
    and must reflect values of standard sys calls, you probably ought not
    try to redefine it.
  */
  
  #ifndef MORECORE_FAILURE
  #define MORECORE_FAILURE (-1)
  #endif
  
  /*
    If MORECORE_CONTIGUOUS is true, take advantage of fact that
    consecutive calls to MORECORE with positive arguments always return
    contiguous increasing addresses.  This is true of unix sbrk.  Even
    if not defined, when regions happen to be contiguous, malloc will
    permit allocations spanning regions obtained from different
    calls. But defining this when applicable enables some stronger
    consistency checks and space efficiencies.
  */
  
  #ifndef MORECORE_CONTIGUOUS
  #define MORECORE_CONTIGUOUS 1
  #endif
  
  /*
    Define MORECORE_CANNOT_TRIM if your version of MORECORE
    cannot release space back to the system when given negative
    arguments. This is generally necessary only if you are using
    a hand-crafted MORECORE function that cannot handle negative arguments.
  */
  
  /* #define MORECORE_CANNOT_TRIM */
  
  
  /*
    Define HAVE_MMAP as true to optionally make malloc() use mmap() to
    allocate very large blocks.  These will be returned to the
    operating system immediately after a free(). Also, if mmap
    is available, it is used as a backup strategy in cases where
    MORECORE fails to provide space from system.
  
    This malloc is best tuned to work with mmap for large requests.
    If you do not have mmap, operations involving very large chunks (1MB
    or so) may be slower than you'd like.
  */
  
  #ifndef HAVE_MMAP
  #define HAVE_MMAP 1
  
  /* 
     Standard unix mmap using /dev/zero clears memory so calloc doesn't
     need to.
  */
  
  #ifndef MMAP_CLEARS
  #define MMAP_CLEARS 1
  #endif
  
  #else /* no mmap */
  #ifndef MMAP_CLEARS
  #define MMAP_CLEARS 0
  #endif
  #endif
  
  
  /* 
     MMAP_AS_MORECORE_SIZE is the minimum mmap size argument to use if
     sbrk fails, and mmap is used as a backup (which is done only if
     HAVE_MMAP).  The value must be a multiple of page size.  This
     backup strategy generally applies only when systems have "holes" in
     address space, so sbrk cannot perform contiguous expansion, but
     there is still space available on system.  On systems for which
     this is known to be useful (i.e. most linux kernels), this occurs
     only when programs allocate huge amounts of memory.  Between this,
     and the fact that mmap regions tend to be limited, the size should
     be large, to avoid too many mmap calls and thus avoid running out
     of kernel resources.
  */
  
  #ifndef MMAP_AS_MORECORE_SIZE
  #define MMAP_AS_MORECORE_SIZE (1024 * 1024)
  #endif
  
  /*
    Define HAVE_MREMAP to make realloc() use mremap() to re-allocate
    large blocks.  This is currently only possible on Linux with
    kernel versions newer than 1.3.77.
  */
  
  #ifndef HAVE_MREMAP
  #ifdef linux
  #define HAVE_MREMAP 1
  #else
  #define HAVE_MREMAP 0
  #endif
  
  #endif /* HAVE_MMAP */
  
  
  /*
    The system page size. To the extent possible, this malloc manages
    memory from the system in page-size units.  Note that this value is
    cached during initialization into a field of malloc_state. So even
    if malloc_getpagesize is a function, it is only called once.
  
    The following mechanics for getpagesize were adapted from bsd/gnu
    getpagesize.h. If none of the system-probes here apply, a value of
    4096 is used, which should be OK: If they don't apply, then using
    the actual value probably doesn't impact performance.
  */
  
  
  #ifndef malloc_getpagesize
  
  #ifndef LACKS_UNISTD_H
  #  include <unistd.h>
  #endif
  
  #  ifdef _SC_PAGESIZE         /* some SVR4 systems omit an underscore */
  #    ifndef _SC_PAGE_SIZE
  #      define _SC_PAGE_SIZE _SC_PAGESIZE
  #    endif
  #  endif
  
  #  ifdef _SC_PAGE_SIZE
  #    define malloc_getpagesize sysconf(_SC_PAGE_SIZE)
  #  else
  #    if defined(BSD) || defined(DGUX) || defined(HAVE_GETPAGESIZE)
         extern size_t getpagesize();
  #      define malloc_getpagesize getpagesize()
  #    else
  #      ifdef WIN32 /* use supplied emulation of getpagesize */
  #        define malloc_getpagesize getpagesize() 
  #      else
  #        ifndef LACKS_SYS_PARAM_H
  #          include <sys/param.h>
  #        endif
  #        ifdef EXEC_PAGESIZE
  #          define malloc_getpagesize EXEC_PAGESIZE
  #        else
  #          ifdef NBPG
  #            ifndef CLSIZE
  #              define malloc_getpagesize NBPG
  #            else
  #              define malloc_getpagesize (NBPG * CLSIZE)
  #            endif
  #          else
  #            ifdef NBPC
  #              define malloc_getpagesize NBPC
  #            else
  #              ifdef PAGESIZE
  #                define malloc_getpagesize PAGESIZE
  #              else /* just guess */
  #                define malloc_getpagesize (4096) 
  #              endif
  #            endif
  #          endif
  #        endif
  #      endif
  #    endif
  #  endif
  #endif
  
  /*
    This version of malloc supports the standard SVID/XPG mallinfo
    routine that returns a struct containing usage properties and
    statistics. It should work on any SVID/XPG compliant system that has
    a /usr/include/malloc.h defining struct mallinfo. (If you'd like to
    install such a thing yourself, cut out the preliminary declarations
    as described above and below and save them in a malloc.h file. But
    there's no compelling reason to bother to do this.)
  
    The main declaration needed is the mallinfo struct that is returned
    (by-copy) by mallinfo().  The SVID/XPG malloinfo struct contains a
    bunch of field that are not even meaningful in this version of
    malloc.  These fields are are instead filled by mallinfo() with
    other numbers that might be of interest.
  
    HAVE_USR_INCLUDE_MALLOC_H should be set if you have a
    /usr/include/malloc.h file that includes a declaration of struct
    mallinfo.  If so, it is included; else an SVID2/XPG2 compliant
    version is declared below.  These must be precisely the same for
    mallinfo() to work.  The original SVID version of this struct,
    defined on most systems with mallinfo, declares all fields as
    ints. But some others define as unsigned long. If your system
    defines the fields using a type of different width than listed here,
    you must #include your system version and #define
    HAVE_USR_INCLUDE_MALLOC_H.
  */
  
  /* #define HAVE_USR_INCLUDE_MALLOC_H */
  
  #ifdef HAVE_USR_INCLUDE_MALLOC_H
  #include "/usr/include/malloc.h"
  #else
  
  /* SVID2/XPG mallinfo structure */
  
  struct mallinfo {
    int arena;    /* non-mmapped space allocated from system */
    int ordblks;  /* number of free chunks */
    int smblks;   /* number of fastbin blocks */
    int hblks;    /* number of mmapped regions */
    int hblkhd;   /* space in mmapped regions */
    int usmblks;  /* maximum total allocated space */
    int fsmblks;  /* space available in freed fastbin blocks */
    int uordblks; /* total allocated space */
    int fordblks; /* total free space */
    int keepcost; /* top-most, releasable (via malloc_trim) space */
  };
  
  /*
    SVID/XPG defines four standard parameter numbers for mallopt,
    normally defined in malloc.h.  Only one of these (M_MXFAST) is used
    in this malloc. The others (M_NLBLKS, M_GRAIN, M_KEEP) don't apply,
    so setting them has no effect. But this malloc also supports other
    options in mallopt described below.
  */
  #endif
  
  
  /* ---------- description of public routines ------------ */
  
  /*
    malloc(size_t n)
    Returns a pointer to a newly allocated chunk of at least n bytes, or null
    if no space is available. Additionally, on failure, errno is
    set to ENOMEM on ANSI C systems.
  
    If n is zero, malloc returns a minumum-sized chunk. (The minimum
    size is 16 bytes on most 32bit systems, and 24 or 32 bytes on 64bit
    systems.)  On most systems, size_t is an unsigned type, so calls
    with negative arguments are interpreted as requests for huge amounts
    of space, which will often fail. The maximum supported value of n
    differs across systems, but is in all cases less than the maximum
    representable value of a size_t.
  */
  #if __STD_C
  Void_t*  public_mALLOc(size_t);
  #else
  Void_t*  public_mALLOc();
  #endif
  
  /*
    free(Void_t* p)
    Releases the chunk of memory pointed to by p, that had been previously
    allocated using malloc or a related routine such as realloc.
    It has no effect if p is null. It can have arbitrary (i.e., bad!)
    effects if p has already been freed.
  
    Unless disabled (using mallopt), freeing very large spaces will
    when possible, automatically trigger operations that give
    back unused memory to the system, thus reducing program footprint.
  */
  #if __STD_C
  void     public_fREe(Void_t*);
  #else
  void     public_fREe();
  #endif
  
  /*
    calloc(size_t n_elements, size_t element_size);
    Returns a pointer to n_elements * element_size bytes, with all locations
    set to zero.
  */
  #if __STD_C
  Void_t*  public_cALLOc(size_t, size_t);
  #else
  Void_t*  public_cALLOc();
  #endif
  
  /*
    realloc(Void_t* p, size_t n)
    Returns a pointer to a chunk of size n that contains the same data
    as does chunk p up to the minimum of (n, p's size) bytes, or null
    if no space is available. 
  
    The returned pointer may or may not be the same as p. The algorithm
    prefers extending p when possible, otherwise it employs the
    equivalent of a malloc-copy-free sequence.
  
    If p is null, realloc is equivalent to malloc.  
  
    If space is not available, realloc returns null, errno is set (if on
    ANSI) and p is NOT freed.
  
    if n is for fewer bytes than already held by p, the newly unused
    space is lopped off and freed if possible.  Unless the #define
    REALLOC_ZERO_BYTES_FREES is set, realloc with a size argument of
    zero (re)allocates a minimum-sized chunk.
  
    Large chunks that were internally obtained via mmap will always
    be reallocated using malloc-copy-free sequences unless
    the system supports MREMAP (currently only linux).
  
    The old unix realloc convention of allowing the last-free'd chunk
    to be used as an argument to realloc is not supported.
  */
  #if __STD_C
  Void_t*  public_rEALLOc(Void_t*, size_t);
  #else
  Void_t*  public_rEALLOc();
  #endif
  
  /*
    memalign(size_t alignment, size_t n);
    Returns a pointer to a newly allocated chunk of n bytes, aligned
    in accord with the alignment argument.
  
    The alignment argument should be a power of two. If the argument is
    not a power of two, the nearest greater power is used.
    8-byte alignment is guaranteed by normal malloc calls, so don't
    bother calling memalign with an argument of 8 or less.
  
    Overreliance on memalign is a sure way to fragment space.
  */
  #if __STD_C
  Void_t*  public_mEMALIGn(size_t, size_t);
  #else
  Void_t*  public_mEMALIGn();
  #endif
  
  /*
    valloc(size_t n);
    Equivalent to memalign(pagesize, n), where pagesize is the page
    size of the system. If the pagesize is unknown, 4096 is used.
  */
  #if __STD_C
  Void_t*  public_vALLOc(size_t);
  #else
  Void_t*  public_vALLOc();
  #endif
  
  
  
  /*
    mallopt(int parameter_number, int parameter_value)
    Sets tunable parameters The format is to provide a
    (parameter-number, parameter-value) pair.  mallopt then sets the
    corresponding parameter to the argument value if it can (i.e., so
    long as the value is meaningful), and returns 1 if successful else
    0.  SVID/XPG/ANSI defines four standard param numbers for mallopt,
    normally defined in malloc.h.  Only one of these (M_MXFAST) is used
    in this malloc. The others (M_NLBLKS, M_GRAIN, M_KEEP) don't apply,
    so setting them has no effect. But this malloc also supports four
    other options in mallopt. See below for details.  Briefly, supported
    parameters are as follows (listed defaults are for "typical"
    configurations).
  
    Symbol            param #   default    allowed param values
    M_MXFAST          1         64         0-80  (0 disables fastbins)
    M_TRIM_THRESHOLD -1         128*1024   any   (-1U disables trimming)
    M_TOP_PAD        -2         0          any  
    M_MMAP_THRESHOLD -3         128*1024   any   (or 0 if no MMAP support)
    M_MMAP_MAX       -4         65536      any   (0 disables use of mmap)
  */
  #if __STD_C
  int      public_mALLOPt(int, int);
  #else
  int      public_mALLOPt();
  #endif
  
  
  /*
    mallinfo()
    Returns (by copy) a struct containing various summary statistics:
  
    arena:     current total non-mmapped bytes allocated from system 
    ordblks:   the number of free chunks 
    smblks:    the number of fastbin blocks (i.e., small chunks that
                 have been freed but not use resused or consolidated)
    hblks:     current number of mmapped regions 
    hblkhd:    total bytes held in mmapped regions 
    usmblks:   the maximum total allocated space. This will be greater
                  than current total if trimming has occurred.
    fsmblks:   total bytes held in fastbin blocks 
    uordblks:  current total allocated space (normal or mmapped)
    fordblks:  total free space 
    keepcost:  the maximum number of bytes that could ideally be released
                 back to system via malloc_trim. ("ideally" means that
                 it ignores page restrictions etc.)
  
    Because these fields are ints, but internal bookkeeping may
    be kept as longs, the reported values may wrap around zero and 
    thus be inaccurate.
  */
  #if __STD_C
  struct mallinfo public_mALLINFo(void);
  #else
  struct mallinfo public_mALLINFo();
  #endif
  
  /*
    independent_calloc(size_t n_elements, size_t element_size, Void_t* chunks[]);
  
    independent_calloc is similar to calloc, but instead of returning a
    single cleared space, it returns an array of pointers to n_elements
    independent elements that can hold contents of size elem_size, each
    of which starts out cleared, and can be independently freed,
    realloc'ed etc. The elements are guaranteed to be adjacently
    allocated (this is not guaranteed to occur with multiple callocs or
    mallocs), which may also improve cache locality in some
    applications.
  
    The "chunks" argument is optional (i.e., may be null, which is
    probably the most typical usage). If it is null, the returned array
    is itself dynamically allocated and should also be freed when it is
    no longer needed. Otherwise, the chunks array must be of at least
    n_elements in length. It is filled in with the pointers to the
    chunks.
  
    In either case, independent_calloc returns this pointer array, or
    null if the allocation failed.  If n_elements is zero and "chunks"
    is null, it returns a chunk representing an array with zero elements
    (which should be freed if not wanted).
  
    Each element must be individually freed when it is no longer
    needed. If you'd like to instead be able to free all at once, you
    should instead use regular calloc and assign pointers into this
    space to represent elements.  (In this case though, you cannot
    independently free elements.)
    
    independent_calloc simplifies and speeds up implementations of many
    kinds of pools.  It may also be useful when constructing large data
    structures that initially have a fixed number of fixed-sized nodes,
    but the number is not known at compile time, and some of the nodes
    may later need to be freed. For example:
  
    struct Node { int item; struct Node* next; };
    
    struct Node* build_list() {
      struct Node** pool;
      int n = read_number_of_nodes_needed();
      if (n <= 0) return 0;
      pool = (struct Node**)(independent_calloc(n, sizeof(struct Node), 0);
      if (pool == 0) die(); 
      // organize into a linked list... 
      struct Node* first = pool[0];
      for (i = 0; i < n-1; ++i) 
        pool[i]->next = pool[i+1];
      free(pool);     // Can now free the array (or not, if it is needed later)
      return first;
    }
  */
  #if __STD_C
  Void_t** public_iCALLOc(size_t, size_t, Void_t**);
  #else
  Void_t** public_iCALLOc();
  #endif
  
  /*
    independent_comalloc(size_t n_elements, size_t sizes[], Void_t* chunks[]);
  
    independent_comalloc allocates, all at once, a set of n_elements
    chunks with sizes indicated in the "sizes" array.    It returns
    an array of pointers to these elements, each of which can be
    independently freed, realloc'ed etc. The elements are guaranteed to
    be adjacently allocated (this is not guaranteed to occur with
    multiple callocs or mallocs), which may also improve cache locality
    in some applications.
  
    The "chunks" argument is optional (i.e., may be null). If it is null
    the returned array is itself dynamically allocated and should also
    be freed when it is no longer needed. Otherwise, the chunks array
    must be of at least n_elements in length. It is filled in with the
    pointers to the chunks.
  
    In either case, independent_comalloc returns this pointer array, or
    null if the allocation failed.  If n_elements is zero and chunks is
    null, it returns a chunk representing an array with zero elements
    (which should be freed if not wanted).
    
    Each element must be individually freed when it is no longer
    needed. If you'd like to instead be able to free all at once, you
    should instead use a single regular malloc, and assign pointers at
    particular offsets in the aggregate space. (In this case though, you 
    cannot independently free elements.)
  
    independent_comallac differs from independent_calloc in that each
    element may have a different size, and also that it does not
    automatically clear elements.
  
    independent_comalloc can be used to speed up allocation in cases
    where several structs or objects must always be allocated at the
    same time.  For example:
  
    struct Head { ... }
    struct Foot { ... }
  
    void send_message(char* msg) {
      int msglen = strlen(msg);
      size_t sizes[3] = { sizeof(struct Head), msglen, sizeof(struct Foot) };
      void* chunks[3];
      if (independent_comalloc(3, sizes, chunks) == 0)
        die();
      struct Head* head = (struct Head*)(chunks[0]);
      char*        body = (char*)(chunks[1]);
      struct Foot* foot = (struct Foot*)(chunks[2]);
      // ...
    }
  
    In general though, independent_comalloc is worth using only for
    larger values of n_elements. For small values, you probably won't
    detect enough difference from series of malloc calls to bother.
  
    Overuse of independent_comalloc can increase overall memory usage,
    since it cannot reuse existing noncontiguous small chunks that
    might be available for some of the elements.
  */
  #if __STD_C
  Void_t** public_iCOMALLOc(size_t, size_t*, Void_t**);
  #else
  Void_t** public_iCOMALLOc();
  #endif
  
  
  /*
    pvalloc(size_t n);
    Equivalent to valloc(minimum-page-that-holds(n)), that is,
    round up n to nearest pagesize.
   */
  #if __STD_C
  Void_t*  public_pVALLOc(size_t);
  #else
  Void_t*  public_pVALLOc();
  #endif
  
  /*
    cfree(Void_t* p);
    Equivalent to free(p).
  
    cfree is needed/defined on some systems that pair it with calloc,
    for odd historical reasons (such as: cfree is used in example 
    code in the first edition of K&R).
  */
  #if __STD_C
  void     public_cFREe(Void_t*);
  #else
  void     public_cFREe();
  #endif
  
  /*
    malloc_trim(size_t pad);
  
    If possible, gives memory back to the system (via negative
    arguments to sbrk) if there is unused memory at the `high' end of
    the malloc pool. You can call this after freeing large blocks of
    memory to potentially reduce the system-level memory requirements
    of a program. However, it cannot guarantee to reduce memory. Under
    some allocation patterns, some large free blocks of memory will be
    locked between two used chunks, so they cannot be given back to
    the system.
    
    The `pad' argument to malloc_trim represents the amount of free
    trailing space to leave untrimmed. If this argument is zero,
    only the minimum amount of memory to maintain internal data
    structures will be left (one page or less). Non-zero arguments
    can be supplied to maintain enough trailing space to service
    future expected allocations without having to re-obtain memory
    from the system.
    
    Malloc_trim returns 1 if it actually released any memory, else 0.
    On systems that do not support "negative sbrks", it will always
    rreturn 0.
  */
  #if __STD_C
  int      public_mTRIm(size_t);
  #else
  int      public_mTRIm();
  #endif
  
  /*
    malloc_usable_size(Void_t* p);
  
    Returns the number of bytes you can actually use in
    an allocated chunk, which may be more than you requested (although
    often not) due to alignment and minimum size constraints.
    You can use this many bytes without worrying about
    overwriting other allocated objects. This is not a particularly great
    programming practice. malloc_usable_size can be more useful in
    debugging and assertions, for example:
  
    p = malloc(n);
    assert(malloc_usable_size(p) >= 256);
  
  */
  #if __STD_C
  size_t   public_mUSABLe(Void_t*);
  #else
  size_t   public_mUSABLe();
  #endif
  
  /*
    malloc_stats();
    Prints on stderr the amount of space obtained from the system (both
    via sbrk and mmap), the maximum amount (which may be more than
    current if malloc_trim and/or munmap got called), and the current
    number of bytes allocated via malloc (or realloc, etc) but not yet
    freed. Note that this is the number of bytes allocated, not the
    number requested. It will be larger than the number requested
    because of alignment and bookkeeping overhead. Because it includes
    alignment wastage as being in use, this figure may be greater than
    zero even when no user-level chunks are allocated.
  
    The reported current and maximum system memory can be inaccurate if
    a program makes other calls to system memory allocation functions
    (normally sbrk) outside of malloc.
  
    malloc_stats prints only the most commonly interesting statistics.
    More information can be obtained by calling mallinfo.
  
  */
  #if __STD_C
  void     public_mSTATs();
  #else
  void     public_mSTATs();
  #endif
  
  /* mallopt tuning options */
  
  /*
    M_MXFAST is the maximum request size used for "fastbins", special bins
    that hold returned chunks without consolidating their spaces. This
    enables future requests for chunks of the same size to be handled
    very quickly, but can increase fragmentation, and thus increase the
    overall memory footprint of a program.
  
    This malloc manages fastbins very conservatively yet still
    efficiently, so fragmentation is rarely a problem for values less
    than or equal to the default.  The maximum supported value of MXFAST
    is 80. You wouldn't want it any higher than this anyway.  Fastbins
    are designed especially for use with many small structs, objects or
    strings -- the default handles structs/objects/arrays with sizes up
    to 8 4byte fields, or small strings representing words, tokens,
    etc. Using fastbins for larger objects normally worsens
    fragmentation without improving speed.
  
    M_MXFAST is set in REQUEST size units. It is internally used in
    chunksize units, which adds padding and alignment.  You can reduce
    M_MXFAST to 0 to disable all use of fastbins.  This causes the malloc
    algorithm to be a closer approximation of fifo-best-fit in all cases,
    not just for larger requests, but will generally cause it to be
    slower.
  */
  
  
  /* M_MXFAST is a standard SVID/XPG tuning option, usually listed in malloc.h */
  #ifndef M_MXFAST
  #define M_MXFAST            1    
  #endif
  
  #ifndef DEFAULT_MXFAST
  #define DEFAULT_MXFAST     64
  #endif
  
  
  /*
    M_TRIM_THRESHOLD is the maximum amount of unused top-most memory
    to keep before releasing via malloc_trim in free().
  
    Automatic trimming is mainly useful in long-lived programs.
    Because trimming via sbrk can be slow on some systems, and can
    sometimes be wasteful (in cases where programs immediately
    afterward allocate more large chunks) the value should be high
    enough so that your overall system performance would improve by
    releasing this much memory.
  
    The trim threshold and the mmap control parameters (see below)
    can be traded off with one another. Trimming and mmapping are
    two different ways of releasing unused memory back to the
    system. Between these two, it is often possible to keep
    system-level demands of a long-lived program down to a bare
    minimum. For example, in one test suite of sessions measuring
    the XF86 X server on Linux, using a trim threshold of 128K and a
    mmap threshold of 192K led to near-minimal long term resource
    consumption.
  
    If you are using this malloc in a long-lived program, it should
    pay to experiment with these values.  As a rough guide, you
    might set to a value close to the average size of a process
    (program) running on your system.  Releasing this much memory
    would allow such a process to run in memory.  Generally, it's
    worth it to tune for trimming rather tham memory mapping when a
    program undergoes phases where several large chunks are
    allocated and released in ways that can reuse each other's
    storage, perhaps mixed with phases where there are no such
    chunks at all.  And in well-behaved long-lived programs,
    controlling release of large blocks via trimming versus mapping
    is usually faster.
  
    However, in most programs, these parameters serve mainly as
    protection against the system-level effects of carrying around
    massive amounts of unneeded memory. Since frequent calls to
    sbrk, mmap, and munmap otherwise degrade performance, the default
    parameters are set to relatively high values that serve only as
    safeguards.
  
    The trim value It must be greater than page size to have any useful
    effect.  To disable trimming completely, you can set to 
    (unsigned long)(-1)
  
    Trim settings interact with fastbin (MXFAST) settings: Unless
    TRIM_FASTBINS is defined, automatic trimming never takes place upon
    freeing a chunk with size less than or equal to MXFAST. Trimming is
    instead delayed until subsequent freeing of larger chunks. However,
    you can still force an attempted trim by calling malloc_trim.
  
    Also, trimming is not generally possible in cases where
    the main arena is obtained via mmap.
  
    Note that the trick some people use of mallocing a huge space and
    then freeing it at program startup, in an attempt to reserve system
    memory, doesn't have the intended effect under automatic trimming,
    since that memory will immediately be returned to the system.
  */
  
  #define M_TRIM_THRESHOLD       -1
  
  #ifndef DEFAULT_TRIM_THRESHOLD
  #define DEFAULT_TRIM_THRESHOLD (128 * 1024)
  #endif
  
  /*
    M_TOP_PAD is the amount of extra `padding' space to allocate or
    retain whenever sbrk is called. It is used in two ways internally:
  
    * When sbrk is called to extend the top of the arena to satisfy
    a new malloc request, this much padding is added to the sbrk
    request.
  
    * When malloc_trim is called automatically from free(),
    it is used as the `pad' argument.
  
    In both cases, the actual amount of padding is rounded
    so that the end of the arena is always a system page boundary.
  
    The main reason for using padding is to avoid calling sbrk so
    often. Having even a small pad greatly reduces the likelihood
    that nearly every malloc request during program start-up (or
    after trimming) will invoke sbrk, which needlessly wastes
    time.
  
    Automatic rounding-up to page-size units is normally sufficient
    to avoid measurable overhead, so the default is 0.  However, in
    systems where sbrk is relatively slow, it can pay to increase
    this value, at the expense of carrying around more memory than
    the program needs.
  */
  
  #define M_TOP_PAD              -2
  
  #ifndef DEFAULT_TOP_PAD
  #define DEFAULT_TOP_PAD        (0)
  #endif
  
  /*
    M_MMAP_THRESHOLD is the request size threshold for using mmap()
    to service a request. Requests of at least this size that cannot
    be allocated using already-existing space will be serviced via mmap.
    (If enough normal freed space already exists it is used instead.)
  
    Using mmap segregates relatively large chunks of memory so that
    they can be individually obtained and released from the host
    system. A request serviced through mmap is never reused by any
    other request (at least not directly; the system may just so
    happen to remap successive requests to the same locations).
  
    Segregating space in this way has the benefits that:
  
     1. Mmapped space can ALWAYS be individually released back 
        to the system, which helps keep the system level memory 
        demands of a long-lived program low. 
     2. Mapped memory can never become `locked' between
        other chunks, as can happen with normally allocated chunks, which
        means that even trimming via malloc_trim would not release them.
     3. On some systems with "holes" in address spaces, mmap can obtain
        memory that sbrk cannot.
  
    However, it has the disadvantages that:
  
     1. The space cannot be reclaimed, consolidated, and then
        used to service later requests, as happens with normal chunks.
     2. It can lead to more wastage because of mmap page alignment
        requirements
     3. It causes malloc performance to be more dependent on host
        system memory management support routines which may vary in
        implementation quality and may impose arbitrary
        limitations. Generally, servicing a request via normal
        malloc steps is faster than going through a system's mmap.
  
    The advantages of mmap nearly always outweigh disadvantages for
    "large" chunks, but the value of "large" varies across systems.  The
    default is an empirically derived value that works well in most
    systems.
  */
  
  #define M_MMAP_THRESHOLD      -3
  
  #ifndef DEFAULT_MMAP_THRESHOLD
  #define DEFAULT_MMAP_THRESHOLD (128 * 1024)
  #endif
  
  /*
    M_MMAP_MAX is the maximum number of requests to simultaneously
    service using mmap. This parameter exists because
  . Some systems have a limited number of internal tables for
    use by mmap, and using more than a few of them may degrade
    performance.
  
    The default is set to a value that serves only as a safeguard.
    Setting to 0 disables use of mmap for servicing large requests.  If
    HAVE_MMAP is not set, the default value is 0, and attempts to set it
    to non-zero values in mallopt will fail.
  */
  
  #define M_MMAP_MAX             -4
  
  #ifndef DEFAULT_MMAP_MAX
  #if HAVE_MMAP
  #define DEFAULT_MMAP_MAX       (65536)
  #else
  #define DEFAULT_MMAP_MAX       (0)
  #endif
  #endif
  
  #ifdef __cplusplus
  };  /* end of extern "C" */
  #endif
  
  /* 
    ========================================================================
    To make a fully customizable malloc.h header file, cut everything
    above this line, put into file malloc.h, edit to suit, and #include it 
    on the next line, as well as in programs that use this malloc.
    ========================================================================
  */
  
  /* #include "malloc.h" */
  
  /* --------------------- public wrappers ---------------------- */
  
  #ifdef USE_PUBLIC_MALLOC_WRAPPERS
  
  /* Declare all routines as internal */
  #if __STD_C
  static Void_t*  mALLOc(size_t);
  static void     fREe(Void_t*);
  static Void_t*  rEALLOc(Void_t*, size_t);
  static Void_t*  mEMALIGn(size_t, size_t);
  static Void_t*  vALLOc(size_t);
  static Void_t*  pVALLOc(size_t);
  static Void_t*  cALLOc(size_t, size_t);
  static Void_t** iCALLOc(size_t, size_t, Void_t**);
  static Void_t** iCOMALLOc(size_t, size_t*, Void_t**);
  static void     cFREe(Void_t*);
  static int      mTRIm(size_t);
  static size_t   mUSABLe(Void_t*);
  static void     mSTATs();
  static int      mALLOPt(int, int);
  static struct mallinfo mALLINFo(void);
  #else
  static Void_t*  mALLOc();
  static void     fREe();
  static Void_t*  rEALLOc();
  static Void_t*  mEMALIGn();
  static Void_t*  vALLOc();
  static Void_t*  pVALLOc();
  static Void_t*  cALLOc();
  static Void_t** iCALLOc();
  static Void_t** iCOMALLOc();
  static void     cFREe();
  static int      mTRIm();
  static size_t   mUSABLe();
  static void     mSTATs();
  static int      mALLOPt();
  static struct mallinfo mALLINFo();
  #endif
  
  /*
    MALLOC_PREACTION and MALLOC_POSTACTION should be
    defined to return 0 on success, and nonzero on failure.
    The return value of MALLOC_POSTACTION is currently ignored
    in wrapper functions since there is no reasonable default
    action to take on failure.
  */
  
  
  #ifdef USE_MALLOC_LOCK
  
  #ifdef WIN32
  
  static int mALLOC_MUTEx;
  #define MALLOC_PREACTION   slwait(&mALLOC_MUTEx)
  #define MALLOC_POSTACTION  slrelease(&mALLOC_MUTEx)
  
  #else
  
  #include <pthread.h>
  
  static pthread_mutex_t mALLOC_MUTEx = PTHREAD_MUTEX_INITIALIZER;
  
  #define MALLOC_PREACTION   pthread_mutex_lock(&mALLOC_MUTEx)
  #define MALLOC_POSTACTION  pthread_mutex_unlock(&mALLOC_MUTEx)
  
  #endif /* USE_MALLOC_LOCK */
  
  #else
  
  /* Substitute anything you like for these */
  
  #define MALLOC_PREACTION   (0)
  #define MALLOC_POSTACTION  (0)
  
  #endif
  
  Void_t* public_mALLOc(size_t bytes) {
    Void_t* m;
    if (MALLOC_PREACTION != 0) {
      return 0;
    }
    m = mALLOc(bytes);
    if (MALLOC_POSTACTION != 0) {
    }
    return m;
  }
  
  void public_fREe(Void_t* m) {
    if (MALLOC_PREACTION != 0) {
      return;
    }
    fREe(m);
    if (MALLOC_POSTACTION != 0) {
    }
  }
  
  Void_t* public_rEALLOc(Void_t* m, size_t bytes) {
    if (MALLOC_PREACTION != 0) {
      return 0;
    }
    m = rEALLOc(m, bytes);
    if (MALLOC_POSTACTION != 0) {
    }
    return m;
  }
  
  Void_t* public_mEMALIGn(size_t alignment, size_t bytes) {
    Void_t* m;
    if (MALLOC_PREACTION != 0) {
      return 0;
    }
    m = mEMALIGn(alignment, bytes);
    if (MALLOC_POSTACTION != 0) {
    }
    return m;
  }
  
  Void_t* public_vALLOc(size_t bytes) {
    Void_t* m;
    if (MALLOC_PREACTION != 0) {
      return 0;
    }
    m = vALLOc(bytes);
    if (MALLOC_POSTACTION != 0) {
    }
    return m;
  }
  
  Void_t* public_pVALLOc(size_t bytes) {
    Void_t* m;
    if (MALLOC_PREACTION != 0) {
      return 0;
    }
    m = pVALLOc(bytes);
    if (MALLOC_POSTACTION != 0) {
    }
    return m;
  }
  
  Void_t* public_cALLOc(size_t n, size_t elem_size) {
    Void_t* m;
    if (MALLOC_PREACTION != 0) {
      return 0;
    }
    m = cALLOc(n, elem_size);
    if (MALLOC_POSTACTION != 0) {
    }
    return m;
  }
  
  
  Void_t** public_iCALLOc(size_t n, size_t elem_size, Void_t** chunks) {
    Void_t** m;
    if (MALLOC_PREACTION != 0) {
      return 0;
    }
    m = iCALLOc(n, elem_size, chunks);
    if (MALLOC_POSTACTION != 0) {
    }
    return m;
  }
  
  Void_t** public_iCOMALLOc(size_t n, size_t sizes[], Void_t** chunks) {
    Void_t** m;
    if (MALLOC_PREACTION != 0) {
      return 0;
    }
    m = iCOMALLOc(n, sizes, chunks);
    if (MALLOC_POSTACTION != 0) {
    }
    return m;
  }
  
  void public_cFREe(Void_t* m) {
    if (MALLOC_PREACTION != 0) {
      return;
    }
    cFREe(m);
    if (MALLOC_POSTACTION != 0) {
    }
  }
  
  int public_mTRIm(size_t s) {
    int result;
    if (MALLOC_PREACTION != 0) {
      return 0;
    }
    result = mTRIm(s);
    if (MALLOC_POSTACTION != 0) {
    }
    return result;
  }
  
  size_t public_mUSABLe(Void_t* m) {
    size_t result;
    if (MALLOC_PREACTION != 0) {
      return 0;
    }
    result = mUSABLe(m);
    if (MALLOC_POSTACTION != 0) {
    }
    return result;
  }
  
  void public_mSTATs() {
    if (MALLOC_PREACTION != 0) {
      return;
    }
    mSTATs();
    if (MALLOC_POSTACTION != 0) {
    }
  }
  
  struct mallinfo public_mALLINFo() {
    struct mallinfo m;
    if (MALLOC_PREACTION != 0) {
      struct mallinfo nm = { 0, 0, 0, 0, 0, 0, 0, 0, 0, 0 };
      return nm;
    }
    m = mALLINFo();
    if (MALLOC_POSTACTION != 0) {
    }
    return m;
  }
  
  int public_mALLOPt(int p, int v) {
    int result;
    if (MALLOC_PREACTION != 0) {
      return 0;
    }
    result = mALLOPt(p, v);
    if (MALLOC_POSTACTION != 0) {
    }
    return result;
  }
  
  #endif
  
  
  
  /* ------------- Optional versions of memcopy ---------------- */
  
  
  #if USE_MEMCPY
  
  /* 
    Note: memcpy is ONLY invoked with non-overlapping regions,
    so the (usually slower) memmove is not needed.
  */
  
  #define MALLOC_COPY(dest, src, nbytes)  memcpy(dest, src, nbytes)
  #define MALLOC_ZERO(dest, nbytes)       memset(dest, 0,   nbytes)
  
  #else /* !USE_MEMCPY */
  
  /* Use Duff's device for good zeroing/copying performance. */
  
  #define MALLOC_ZERO(charp, nbytes)                                            \
  do {                                                                          \
    INTERNAL_SIZE_T* mzp = (INTERNAL_SIZE_T*)(charp);                           \
    unsigned long mctmp = (nbytes)/sizeof(INTERNAL_SIZE_T);                     \
    long mcn;                                                                   \
    if (mctmp < 8) mcn = 0; else { mcn = (mctmp-1)/8; mctmp %= 8; }             \
    switch (mctmp) {                                                            \
      case 0: for(;;) { *mzp++ = 0;                                             \
      case 7:           *mzp++ = 0;                                             \
      case 6:           *mzp++ = 0;                                             \
      case 5:           *mzp++ = 0;                                             \
      case 4:           *mzp++ = 0;                                             \
      case 3:           *mzp++ = 0;                                             \
      case 2:           *mzp++ = 0;                                             \
      case 1:           *mzp++ = 0; if(mcn <= 0) break; mcn--; }                \
    }                                                                           \
  } while(0)
  
  define MALLOC_COPY(dest,src,nbytes)                                           \
  do {                                                                          \
    INTERNAL_SIZE_T* mcsrc = (INTERNAL_SIZE_T*) src;                            \
    INTERNAL_SIZE_T* mcdst = (INTERNAL_SIZE_T*) dest;                           \
    unsigned long mctmp = (nbytes)/sizeof(INTERNAL_SIZE_T);                     \
    long mcn;                                                                   \
    if (mctmp < 8) mcn = 0; else { mcn = (mctmp-1)/8; mctmp %= 8; }             \
    switch (mctmp) {                                                            \
      case 0: for(;;) { *mcdst++ = *mcsrc++;                                    \
      case 7:           *mcdst++ = *mcsrc++;                                    \
      case 6:           *mcdst++ = *mcsrc++;                                    \
      case 5:           *mcdst++ = *mcsrc++;                                    \
      case 4:           *mcdst++ = *mcsrc++;                                    \
      case 3:           *mcdst++ = *mcsrc++;                                    \
      case 2:           *mcdst++ = *mcsrc++;                                    \
      case 1:           *mcdst++ = *mcsrc++; if(mcn <= 0) break; mcn--; }       \
    }                                                                           \
  } while(0)
  
  #endif
  
  /* ------------------ MMAP support ------------------  */
  
  
  #if HAVE_MMAP
  
  #include <fcntl.h>
  #ifndef LACKS_SYS_MMAN_H
  #include <sys/mman.h>
  #endif
  
  #if !defined(MAP_ANONYMOUS) && defined(MAP_ANON)
  #define MAP_ANONYMOUS MAP_ANON
  #endif
  
  /* 
     Nearly all versions of mmap support MAP_ANONYMOUS, 
     so the following is unlikely to be needed, but is
     supplied just in case.
  */
  
  #ifndef MAP_ANONYMOUS
  
  static int dev_zero_fd = -1; /* Cached file descriptor for /dev/zero. */
  
  #define MMAP(addr, size, prot, flags) ((dev_zero_fd < 0) ? \
   (dev_zero_fd = open("/dev/zero", O_RDWR), \
    mmap((addr), (size), (prot), (flags), dev_zero_fd, 0)) : \
     mmap((addr), (size), (prot), (flags), dev_zero_fd, 0))
  
  #else
  
  #define MMAP(addr, size, prot, flags) \
   (mmap((addr), (size), (prot), (flags)|MAP_ANONYMOUS, -1, 0))
  
  #endif
  
  
  #endif /* HAVE_MMAP */
  
  
  /*
    -----------------------  Chunk representations -----------------------
  */
  
  
  /*
    This struct declaration is misleading (but accurate and necessary).
    It declares a "view" into memory allowing access to necessary
    fields at known offsets from a given base. See explanation below.
  */
  
  struct malloc_chunk {
  
    INTERNAL_SIZE_T      prev_size;  /* Size of previous chunk (if free).  */
    INTERNAL_SIZE_T      size;       /* Size in bytes, including overhead. */
  
    struct malloc_chunk* fd;         /* double links -- used only if free. */
    struct malloc_chunk* bk;
  };
  
  
  typedef struct malloc_chunk* mchunkptr;
  
  /*
     malloc_chunk details:
  
      (The following includes lightly edited explanations by Colin Plumb.)
  
      Chunks of memory are maintained using a `boundary tag' method as
      described in e.g., Knuth or Standish.  (See the paper by Paul
      Wilson ftp://ftp.cs.utexas.edu/pub/garbage/allocsrv.ps for a
      survey of such techniques.)  Sizes of free chunks are stored both
      in the front of each chunk and at the end.  This makes
      consolidating fragmented chunks into bigger chunks very fast.  The
      size fields also hold bits representing whether chunks are free or
      in use.
  
      An allocated chunk looks like this:
  
  
      chunk-> +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
              |             Size of previous chunk, if allocated            | |
              +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
              |             Size of chunk, in bytes                         |P|
        mem-> +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
              |             User data starts here...                          .
              .                                                               .
              .             (malloc_usable_space() bytes)                     .
              .                                                               |
  nextchunk-> +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
              |             Size of chunk                                     |
              +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
  
  
      Where "chunk" is the front of the chunk for the purpose of most of
      the malloc code, but "mem" is the pointer that is returned to the
      user.  "Nextchunk" is the beginning of the next contiguous chunk.
  
      Chunks always begin on even word boundries, so the mem portion
      (which is returned to the user) is also on an even word boundary, and
      thus at least double-word aligned.
  
      Free chunks are stored in circular doubly-linked lists, and look like this:
  
      chunk-> +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
              |             Size of previous chunk                            |
              +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      `head:' |             Size of chunk, in bytes                         |P|
        mem-> +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
              |             Forward pointer to next chunk in list             |
              +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
              |             Back pointer to previous chunk in list            |
              +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
              |             Unused space (may be 0 bytes long)                .
              .                                                               .
              .                                                               |
  nextchunk-> +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      `foot:' |             Size of chunk, in bytes                           |
              +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
  
      The P (PREV_INUSE) bit, stored in the unused low-order bit of the
      chunk size (which is always a multiple of two words), is an in-use
      bit for the *previous* chunk.  If that bit is *clear*, then the
      word before the current chunk size contains the previous chunk
      size, and can be used to find the front of the previous chunk.
      The very first chunk allocated always has this bit set,
      preventing access to non-existent (or non-owned) memory. If
      prev_inuse is set for any given chunk, then you CANNOT determine
      the size of the previous chunk, and might even get a memory
      addressing fault when trying to do so.
  
      Note that the `foot' of the current chunk is actually represented
      as the prev_size of the NEXT chunk. This makes it easier to
      deal with alignments etc but can be very confusing when trying
      to extend or adapt this code.
  
      The two exceptions to all this are
  
       1. The special chunk `top' doesn't bother using the
          trailing size field since there is no next contiguous chunk
          that would have to index off it. After initialization, `top'
          is forced to always exist.  If it would become less than
          MINSIZE bytes long, it is replenished.
  
       2. Chunks allocated via mmap, which have the second-lowest-order
          bit (IS_MMAPPED) set in their size fields.  Because they are
          allocated one-by-one, each must contain its own trailing size field.
  
  */
  
  /*
    ---------- Size and alignment checks and conversions ----------
  */
  
  /* conversion from malloc headers to user pointers, and back */
  
  #define chunk2mem(p)   ((Void_t*)((char*)(p) + 2*SIZE_SZ))
  #define mem2chunk(mem) ((mchunkptr)((char*)(mem) - 2*SIZE_SZ))
  
  /* The smallest possible chunk */
  #define MIN_CHUNK_SIZE        (sizeof(struct malloc_chunk))
  
  /* The smallest size we can malloc is an aligned minimal chunk */
  
  #define MINSIZE  \
    (unsigned long)(((MIN_CHUNK_SIZE+MALLOC_ALIGN_MASK) & ~MALLOC_ALIGN_MASK))
  
  /* Check if m has acceptable alignment */
  
  #define aligned_OK(m)  (((unsigned long)((m)) & (MALLOC_ALIGN_MASK)) == 0)
  
  
  /* 
     Check if a request is so large that it would wrap around zero when
     padded and aligned. To simplify some other code, the bound is made
     low enough so that adding MINSIZE will also not wrap around sero.
  */
  
  #define REQUEST_OUT_OF_RANGE(req)                                 \
    ((unsigned long)(req) >=                                        \
     (unsigned long)(INTERNAL_SIZE_T)(-2 * MINSIZE))    
  
  /* pad request bytes into a usable size -- internal version */
  
  #define request2size(req)                                         \
    (((req) + SIZE_SZ + MALLOC_ALIGN_MASK < MINSIZE)  ?             \
     MINSIZE :                                                      \
     ((req) + SIZE_SZ + MALLOC_ALIGN_MASK) & ~MALLOC_ALIGN_MASK)
  
  /*  Same, except also perform argument check */
  
  #define checked_request2size(req, sz)                             \
    if (REQUEST_OUT_OF_RANGE(req)) {                                \
      MALLOC_FAILURE_ACTION;                                        \
      return 0;                                                     \
    }                                                               \
    (sz) = request2size(req);                                              
  
  /*
    --------------- Physical chunk operations ---------------
  */
  
  
  /* size field is or'ed with PREV_INUSE when previous adjacent chunk in use */
  #define PREV_INUSE 0x1
  
  /* extract inuse bit of previous chunk */
  #define prev_inuse(p)       ((p)->size & PREV_INUSE)
  
  
  /* size field is or'ed with IS_MMAPPED if the chunk was obtained with mmap() */
  #define IS_MMAPPED 0x2
  
  /* check for mmap()'ed chunk */
  #define chunk_is_mmapped(p) ((p)->size & IS_MMAPPED)
  
  /* 
    Bits to mask off when extracting size 
  
    Note: IS_MMAPPED is intentionally not masked off from size field in
    macros for which mmapped chunks should never be seen. This should
    cause helpful core dumps to occur if it is tried by accident by
    people extending or adapting this malloc.
  */
  #define SIZE_BITS (PREV_INUSE|IS_MMAPPED)
  
  /* Get size, ignoring use bits */
  #define chunksize(p)         ((p)->size & ~(SIZE_BITS))
  
  
  /* Ptr to next physical malloc_chunk. */
  #define next_chunk(p) ((mchunkptr)( ((char*)(p)) + ((p)->size & ~PREV_INUSE) ))
  
  /* Ptr to previous physical malloc_chunk */
  #define prev_chunk(p) ((mchunkptr)( ((char*)(p)) - ((p)->prev_size) ))
  
  /* Treat space at ptr + offset as a chunk */
  #define chunk_at_offset(p, s)  ((mchunkptr)(((char*)(p)) + (s)))
  
  /* extract p's inuse bit */
  #define inuse(p)\
  ((((mchunkptr)(((char*)(p))+((p)->size & ~PREV_INUSE)))->size) & PREV_INUSE)
  
  /* set/clear chunk as being inuse without otherwise disturbing */
  #define set_inuse(p)\
  ((mchunkptr)(((char*)(p)) + ((p)->size & ~PREV_INUSE)))->size |= PREV_INUSE
  
  #define clear_inuse(p)\
  ((mchunkptr)(((char*)(p)) + ((p)->size & ~PREV_INUSE)))->size &= ~(PREV_INUSE)
  
  
  /* check/set/clear inuse bits in known places */
  #define inuse_bit_at_offset(p, s)\
   (((mchunkptr)(((char*)(p)) + (s)))->size & PREV_INUSE)
  
  #define set_inuse_bit_at_offset(p, s)\
   (((mchunkptr)(((char*)(p)) + (s)))->size |= PREV_INUSE)
  
  #define clear_inuse_bit_at_offset(p, s)\
   (((mchunkptr)(((char*)(p)) + (s)))->size &= ~(PREV_INUSE))
  
  
  /* Set size at head, without disturbing its use bit */
  #define set_head_size(p, s)  ((p)->size = (((p)->size & PREV_INUSE) | (s)))
  
  /* Set size/use field */
  #define set_head(p, s)       ((p)->size = (s))
  
  /* Set size at footer (only when chunk is not in use) */
  #define set_foot(p, s)       (((mchunkptr)((char*)(p) + (s)))->prev_size = (s))
  
  
  /*
    -------------------- Internal data structures --------------------
  
     All internal state is held in an instance of malloc_state defined
     below. There are no other static variables, except in two optional
     cases: 
     * If USE_MALLOC_LOCK is defined, the mALLOC_MUTEx declared above. 
     * If HAVE_MMAP is true, but mmap doesn't support
       MAP_ANONYMOUS, a dummy file descriptor for mmap.
  
     Beware of lots of tricks that minimize the total bookkeeping space
     requirements. The result is a little over 1K bytes (for 4byte
     pointers and size_t.)
  */
  
  /*
    Bins
  
      An array of bin headers for free chunks. Each bin is doubly
      linked.  The bins are approximately proportionally (log) spaced.
      There are a lot of these bins (128). This may look excessive, but
      works very well in practice.  Most bins hold sizes that are
      unusual as malloc request sizes, but are more usual for fragments
      and consolidated sets of chunks, which is what these bins hold, so
      they can be found quickly.  All procedures maintain the invariant
      that no consolidated chunk physically borders another one, so each
      chunk in a list is known to be preceeded and followed by either
      inuse chunks or the ends of memory.
  
      Chunks in bins are kept in size order, with ties going to the
      approximately least recently used chunk. Ordering isn't needed
      for the small bins, which all contain the same-sized chunks, but
      facilitates best-fit allocation for larger chunks. These lists
      are just sequential. Keeping them in order almost never requires
      enough traversal to warrant using fancier ordered data
      structures.  
  
      Chunks of the same size are linked with the most
      recently freed at the front, and allocations are taken from the
      back.  This results in LRU (FIFO) allocation order, which tends
      to give each chunk an equal opportunity to be consolidated with
      adjacent freed chunks, resulting in larger free chunks and less
      fragmentation.
  
      To simplify use in double-linked lists, each bin header acts
      as a malloc_chunk. This avoids special-casing for headers.
      But to conserve space and improve locality, we allocate
      only the fd/bk pointers of bins, and then use repositioning tricks
      to treat these as the fields of a malloc_chunk*.  
  */
  
  typedef struct malloc_chunk* mbinptr;
  
  /* addressing -- note that bin_at(0) does not exist */
  #define bin_at(m, i) ((mbinptr)((char*)&((m)->bins[(i)<<1]) - (SIZE_SZ<<1)))
  
  /* analog of ++bin */
  #define next_bin(b)  ((mbinptr)((char*)(b) + (sizeof(mchunkptr)<<1)))
  
  /* Reminders about list directionality within bins */
  #define first(b)     ((b)->fd)
  #define last(b)      ((b)->bk)
  
  /* Take a chunk off a bin list */
  #define unlink(P, BK, FD) {                                            \
    FD = P->fd;                                                          \
    BK = P->bk;                                                          \
    FD->bk = BK;                                                         \
    BK->fd = FD;                                                         \
  }
  
  /*
    Indexing
  
      Bins for sizes < 512 bytes contain chunks of all the same size, spaced
      8 bytes apart. Larger bins are approximately logarithmically spaced:
  
      64 bins of size       8
      32 bins of size      64
      16 bins of size     512
       8 bins of size    4096
       4 bins of size   32768
       2 bins of size  262144
       1 bin  of size what's left
  
      There is actually a little bit of slop in the numbers in bin_index
      for the sake of speed. This makes no difference elsewhere.
  
      The bins top out around 1MB because we expect to service large
      requests via mmap.
  */
  
  #define NBINS             128
  #define NSMALLBINS         64
  #define SMALLBIN_WIDTH      8
  #define MIN_LARGE_SIZE    512
  
  #define in_smallbin_range(sz)  \
    ((unsigned long)(sz) < (unsigned long)MIN_LARGE_SIZE)
  
  #define smallbin_index(sz)     (((unsigned)(sz)) >> 3)
  
  #define largebin_index(sz)                                                   \
  (((((unsigned long)(sz)) >>  6) <= 32)?  56 + (((unsigned long)(sz)) >>  6): \
   ((((unsigned long)(sz)) >>  9) <= 20)?  91 + (((unsigned long)(sz)) >>  9): \
   ((((unsigned long)(sz)) >> 12) <= 10)? 110 + (((unsigned long)(sz)) >> 12): \
   ((((unsigned long)(sz)) >> 15) <=  4)? 119 + (((unsigned long)(sz)) >> 15): \
   ((((unsigned long)(sz)) >> 18) <=  2)? 124 + (((unsigned long)(sz)) >> 18): \
                                          126)
  
  #define bin_index(sz) \
   ((in_smallbin_range(sz)) ? smallbin_index(sz) : largebin_index(sz))
  
  
  /*
    Unsorted chunks
  
      All remainders from chunk splits, as well as all returned chunks,
      are first placed in the "unsorted" bin. They are then placed
      in regular bins after malloc gives them ONE chance to be used before
      binning. So, basically, the unsorted_chunks list acts as a queue,
      with chunks being placed on it in free (and malloc_consolidate),
      and taken off (to be either used or placed in bins) in malloc.
  */
  
  /* The otherwise unindexable 1-bin is used to hold unsorted chunks. */
  #define unsorted_chunks(M)          (bin_at(M, 1))
  
  /*
    Top
  
      The top-most available chunk (i.e., the one bordering the end of
      available memory) is treated specially. It is never included in
      any bin, is used only if no other chunk is available, and is
      released back to the system if it is very large (see
      M_TRIM_THRESHOLD).  Because top initially
      points to its own bin with initial zero size, thus forcing
      extension on the first malloc request, we avoid having any special
      code in malloc to check whether it even exists yet. But we still
      need to do so when getting memory from system, so we make
      initial_top treat the bin as a legal but unusable chunk during the
      interval between initialization and the first call to
      sYSMALLOc. (This is somewhat delicate, since it relies on
      the 2 preceding words to be zero during this interval as well.)
  */
  
  /* Conveniently, the unsorted bin can be used as dummy top on first call */
  #define initial_top(M)              (unsorted_chunks(M))
  
  /*
    Binmap
  
      To help compensate for the large number of bins, a one-level index
      structure is used for bin-by-bin searching.  `binmap' is a
      bitvector recording whether bins are definitely empty so they can
      be skipped over during during traversals.  The bits are NOT always
      cleared as soon as bins are empty, but instead only
      when they are noticed to be empty during traversal in malloc.
  */
  
  /* Conservatively use 32 bits per map word, even if on 64bit system */
  #define BINMAPSHIFT      5
  #define BITSPERMAP       (1U << BINMAPSHIFT)
  #define BINMAPSIZE       (NBINS / BITSPERMAP)
  
  #define idx2block(i)     ((i) >> BINMAPSHIFT)
  #define idx2bit(i)       ((1U << ((i) & ((1U << BINMAPSHIFT)-1))))
  
  #define mark_bin(m,i)    ((m)->binmap[idx2block(i)] |=  idx2bit(i))
  #define unmark_bin(m,i)  ((m)->binmap[idx2block(i)] &= ~(idx2bit(i)))
  #define get_binmap(m,i)  ((m)->binmap[idx2block(i)] &   idx2bit(i))
  
  /*
    Fastbins
  
      An array of lists holding recently freed small chunks.  Fastbins
      are not doubly linked.  It is faster to single-link them, and
      since chunks are never removed from the middles of these lists,
      double linking is not necessary. Also, unlike regular bins, they
      are not even processed in FIFO order (they use faster LIFO) since
      ordering doesn't much matter in the transient contexts in which
      fastbins are normally used.
  
      Chunks in fastbins keep their inuse bit set, so they cannot
      be consolidated with other free chunks. malloc_consolidate
      releases all chunks in fastbins and consolidates them with
      other free chunks. 
  */
  
  typedef struct malloc_chunk* mfastbinptr;
  
  /* offset 2 to use otherwise unindexable first 2 bins */
  #define fastbin_index(sz)        ((((unsigned int)(sz)) >> 3) - 2)
  
  /* The maximum fastbin request size we support */
  #define MAX_FAST_SIZE     80
  
  #define NFASTBINS  (fastbin_index(request2size(MAX_FAST_SIZE))+1)
  
  /*
    FASTBIN_CONSOLIDATION_THRESHOLD is the size of a chunk in free()
    that triggers automatic consolidation of possibly-surrounding
    fastbin chunks. This is a heuristic, so the exact value should not
    matter too much. It is defined at half the default trim threshold as a
    compromise heuristic to only attempt consolidation if it is likely
    to lead to trimming. However, it is not dynamically tunable, since
    consolidation reduces fragmentation surrounding loarge chunks even 
    if trimming is not used.
  */
  
  #define FASTBIN_CONSOLIDATION_THRESHOLD  (65536UL)
  
  /*
    Since the lowest 2 bits in max_fast don't matter in size comparisons, 
    they are used as flags.
  */
  
  /*
    FASTCHUNKS_BIT held in max_fast indicates that there are probably
    some fastbin chunks. It is set true on entering a chunk into any
    fastbin, and cleared only in malloc_consolidate.
  
    The truth value is inverted so that have_fastchunks will be true
    upon startup (since statics are zero-filled), simplifying
    initialization checks.
  */
  
  #define FASTCHUNKS_BIT        (1U)
  
  #define have_fastchunks(M)     (((M)->max_fast &  FASTCHUNKS_BIT) == 0)
  #define clear_fastchunks(M)    ((M)->max_fast |=  FASTCHUNKS_BIT)
  #define set_fastchunks(M)      ((M)->max_fast &= ~FASTCHUNKS_BIT)
  
  /*
    NONCONTIGUOUS_BIT indicates that MORECORE does not return contiguous
    regions.  Otherwise, contiguity is exploited in merging together,
    when possible, results from consecutive MORECORE calls.
  
    The initial value comes from MORECORE_CONTIGUOUS, but is
    changed dynamically if mmap is ever used as an sbrk substitute.
  */
  
  #define NONCONTIGUOUS_BIT     (2U)
  
  #define contiguous(M)          (((M)->max_fast &  NONCONTIGUOUS_BIT) == 0)
  #define noncontiguous(M)       (((M)->max_fast &  NONCONTIGUOUS_BIT) != 0)
  #define set_noncontiguous(M)   ((M)->max_fast |=  NONCONTIGUOUS_BIT)
  #define set_contiguous(M)      ((M)->max_fast &= ~NONCONTIGUOUS_BIT)
  
  /* 
     Set value of max_fast. 
     Use impossibly small value if 0.
     Precondition: there are no existing fastbin chunks.
     Setting the value clears fastchunk bit but preserves noncontiguous bit.
  */
  
  #define set_max_fast(M, s) \
    (M)->max_fast = (((s) == 0)? SMALLBIN_WIDTH: request2size(s)) | \
    FASTCHUNKS_BIT | \
    ((M)->max_fast &  NONCONTIGUOUS_BIT)
  
  
  /*
     ----------- Internal state representation and initialization -----------
  */
  
  struct malloc_state {
  
    /* The maximum chunk size to be eligible for fastbin */
    INTERNAL_SIZE_T  max_fast;   /* low 2 bits used as flags */
  
    /* Fastbins */
    mfastbinptr      fastbins[NFASTBINS];
  
    /* Base of the topmost chunk -- not otherwise kept in a bin */
    mchunkptr        top;
  
    /* The remainder from the most recent split of a small request */
    mchunkptr        last_remainder;
  
    /* Normal bins packed as described above */
    mchunkptr        bins[NBINS * 2];
  
    /* Bitmap of bins */
    unsigned int     binmap[BINMAPSIZE];
  
    /* Tunable parameters */
    unsigned long    trim_threshold;
    INTERNAL_SIZE_T  top_pad;
    INTERNAL_SIZE_T  mmap_threshold;
  
    /* Memory map support */
    int              n_mmaps;
    int              n_mmaps_max;
    int              max_n_mmaps;
  
    /* Cache malloc_getpagesize */
    unsigned int     pagesize;    
  
    /* Statistics */
    INTERNAL_SIZE_T  mmapped_mem;
    INTERNAL_SIZE_T  sbrked_mem;
    INTERNAL_SIZE_T  max_sbrked_mem;
    INTERNAL_SIZE_T  max_mmapped_mem;
    INTERNAL_SIZE_T  max_total_mem;
  };
  
  typedef struct malloc_state *mstate;
  
  /* 
     There is exactly one instance of this struct in this malloc.
     If you are adapting this malloc in a way that does NOT use a static
     malloc_state, you MUST explicitly zero-fill it before using. This
     malloc relies on the property that malloc_state is initialized to
     all zeroes (as is true of C statics).
  */
  
  static struct malloc_state av_;  /* never directly referenced */
  
  /*
     All uses of av_ are via get_malloc_state().
     At most one "call" to get_malloc_state is made per invocation of
     the public versions of malloc and free, but other routines
     that in turn invoke malloc and/or free may call more then once. 
     Also, it is called in check* routines if DEBUG is set.
  */
  
  #define get_malloc_state() (&(av_))
  
  /*
    Initialize a malloc_state struct.
  
    This is called only from within malloc_consolidate, which needs
    be called in the same contexts anyway.  It is never called directly
    outside of malloc_consolidate because some optimizing compilers try
    to inline it at all call points, which turns out not to be an
    optimization at all. (Inlining it in malloc_consolidate is fine though.)
  */
  
  #if __STD_C
  static void malloc_init_state(mstate av)
  #else
  static void malloc_init_state(av) mstate av;
  #endif
  {
    int     i;
    mbinptr bin;
    
    /* Establish circular links for normal bins */
    for (i = 1; i < NBINS; ++i) { 
      bin = bin_at(av,i);
      bin->fd = bin->bk = bin;
    }
  
    av->top_pad        = DEFAULT_TOP_PAD;
    av->n_mmaps_max    = DEFAULT_MMAP_MAX;
    av->mmap_threshold = DEFAULT_MMAP_THRESHOLD;
    av->trim_threshold = DEFAULT_TRIM_THRESHOLD;
  
  #if !MORECORE_CONTIGUOUS
    set_noncontiguous(av);
  #endif
  
    set_max_fast(av, DEFAULT_MXFAST);
  
    av->top            = initial_top(av);
    av->pagesize       = malloc_getpagesize;
  }
  
  /* 
     Other internal utilities operating on mstates
  */
  
  #if __STD_C
  static Void_t*  sYSMALLOc(INTERNAL_SIZE_T, mstate);
  static int      sYSTRIm(size_t, mstate);
  static void     malloc_consolidate(mstate);
  static Void_t** iALLOc(size_t, size_t*, int, Void_t**);
  #else
  static Void_t*  sYSMALLOc();
  static int      sYSTRIm();
  static void     malloc_consolidate();
  static Void_t** iALLOc();
  #endif
  
  /*
    Debugging support
  
    These routines make a number of assertions about the states
    of data structures that should be true at all times. If any
    are not true, it's very likely that a user program has somehow
    trashed memory. (It's also possible that there is a coding error
    in malloc. In which case, please report it!)
  */
  
  #if ! DEBUG
  
  #define check_chunk(P)
  #define check_free_chunk(P)
  #define check_inuse_chunk(P)
  #define check_remalloced_chunk(P,N)
  #define check_malloced_chunk(P,N)
  #define check_malloc_state()
  
  #else
  #define check_chunk(P)              do_check_chunk(P)
  #define check_free_chunk(P)         do_check_free_chunk(P)
  #define check_inuse_chunk(P)        do_check_inuse_chunk(P)
  #define check_remalloced_chunk(P,N) do_check_remalloced_chunk(P,N)
  #define check_malloced_chunk(P,N)   do_check_malloced_chunk(P,N)
  #define check_malloc_state()        do_check_malloc_state()
  
  /*
    Properties of all chunks
  */
  
  #if __STD_C
  static void do_check_chunk(mchunkptr p)
  #else
  static void do_check_chunk(p) mchunkptr p;
  #endif
  {
    mstate av = get_malloc_state();
    unsigned long sz = chunksize(p);
    /* min and max possible addresses assuming contiguous allocation */
    char* max_address = (char*)(av->top) + chunksize(av->top);
    char* min_address = max_address - av->sbrked_mem;
  
    if (!chunk_is_mmapped(p)) {
      
      /* Has legal address ... */
      if (p != av->top) {
        if (contiguous(av)) {
          assert(((char*)p) >= min_address);
          assert(((char*)p + sz) <= ((char*)(av->top)));
        }
      }
      else {
        /* top size is always at least MINSIZE */
        assert((unsigned long)(sz) >= MINSIZE);
        /* top predecessor always marked inuse */
        assert(prev_inuse(p));
      }
        
    }
    else {
  #if HAVE_MMAP
      /* address is outside main heap  */
      if (contiguous(av) && av->top != initial_top(av)) {
        assert(((char*)p) < min_address || ((char*)p) > max_address);
      }
      /* chunk is page-aligned */
      assert(((p->prev_size + sz) & (av->pagesize-1)) == 0);
      /* mem is aligned */
      assert(aligned_OK(chunk2mem(p)));
  #else
      /* force an appropriate assert violation if debug set */
      assert(!chunk_is_mmapped(p));
  #endif
    }
  }
  
  /*
    Properties of free chunks
  */
  
  #if __STD_C
  static void do_check_free_chunk(mchunkptr p)
  #else
  static void do_check_free_chunk(p) mchunkptr p;
  #endif
  {
    mstate av = get_malloc_state();
  
    INTERNAL_SIZE_T sz = p->size & ~PREV_INUSE;
    mchunkptr next = chunk_at_offset(p, sz);
  
    do_check_chunk(p);
  
    /* Chunk must claim to be free ... */
    assert(!inuse(p));
    assert (!chunk_is_mmapped(p));
  
    /* Unless a special marker, must have OK fields */
    if ((unsigned long)(sz) >= MINSIZE)
    {
      assert((sz & MALLOC_ALIGN_MASK) == 0);
      assert(aligned_OK(chunk2mem(p)));
      /* ... matching footer field */
      assert(next->prev_size == sz);
      /* ... and is fully consolidated */
      assert(prev_inuse(p));
      assert (next == av->top || inuse(next));
  
      /* ... and has minimally sane links */
      assert(p->fd->bk == p);
      assert(p->bk->fd == p);
    }
    else /* markers are always of size SIZE_SZ */
      assert(sz == SIZE_SZ);
  }
  
  /*
    Properties of inuse chunks
  */
  
  #if __STD_C
  static void do_check_inuse_chunk(mchunkptr p)
  #else
  static void do_check_inuse_chunk(p) mchunkptr p;
  #endif
  {
    mstate av = get_malloc_state();
    mchunkptr next;
    do_check_chunk(p);
  
    if (chunk_is_mmapped(p))
      return; /* mmapped chunks have no next/prev */
  
    /* Check whether it claims to be in use ... */
    assert(inuse(p));
  
    next = next_chunk(p);
  
    /* ... and is surrounded by OK chunks.
      Since more things can be checked with free chunks than inuse ones,
      if an inuse chunk borders them and debug is on, it's worth doing them.
    */
    if (!prev_inuse(p))  {
      /* Note that we cannot even look at prev unless it is not inuse */
      mchunkptr prv = prev_chunk(p);
      assert(next_chunk(prv) == p);
      do_check_free_chunk(prv);
    }
  
    if (next == av->top) {
      assert(prev_inuse(next));
      assert(chunksize(next) >= MINSIZE);
    }
    else if (!inuse(next))
      do_check_free_chunk(next);
  }
  
  /*
    Properties of chunks recycled from fastbins
  */
  
  #if __STD_C
  static void do_check_remalloced_chunk(mchunkptr p, INTERNAL_SIZE_T s)
  #else
  static void do_check_remalloced_chunk(p, s) mchunkptr p; INTERNAL_SIZE_T s;
  #endif
  {
    INTERNAL_SIZE_T sz = p->size & ~PREV_INUSE;
  
    do_check_inuse_chunk(p);
  
    /* Legal size ... */
    assert((sz & MALLOC_ALIGN_MASK) == 0);
    assert((unsigned long)(sz) >= MINSIZE);
    /* ... and alignment */
    assert(aligned_OK(chunk2mem(p)));
    /* chunk is less than MINSIZE more than request */
    assert((long)(sz) - (long)(s) >= 0);
    assert((long)(sz) - (long)(s + MINSIZE) < 0);
  }
  
  /*
    Properties of nonrecycled chunks at the point they are malloced
  */
  
  #if __STD_C
  static void do_check_malloced_chunk(mchunkptr p, INTERNAL_SIZE_T s)
  #else
  static void do_check_malloced_chunk(p, s) mchunkptr p; INTERNAL_SIZE_T s;
  #endif
  {
    /* same as recycled case ... */
    do_check_remalloced_chunk(p, s);
  
    /*
      ... plus,  must obey implementation invariant that prev_inuse is
      always true of any allocated chunk; i.e., that each allocated
      chunk borders either a previously allocated and still in-use
      chunk, or the base of its memory arena. This is ensured
      by making all allocations from the the `lowest' part of any found
      chunk.  This does not necessarily hold however for chunks
      recycled via fastbins.
    */
  
    assert(prev_inuse(p));
  }
  
  
  /*
    Properties of malloc_state.
  
    This may be useful for debugging malloc, as well as detecting user
    programmer errors that somehow write into malloc_state.
  
    If you are extending or experimenting with this malloc, you can
    probably figure out how to hack this routine to print out or
    display chunk addresses, sizes, bins, and other instrumentation.
  */
  
  static void do_check_malloc_state()
  {
    mstate av = get_malloc_state();
    int i;
    mchunkptr p;
    mchunkptr q;
    mbinptr b;
    unsigned int binbit;
    int empty;
    unsigned int idx;
    INTERNAL_SIZE_T size;
    unsigned long total = 0;
    int max_fast_bin;
  
    /* internal size_t must be no wider than pointer type */
    assert(sizeof(INTERNAL_SIZE_T) <= sizeof(char*));
  
    /* alignment is a power of 2 */
    assert((MALLOC_ALIGNMENT & (MALLOC_ALIGNMENT-1)) == 0);
  
    /* cannot run remaining checks until fully initialized */
    if (av->top == 0 || av->top == initial_top(av))
      return;
  
    /* pagesize is a power of 2 */
    assert((av->pagesize & (av->pagesize-1)) == 0);
  
    /* properties of fastbins */
  
    /* max_fast is in allowed range */
    assert((av->max_fast & ~1) <= request2size(MAX_FAST_SIZE));
  
    max_fast_bin = fastbin_index(av->max_fast);
  
    for (i = 0; i < NFASTBINS; ++i) {
      p = av->fastbins[i];
  
      /* all bins past max_fast are empty */
      if (i > max_fast_bin)
        assert(p == 0);
  
      while (p != 0) {
        /* each chunk claims to be inuse */
        do_check_inuse_chunk(p);
        total += chunksize(p);
        /* chunk belongs in this bin */
        assert(fastbin_index(chunksize(p)) == i);
        p = p->fd;
      }
    }
  
    if (total != 0)
      assert(have_fastchunks(av));
    else if (!have_fastchunks(av))
      assert(total == 0);
  
    /* check normal bins */
    for (i = 1; i < NBINS; ++i) {
      b = bin_at(av,i);
  
      /* binmap is accurate (except for bin 1 == unsorted_chunks) */
      if (i >= 2) {
        binbit = get_binmap(av,i);
        empty = last(b) == b;
        if (!binbit)
          assert(empty);
        else if (!empty)
          assert(binbit);
      }
  
      for (p = last(b); p != b; p = p->bk) {
        /* each chunk claims to be free */
        do_check_free_chunk(p);
        size = chunksize(p);
        total += size;
        if (i >= 2) {
          /* chunk belongs in bin */
          idx = bin_index(size);
          assert(idx == i);
          /* lists are sorted */
          assert(p->bk == b || 
                 (unsigned long)chunksize(p->bk) >= (unsigned long)chunksize(p));
        }
        /* chunk is followed by a legal chain of inuse chunks */
        for (q = next_chunk(p);
             (q != av->top && inuse(q) && 
               (unsigned long)(chunksize(q)) >= MINSIZE);
             q = next_chunk(q))
          do_check_inuse_chunk(q);
      }
    }
  
    /* top chunk is OK */
    check_chunk(av->top);
  
    /* sanity checks for statistics */
  
    assert(total <= (unsigned long)(av->max_total_mem));
    assert(av->n_mmaps >= 0);
    assert(av->n_mmaps <= av->n_mmaps_max);
    assert(av->n_mmaps <= av->max_n_mmaps);
  
    assert((unsigned long)(av->sbrked_mem) <=
           (unsigned long)(av->max_sbrked_mem));
  
    assert((unsigned long)(av->mmapped_mem) <=
           (unsigned long)(av->max_mmapped_mem));
  
    assert((unsigned long)(av->max_total_mem) >=
           (unsigned long)(av->mmapped_mem) + (unsigned long)(av->sbrked_mem));
  }
  #endif
  
  
  /* ----------- Routines dealing with system allocation -------------- */
  
  /*
    sysmalloc handles malloc cases requiring more memory from the system.
    On entry, it is assumed that av->top does not have enough
    space to service request for nb bytes, thus requiring that av->top
    be extended or replaced.
  */
  
  #if __STD_C
  static Void_t* sYSMALLOc(INTERNAL_SIZE_T nb, mstate av)
  #else
  static Void_t* sYSMALLOc(nb, av) INTERNAL_SIZE_T nb; mstate av;
  #endif
  {
    mchunkptr       old_top;        /* incoming value of av->top */
    INTERNAL_SIZE_T old_size;       /* its size */
    char*           old_end;        /* its end address */
  
    long            size;           /* arg to first MORECORE or mmap call */
    char*           brk;            /* return value from MORECORE */
  
    long            correction;     /* arg to 2nd MORECORE call */
    char*           snd_brk;        /* 2nd return val */
  
    INTERNAL_SIZE_T front_misalign; /* unusable bytes at front of new space */
    INTERNAL_SIZE_T end_misalign;   /* partial page left at end of new space */
    char*           aligned_brk;    /* aligned offset into brk */
  
    mchunkptr       p;              /* the allocated/returned chunk */
    mchunkptr       remainder;      /* remainder from allocation */
    unsigned long   remainder_size; /* its size */
  
    unsigned long   sum;            /* for updating stats */
  
    size_t          pagemask  = av->pagesize - 1;
  
  
  #if HAVE_MMAP
  
    /*
      If have mmap, and the request size meets the mmap threshold, and
      the system supports mmap, and there are few enough currently
      allocated mmapped regions, try to directly map this request
      rather than expanding top.
    */
  
    if ((unsigned long)(nb) >= (unsigned long)(av->mmap_threshold) &&
        (av->n_mmaps < av->n_mmaps_max)) {
  
      char* mm;             /* return value from mmap call*/
  
      /*
        Round up size to nearest page.  For mmapped chunks, the overhead
        is one SIZE_SZ unit larger than for normal chunks, because there
        is no following chunk whose prev_size field could be used.
      */
      size = (nb + SIZE_SZ + MALLOC_ALIGN_MASK + pagemask) & ~pagemask;
  
      /* Don't try if size wraps around 0 */
      if ((unsigned long)(size) > (unsigned long)(nb)) {
  
        mm = (char*)(MMAP(0, size, PROT_READ|PROT_WRITE, MAP_PRIVATE));
        
        if (mm != (char*)(MORECORE_FAILURE)) {
          
          /*
            The offset to the start of the mmapped region is stored
            in the prev_size field of the chunk. This allows us to adjust
            returned start address to meet alignment requirements here 
            and in memalign(), and still be able to compute proper
            address argument for later munmap in free() and realloc().
          */
          
          front_misalign = (INTERNAL_SIZE_T)chunk2mem(mm) & MALLOC_ALIGN_MASK;
          if (front_misalign > 0) {
            correction = MALLOC_ALIGNMENT - front_misalign;
            p = (mchunkptr)(mm + correction);
            p->prev_size = correction;
            set_head(p, (size - correction) |IS_MMAPPED);
          }
          else {
            p = (mchunkptr)mm;
            set_head(p, size|IS_MMAPPED);
          }
          
          /* update statistics */
          
          if (++av->n_mmaps > av->max_n_mmaps) 
            av->max_n_mmaps = av->n_mmaps;
          
          sum = av->mmapped_mem += size;
          if (sum > (unsigned long)(av->max_mmapped_mem)) 
            av->max_mmapped_mem = sum;
          sum += av->sbrked_mem;
          if (sum > (unsigned long)(av->max_total_mem)) 
            av->max_total_mem = sum;
  
          check_chunk(p);
          
          return chunk2mem(p);
        }
      }
    }
  #endif
  
    /* Record incoming configuration of top */
  
    old_top  = av->top;
    old_size = chunksize(old_top);
    old_end  = (char*)(chunk_at_offset(old_top, old_size));
  
    brk = snd_brk = (char*)(MORECORE_FAILURE); 
  
    /* 
       If not the first time through, we require old_size to be
       at least MINSIZE and to have prev_inuse set.
    */
  
    assert((old_top == initial_top(av) && old_size == 0) || 
           ((unsigned long) (old_size) >= MINSIZE &&
            prev_inuse(old_top)));
  
    /* Precondition: not enough current space to satisfy nb request */
    assert((unsigned long)(old_size) < (unsigned long)(nb + MINSIZE));
  
    /* Precondition: all fastbins are consolidated */
    assert(!have_fastchunks(av));
  
  
    /* Request enough space for nb + pad + overhead */
  
    size = nb + av->top_pad + MINSIZE;
  
    /*
      If contiguous, we can subtract out existing space that we hope to
      combine with new space. We add it back later only if
      we don't actually get contiguous space.
    */
  
    if (contiguous(av))
      size -= old_size;
  
    /*
      Round to a multiple of page size.
      If MORECORE is not contiguous, this ensures that we only call it
      with whole-page arguments.  And if MORECORE is contiguous and
      this is not first time through, this preserves page-alignment of
      previous calls. Otherwise, we correct to page-align below.
    */
  
    size = (size + pagemask) & ~pagemask;
  
    /*
      Don't try to call MORECORE if argument is so big as to appear
      negative. Note that since mmap takes size_t arg, it may succeed
      below even if we cannot call MORECORE.
    */
  
    if (size > 0) 
      brk = (char*)(MORECORE(size));
  
    /*
      If have mmap, try using it as a backup when MORECORE fails or
      cannot be used. This is worth doing on systems that have "holes" in
      address space, so sbrk cannot extend to give contiguous space, but
      space is available elsewhere.  Note that we ignore mmap max count
      and threshold limits, since the space will not be used as a
      segregated mmap region.
    */
  
  #if HAVE_MMAP
    if (brk == (char*)(MORECORE_FAILURE)) {
  
      /* Cannot merge with old top, so add its size back in */
      if (contiguous(av))
        size = (size + old_size + pagemask) & ~pagemask;
  
      /* If we are relying on mmap as backup, then use larger units */
      if ((unsigned long)(size) < (unsigned long)(MMAP_AS_MORECORE_SIZE))
        size = MMAP_AS_MORECORE_SIZE;
  
      /* Don't try if size wraps around 0 */
      if ((unsigned long)(size) > (unsigned long)(nb)) {
  
        brk = (char*)(MMAP(0, size, PROT_READ|PROT_WRITE, MAP_PRIVATE));
        
        if (brk != (char*)(MORECORE_FAILURE)) {
          
          /* We do not need, and cannot use, another sbrk call to find end */
          snd_brk = brk + size;
          
          /* 
             Record that we no longer have a contiguous sbrk region. 
             After the first time mmap is used as backup, we do not
             ever rely on contiguous space since this could incorrectly
             bridge regions.
          */
          set_noncontiguous(av);
        }
      }
    }
  #endif
  
    if (brk != (char*)(MORECORE_FAILURE)) {
      av->sbrked_mem += size;
  
      /*
        If MORECORE extends previous space, we can likewise extend top size.
      */
      
      if (brk == old_end && snd_brk == (char*)(MORECORE_FAILURE)) {
        set_head(old_top, (size + old_size) | PREV_INUSE);
      }
      
      /*
        Otherwise, make adjustments:
        
        * If the first time through or noncontiguous, we need to call sbrk
          just to find out where the end of memory lies.
  
        * We need to ensure that all returned chunks from malloc will meet
          MALLOC_ALIGNMENT
  
        * If there was an intervening foreign sbrk, we need to adjust sbrk
          request size to account for fact that we will not be able to
          combine new space with existing space in old_top.
  
        * Almost all systems internally allocate whole pages at a time, in
          which case we might as well use the whole last page of request.
          So we allocate enough more memory to hit a page boundary now,
          which in turn causes future contiguous calls to page-align.
      */
      
      else {
        front_misalign = 0;
        end_misalign = 0;
        correction = 0;
        aligned_brk = brk;
        
        /* handle contiguous cases */
        if (contiguous(av)) { 
          
          /* Guarantee alignment of first new chunk made from this space */
  
          front_misalign = (INTERNAL_SIZE_T)chunk2mem(brk) & MALLOC_ALIGN_MASK;
          if (front_misalign > 0) {
  
            /*
              Skip over some bytes to arrive at an aligned position.
              We don't need to specially mark these wasted front bytes.
              They will never be accessed anyway because
              prev_inuse of av->top (and any chunk created from its start)
              is always true after initialization.
            */
  
            correction = MALLOC_ALIGNMENT - front_misalign;
            aligned_brk += correction;
          }
          
          /*
            If this isn't adjacent to existing space, then we will not
            be able to merge with old_top space, so must add to 2nd request.
          */
          
          correction += old_size;
          
          /* Extend the end address to hit a page boundary */
          end_misalign = (INTERNAL_SIZE_T)(brk + size + correction);
          correction += ((end_misalign + pagemask) & ~pagemask) - end_misalign;
          
          assert(correction >= 0);
          snd_brk = (char*)(MORECORE(correction));
          
          /*
            If can't allocate correction, try to at least find out current
            brk.  It might be enough to proceed without failing.
            
            Note that if second sbrk did NOT fail, we assume that space
            is contiguous with first sbrk. This is a safe assumption unless
            program is multithreaded but doesn't use locks and a foreign sbrk
            occurred between our first and second calls.
          */
          
          if (snd_brk == (char*)(MORECORE_FAILURE)) {
            correction = 0;
            snd_brk = (char*)(MORECORE(0));
          }
        }
        
        /* handle non-contiguous cases */
        else { 
          /* MORECORE/mmap must correctly align */
          assert(((unsigned long)chunk2mem(brk) & MALLOC_ALIGN_MASK) == 0);
          
          /* Find out current end of memory */
          if (snd_brk == (char*)(MORECORE_FAILURE)) {
            snd_brk = (char*)(MORECORE(0));
          }
        }
        
        /* Adjust top based on results of second sbrk */
        if (snd_brk != (char*)(MORECORE_FAILURE)) {
          av->top = (mchunkptr)aligned_brk;
          set_head(av->top, (snd_brk - aligned_brk + correction) | PREV_INUSE);
          av->sbrked_mem += correction;
       
          /*
            If not the first time through, we either have a
            gap due to foreign sbrk or a non-contiguous region.  Insert a
            double fencepost at old_top to prevent consolidation with space
            we don't own. These fenceposts are artificial chunks that are
            marked as inuse and are in any case too small to use.  We need
            two to make sizes and alignments work out.
          */
     
          if (old_size != 0) {
            /* 
               Shrink old_top to insert fenceposts, keeping size a
               multiple of MALLOC_ALIGNMENT. We know there is at least
               enough space in old_top to do this.
            */
            old_size = (old_size - 3*SIZE_SZ) & ~MALLOC_ALIGN_MASK;
            set_head(old_top, old_size | PREV_INUSE);
            
            /*
              Note that the following assignments completely overwrite
              old_top when old_size was previously MINSIZE.  This is
              intentional. We need the fencepost, even if old_top otherwise gets
              lost.
            */
            chunk_at_offset(old_top, old_size          )->size =
              SIZE_SZ|PREV_INUSE;
  
            chunk_at_offset(old_top, old_size + SIZE_SZ)->size =
              SIZE_SZ|PREV_INUSE;
  
            /* If possible, release the rest. */
            if (old_size >= MINSIZE) {
              fREe(chunk2mem(old_top));
            }
  
          }
        }
      }
      
      /* Update statistics */
      sum = av->sbrked_mem;
      if (sum > (unsigned long)(av->max_sbrked_mem))
        av->max_sbrked_mem = sum;
      
      sum += av->mmapped_mem;
      if (sum > (unsigned long)(av->max_total_mem))
        av->max_total_mem = sum;
  
      check_malloc_state();
      
      /* finally, do the allocation */
      p = av->top;
      size = chunksize(p);
      
      /* check that one of the above allocation paths succeeded */
      if ((unsigned long)(size) >= (unsigned long)(nb + MINSIZE)) {
        remainder_size = size - nb;
        remainder = chunk_at_offset(p, nb);
        av->top = remainder;
        set_head(p, nb | PREV_INUSE);
        set_head(remainder, remainder_size | PREV_INUSE);
        check_malloced_chunk(p, nb);
        return chunk2mem(p);
      }
    }
  
    /* catch all failure paths */
    MALLOC_FAILURE_ACTION;
    return 0;
  }
  
  
  /*
    sYSTRIm is an inverse of sorts to sYSMALLOc.  It gives memory back
    to the system (via negative arguments to sbrk) if there is unused
    memory at the `high' end of the malloc pool. It is called
    automatically by free() when top space exceeds the trim
    threshold. It is also called by the public malloc_trim routine.  It
    returns 1 if it actually released any memory, else 0.
  */
  
  #if __STD_C
  static int sYSTRIm(size_t pad, mstate av)
  #else
  static int sYSTRIm(pad, av) size_t pad; mstate av;
  #endif
  {
    long  top_size;        /* Amount of top-most memory */
    long  extra;           /* Amount to release */
    long  released;        /* Amount actually released */
    char* current_brk;     /* address returned by pre-check sbrk call */
    char* new_brk;         /* address returned by post-check sbrk call */
    size_t pagesz;
  
    pagesz = av->pagesize;
    top_size = chunksize(av->top);
    
    /* Release in pagesize units, keeping at least one page */
    extra = ((top_size - pad - MINSIZE + (pagesz-1)) / pagesz - 1) * pagesz;
    
    if (extra > 0) {
      
      /*
        Only proceed if end of memory is where we last set it.
        This avoids problems if there were foreign sbrk calls.
      */
      current_brk = (char*)(MORECORE(0));
      if (current_brk == (char*)(av->top) + top_size) {
        
        /*
          Attempt to release memory. We ignore MORECORE return value,
          and instead call again to find out where new end of memory is.
          This avoids problems if first call releases less than we asked,
          of if failure somehow altered brk value. (We could still
          encounter problems if it altered brk in some very bad way,
          but the only thing we can do is adjust anyway, which will cause
          some downstream failure.)
        */
        
        MORECORE(-extra);
        new_brk = (char*)(MORECORE(0));
        
        if (new_brk != (char*)MORECORE_FAILURE) {
          released = (long)(current_brk - new_brk);
          
          if (released != 0) {
            /* Success. Adjust top. */
            av->sbrked_mem -= released;
            set_head(av->top, (top_size - released) | PREV_INUSE);
            check_malloc_state();
            return 1;
          }
        }
      }
    }
    return 0;
  }
  
  /*
    ------------------------------ malloc ------------------------------
  */
  
  #if __STD_C
  Void_t* mALLOc(size_t bytes)
  #else
    Void_t* mALLOc(bytes) size_t bytes;
  #endif
  {
    mstate av = get_malloc_state();
  
    INTERNAL_SIZE_T nb;               /* normalized request size */
    unsigned int    idx;              /* associated bin index */
    mbinptr         bin;              /* associated bin */
    mfastbinptr*    fb;               /* associated fastbin */
  
    mchunkptr       victim;           /* inspected/selected chunk */
    INTERNAL_SIZE_T size;             /* its size */
    int             victim_index;     /* its bin index */
  
    mchunkptr       remainder;        /* remainder from a split */
    unsigned long   remainder_size;   /* its size */
  
    unsigned int    block;            /* bit map traverser */
    unsigned int    bit;              /* bit map traverser */
    unsigned int    map;              /* current word of binmap */
  
    mchunkptr       fwd;              /* misc temp for linking */
    mchunkptr       bck;              /* misc temp for linking */
  
    /*
      Convert request size to internal form by adding SIZE_SZ bytes
      overhead plus possibly more to obtain necessary alignment and/or
      to obtain a size of at least MINSIZE, the smallest allocatable
      size. Also, checked_request2size traps (returning 0) request sizes
      that are so large that they wrap around zero when padded and
      aligned.
    */
  
    checked_request2size(bytes, nb);
  
    /*
      If the size qualifies as a fastbin, first check corresponding bin.
      This code is safe to execute even if av is not yet initialized, so we
      can try it without checking, which saves some time on this fast path.
    */
  
    if ((unsigned long)(nb) <= (unsigned long)(av->max_fast)) { 
      fb = &(av->fastbins[(fastbin_index(nb))]);
      if ( (victim = *fb) != 0) {
        *fb = victim->fd;
        check_remalloced_chunk(victim, nb);
        return chunk2mem(victim);
      }
    }
  
    /*
      If a small request, check regular bin.  Since these "smallbins"
      hold one size each, no searching within bins is necessary.
      (For a large request, we need to wait until unsorted chunks are
      processed to find best fit. But for small ones, fits are exact
      anyway, so we can check now, which is faster.)
    */
  
    if (in_smallbin_range(nb)) {
      idx = smallbin_index(nb);
      bin = bin_at(av,idx);
  
      if ( (victim = last(bin)) != bin) {
        if (victim == 0) /* initialization check */
          malloc_consolidate(av);
        else {
          bck = victim->bk;
          set_inuse_bit_at_offset(victim, nb);
          bin->bk = bck;
          bck->fd = bin;
          
          check_malloced_chunk(victim, nb);
          return chunk2mem(victim);
        }
      }
    }
  
    /* 
       If this is a large request, consolidate fastbins before continuing.
       While it might look excessive to kill all fastbins before
       even seeing if there is space available, this avoids
       fragmentation problems normally associated with fastbins.
       Also, in practice, programs tend to have runs of either small or
       large requests, but less often mixtures, so consolidation is not 
       invoked all that often in most programs. And the programs that
       it is called frequently in otherwise tend to fragment.
    */
  
    else {
      idx = largebin_index(nb);
      if (have_fastchunks(av)) 
        malloc_consolidate(av);
    }
  
    /*
      Process recently freed or remaindered chunks, taking one only if
      it is exact fit, or, if this a small request, the chunk is remainder from
      the most recent non-exact fit.  Place other traversed chunks in
      bins.  Note that this step is the only place in any routine where
      chunks are placed in bins.
  
      The outer loop here is needed because we might not realize until
      near the end of malloc that we should have consolidated, so must
      do so and retry. This happens at most once, and only when we would
      otherwise need to expand memory to service a "small" request.
    */
      
    for(;;) {    
      
      while ( (victim = unsorted_chunks(av)->bk) != unsorted_chunks(av)) {
        bck = victim->bk;
        size = chunksize(victim);
  
        /* 
           If a small request, try to use last remainder if it is the
           only chunk in unsorted bin.  This helps promote locality for
           runs of consecutive small requests. This is the only
           exception to best-fit, and applies only when there is
           no exact fit for a small chunk.
        */
  
        if (in_smallbin_range(nb) && 
            bck == unsorted_chunks(av) &&
            victim == av->last_remainder &&
            (unsigned long)(size) > (unsigned long)(nb + MINSIZE)) {
  
          /* split and reattach remainder */
          remainder_size = size - nb;
          remainder = chunk_at_offset(victim, nb);
          unsorted_chunks(av)->bk = unsorted_chunks(av)->fd = remainder;
          av->last_remainder = remainder; 
          remainder->bk = remainder->fd = unsorted_chunks(av);
          
          set_head(victim, nb | PREV_INUSE);
          set_head(remainder, remainder_size | PREV_INUSE);
          set_foot(remainder, remainder_size);
          
          check_malloced_chunk(victim, nb);
          return chunk2mem(victim);
        }
  
        /* remove from unsorted list */
        unsorted_chunks(av)->bk = bck;
        bck->fd = unsorted_chunks(av);
        
        /* Take now instead of binning if exact fit */
        
        if (size == nb) {
          set_inuse_bit_at_offset(victim, size);
          check_malloced_chunk(victim, nb);
          return chunk2mem(victim);
        }
        
        /* place chunk in bin */
        
        if (in_smallbin_range(size)) {
          victim_index = smallbin_index(size);
          bck = bin_at(av, victim_index);
          fwd = bck->fd;
        }
        else {
          victim_index = largebin_index(size);
          bck = bin_at(av, victim_index);
          fwd = bck->fd;
  
          /* maintain large bins in sorted order */
          if (fwd != bck) {
            size |= PREV_INUSE; /* Or with inuse bit to speed comparisons */
            /* if smaller than smallest, bypass loop below */
            if ((unsigned long)(size) <= (unsigned long)(bck->bk->size)) {
              fwd = bck;
              bck = bck->bk;
            }
            else {
              while ((unsigned long)(size) < (unsigned long)(fwd->size)) 
                fwd = fwd->fd;
              bck = fwd->bk;
            }
          }
        }
        
        mark_bin(av, victim_index);
        victim->bk = bck;
        victim->fd = fwd;
        fwd->bk = victim;
        bck->fd = victim;
      }
     
      /*
        If a large request, scan through the chunks of current bin in
        sorted order to find smallest that fits.  This is the only step
        where an unbounded number of chunks might be scanned without doing
        anything useful with them. However the lists tend to be short.
      */
        
      if (!in_smallbin_range(nb)) {
        bin = bin_at(av, idx);
  
        /* skip scan if empty or largest chunk is too small */
        if ((victim = last(bin)) != bin &&
            (unsigned long)(first(bin)->size) >= (unsigned long)(nb)) {
  
          while (((unsigned long)(size = chunksize(victim)) < 
                  (unsigned long)(nb)))
            victim = victim->bk;
  
          remainder_size = size - nb;
          unlink(victim, bck, fwd);
          
          /* Exhaust */
          if (remainder_size < MINSIZE)  {
            set_inuse_bit_at_offset(victim, size);
            check_malloced_chunk(victim, nb);
            return chunk2mem(victim);
          }
          /* Split */
          else {
            remainder = chunk_at_offset(victim, nb);
            unsorted_chunks(av)->bk = unsorted_chunks(av)->fd = remainder;
            remainder->bk = remainder->fd = unsorted_chunks(av);
            set_head(victim, nb | PREV_INUSE);
            set_head(remainder, remainder_size | PREV_INUSE);
            set_foot(remainder, remainder_size);
            check_malloced_chunk(victim, nb);
            return chunk2mem(victim);
          } 
        }
      }    
  
      /*
        Search for a chunk by scanning bins, starting with next largest
        bin. This search is strictly by best-fit; i.e., the smallest
        (with ties going to approximately the least recently used) chunk
        that fits is selected.
        
        The bitmap avoids needing to check that most blocks are nonempty.
        The particular case of skipping all bins during warm-up phases
        when no chunks have been returned yet is faster than it might look.
      */
      
      ++idx;
      bin = bin_at(av,idx);
      block = idx2block(idx);
      map = av->binmap[block];
      bit = idx2bit(idx);
      
      for (;;) {
  
        /* Skip rest of block if there are no more set bits in this block.  */
        if (bit > map || bit == 0) {
          do {
            if (++block >= BINMAPSIZE)  /* out of bins */
              goto use_top;
          } while ( (map = av->binmap[block]) == 0);
  
          bin = bin_at(av, (block << BINMAPSHIFT));
          bit = 1;
        }
        
        /* Advance to bin with set bit. There must be one. */
        while ((bit & map) == 0) {
          bin = next_bin(bin);
          bit <<= 1;
          assert(bit != 0);
        }
        
        /* Inspect the bin. It is likely to be non-empty */
        victim = last(bin);
        
        /*  If a false alarm (empty bin), clear the bit. */
        if (victim == bin) {
          av->binmap[block] = map &= ~bit; /* Write through */
          bin = next_bin(bin);
          bit <<= 1;
        }
        
        else {
          size = chunksize(victim);
  
          /*  We know the first chunk in this bin is big enough to use. */
          assert((unsigned long)(size) >= (unsigned long)(nb));
  
          remainder_size = size - nb;
          
          /* unlink */
          bck = victim->bk;
          bin->bk = bck;
          bck->fd = bin;
          
          /* Exhaust */
          if (remainder_size < MINSIZE) {
            set_inuse_bit_at_offset(victim, size);
            check_malloced_chunk(victim, nb);
            return chunk2mem(victim);
          }
          
          /* Split */
          else {
            remainder = chunk_at_offset(victim, nb);
            
            unsorted_chunks(av)->bk = unsorted_chunks(av)->fd = remainder;
            remainder->bk = remainder->fd = unsorted_chunks(av);
            /* advertise as last remainder */
            if (in_smallbin_range(nb)) 
              av->last_remainder = remainder; 
            
            set_head(victim, nb | PREV_INUSE);
            set_head(remainder, remainder_size | PREV_INUSE);
            set_foot(remainder, remainder_size);
            check_malloced_chunk(victim, nb);
            return chunk2mem(victim);
          }
        }
      }
  
    use_top:    
      /*
        If large enough, split off the chunk bordering the end of memory
        (held in av->top). Note that this is in accord with the best-fit
        search rule.  In effect, av->top is treated as larger (and thus
        less well fitting) than any other available chunk since it can
        be extended to be as large as necessary (up to system
        limitations).
  
        We require that av->top always exists (i.e., has size >=
        MINSIZE) after initialization, so if it would otherwise be
        exhuasted by current request, it is replenished. (The main
        reason for ensuring it exists is that we may need MINSIZE space
        to put in fenceposts in sysmalloc.)
      */
  
      victim = av->top;
      size = chunksize(victim);
     
      if ((unsigned long)(size) >= (unsigned long)(nb + MINSIZE)) {
        remainder_size = size - nb;
        remainder = chunk_at_offset(victim, nb);
        av->top = remainder;
        set_head(victim, nb | PREV_INUSE);
        set_head(remainder, remainder_size | PREV_INUSE);
  
        check_malloced_chunk(victim, nb);
        return chunk2mem(victim);
      }
  
      /*
        If there is space available in fastbins, consolidate and retry,
        to possibly avoid expanding memory. This can occur only if nb is
        in smallbin range so we didn't consolidate upon entry.
      */
  
      else if (have_fastchunks(av)) {
        assert(in_smallbin_range(nb));
        malloc_consolidate(av);
        idx = smallbin_index(nb); /* restore original bin index */
      }
  
      /* 
         Otherwise, relay to handle system-dependent cases 
      */
      else 
        return sYSMALLOc(nb, av);    
    }
  }
  
  /*
    ------------------------------ free ------------------------------
  */
  
  #if __STD_C
  void fREe(Void_t* mem)
  #else
  void fREe(mem) Void_t* mem;
  #endif
  {
    mstate av = get_malloc_state();
  
    mchunkptr       p;           /* chunk corresponding to mem */
    INTERNAL_SIZE_T size;        /* its size */
    mfastbinptr*    fb;          /* associated fastbin */
    mchunkptr       nextchunk;   /* next contiguous chunk */
    INTERNAL_SIZE_T nextsize;    /* its size */
    int             nextinuse;   /* true if nextchunk is used */
    INTERNAL_SIZE_T prevsize;    /* size of previous contiguous chunk */
    mchunkptr       bck;         /* misc temp for linking */
    mchunkptr       fwd;         /* misc temp for linking */
  
  
    /* free(0) has no effect */
    if (mem != 0) {
      p = mem2chunk(mem);
      size = chunksize(p);
  
      check_inuse_chunk(p);
  
      /*
        If eligible, place chunk on a fastbin so it can be found
        and used quickly in malloc.
      */
  
      if ((unsigned long)(size) <= (unsigned long)(av->max_fast)
  
  #if TRIM_FASTBINS
          /* 
             If TRIM_FASTBINS set, don't place chunks
             bordering top into fastbins
          */
          && (chunk_at_offset(p, size) != av->top)
  #endif
          ) {
  
        set_fastchunks(av);
        fb = &(av->fastbins[fastbin_index(size)]);
        p->fd = *fb;
        *fb = p;
      }
  
      /*
         Consolidate other non-mmapped chunks as they arrive.
      */
  
      else if (!chunk_is_mmapped(p)) {
        nextchunk = chunk_at_offset(p, size);
        nextsize = chunksize(nextchunk);
  
        /* consolidate backward */
        if (!prev_inuse(p)) {
          prevsize = p->prev_size;
          size += prevsize;
          p = chunk_at_offset(p, -((long) prevsize));
          unlink(p, bck, fwd);
        }
  
        if (nextchunk != av->top) {
          /* get and clear inuse bit */
          nextinuse = inuse_bit_at_offset(nextchunk, nextsize);
          set_head(nextchunk, nextsize);
  
          /* consolidate forward */
          if (!nextinuse) {
            unlink(nextchunk, bck, fwd);
            size += nextsize;
          }
  
          /*
            Place the chunk in unsorted chunk list. Chunks are
            not placed into regular bins until after they have
            been given one chance to be used in malloc.
          */
  
          bck = unsorted_chunks(av);
          fwd = bck->fd;
          p->bk = bck;
          p->fd = fwd;
          bck->fd = p;
          fwd->bk = p;
  
          set_head(p, size | PREV_INUSE);
          set_foot(p, size);
          
          check_free_chunk(p);
        }
  
        /*
           If the chunk borders the current high end of memory,
           consolidate into top
        */
  
        else {
          size += nextsize;
          set_head(p, size | PREV_INUSE);
          av->top = p;
          check_chunk(p);
        }
  
        /*
          If freeing a large space, consolidate possibly-surrounding
          chunks. Then, if the total unused topmost memory exceeds trim
          threshold, ask malloc_trim to reduce top.
  
          Unless max_fast is 0, we don't know if there are fastbins
          bordering top, so we cannot tell for sure whether threshold
          has been reached unless fastbins are consolidated.  But we
          don't want to consolidate on each free.  As a compromise,
          consolidation is performed if FASTBIN_CONSOLIDATION_THRESHOLD
          is reached.
        */
  
        if ((unsigned long)(size) >= FASTBIN_CONSOLIDATION_THRESHOLD) { 
          if (have_fastchunks(av)) 
            malloc_consolidate(av);
  
  #ifndef MORECORE_CANNOT_TRIM        
          if ((unsigned long)(chunksize(av->top)) >= 
              (unsigned long)(av->trim_threshold)) 
            sYSTRIm(av->top_pad, av);
  #endif
        }
  
      }
      /*
        If the chunk was allocated via mmap, release via munmap()
        Note that if HAVE_MMAP is false but chunk_is_mmapped is
        true, then user must have overwritten memory. There's nothing
        we can do to catch this error unless DEBUG is set, in which case
        check_inuse_chunk (above) will have triggered error.
      */
  
      else {
  #if HAVE_MMAP
        int ret;
        INTERNAL_SIZE_T offset = p->prev_size;
        av->n_mmaps--;
        av->mmapped_mem -= (size + offset);
        ret = munmap((char*)p - offset, size + offset);
        /* munmap returns non-zero on failure */
        assert(ret == 0);
  #endif
      }
    }
  }
  
  /*
    ------------------------- malloc_consolidate -------------------------
  
    malloc_consolidate is a specialized version of free() that tears
    down chunks held in fastbins.  Free itself cannot be used for this
    purpose since, among other things, it might place chunks back onto
    fastbins.  So, instead, we need to use a minor variant of the same
    code.
    
    Also, because this routine needs to be called the first time through
    malloc anyway, it turns out to be the perfect place to trigger
    initialization code.
  */
  
  #if __STD_C
  static void malloc_consolidate(mstate av)
  #else
  static void malloc_consolidate(av) mstate av;
  #endif
  {
    mfastbinptr*    fb;                 /* current fastbin being consolidated */
    mfastbinptr*    maxfb;              /* last fastbin (for loop control) */
    mchunkptr       p;                  /* current chunk being consolidated */
    mchunkptr       nextp;              /* next chunk to consolidate */
    mchunkptr       unsorted_bin;       /* bin header */
    mchunkptr       first_unsorted;     /* chunk to link to */
  
    /* These have same use as in free() */
    mchunkptr       nextchunk;
    INTERNAL_SIZE_T size;
    INTERNAL_SIZE_T nextsize;
    INTERNAL_SIZE_T prevsize;
    int             nextinuse;
    mchunkptr       bck;
    mchunkptr       fwd;
  
    /*
      If max_fast is 0, we know that av hasn't
      yet been initialized, in which case do so below
    */
  
    if (av->max_fast != 0) {
      clear_fastchunks(av);
  
      unsorted_bin = unsorted_chunks(av);
  
      /*
        Remove each chunk from fast bin and consolidate it, placing it
        then in unsorted bin. Among other reasons for doing this,
        placing in unsorted bin avoids needing to calculate actual bins
        until malloc is sure that chunks aren't immediately going to be
        reused anyway.
      */
      
      maxfb = &(av->fastbins[fastbin_index(av->max_fast)]);
      fb = &(av->fastbins[0]);
      do {
        if ( (p = *fb) != 0) {
          *fb = 0;
          
          do {
            check_inuse_chunk(p);
            nextp = p->fd;
            
            /* Slightly streamlined version of consolidation code in free() */
            size = p->size & ~PREV_INUSE;
            nextchunk = chunk_at_offset(p, size);
            nextsize = chunksize(nextchunk);
            
            if (!prev_inuse(p)) {
              prevsize = p->prev_size;
              size += prevsize;
              p = chunk_at_offset(p, -((long) prevsize));
              unlink(p, bck, fwd);
            }
            
            if (nextchunk != av->top) {
              nextinuse = inuse_bit_at_offset(nextchunk, nextsize);
              set_head(nextchunk, nextsize);
              
              if (!nextinuse) {
                size += nextsize;
                unlink(nextchunk, bck, fwd);
              }
              
              first_unsorted = unsorted_bin->fd;
              unsorted_bin->fd = p;
              first_unsorted->bk = p;
              
              set_head(p, size | PREV_INUSE);
              p->bk = unsorted_bin;
              p->fd = first_unsorted;
              set_foot(p, size);
            }
            
            else {
              size += nextsize;
              set_head(p, size | PREV_INUSE);
              av->top = p;
            }
            
          } while ( (p = nextp) != 0);
          
        }
      } while (fb++ != maxfb);
    }
    else {
      malloc_init_state(av);
      check_malloc_state();
    }
  }
  
  /*
    ------------------------------ realloc ------------------------------
  */
  
  
  #if __STD_C
  Void_t* rEALLOc(Void_t* oldmem, size_t bytes)
  #else
  Void_t* rEALLOc(oldmem, bytes) Void_t* oldmem; size_t bytes;
  #endif
  {
    mstate av = get_malloc_state();
  
    INTERNAL_SIZE_T  nb;              /* padded request size */
  
    mchunkptr        oldp;            /* chunk corresponding to oldmem */
    INTERNAL_SIZE_T  oldsize;         /* its size */
  
    mchunkptr        newp;            /* chunk to return */
    INTERNAL_SIZE_T  newsize;         /* its size */
    Void_t*          newmem;          /* corresponding user mem */
  
    mchunkptr        next;            /* next contiguous chunk after oldp */
  
    mchunkptr        remainder;       /* extra space at end of newp */
    unsigned long    remainder_size;  /* its size */
  
    mchunkptr        bck;             /* misc temp for linking */
    mchunkptr        fwd;             /* misc temp for linking */
  
    unsigned long    copysize;        /* bytes to copy */
    unsigned int     ncopies;         /* INTERNAL_SIZE_T words to copy */
    INTERNAL_SIZE_T* s;               /* copy source */ 
    INTERNAL_SIZE_T* d;               /* copy destination */
  
  
  #ifdef REALLOC_ZERO_BYTES_FREES
    if (bytes == 0) {
      fREe(oldmem);
      return 0;
    }
  #endif
  
    /* realloc of null is supposed to be same as malloc */
    if (oldmem == 0) return mALLOc(bytes);
  
    checked_request2size(bytes, nb);
  
    oldp    = mem2chunk(oldmem);
    oldsize = chunksize(oldp);
  
    check_inuse_chunk(oldp);
  
    if (!chunk_is_mmapped(oldp)) {
  
      if ((unsigned long)(oldsize) >= (unsigned long)(nb)) {
        /* already big enough; split below */
        newp = oldp;
        newsize = oldsize;
      }
  
      else {
        next = chunk_at_offset(oldp, oldsize);
  
        /* Try to expand forward into top */
        if (next == av->top &&
            (unsigned long)(newsize = oldsize + chunksize(next)) >=
            (unsigned long)(nb + MINSIZE)) {
          set_head_size(oldp, nb);
          av->top = chunk_at_offset(oldp, nb);
          set_head(av->top, (newsize - nb) | PREV_INUSE);
          return chunk2mem(oldp);
        }
        
        /* Try to expand forward into next chunk;  split off remainder below */
        else if (next != av->top && 
                 !inuse(next) &&
                 (unsigned long)(newsize = oldsize + chunksize(next)) >=
                 (unsigned long)(nb)) {
          newp = oldp;
          unlink(next, bck, fwd);
        }
  
        /* allocate, copy, free */
        else {
          newmem = mALLOc(nb - MALLOC_ALIGN_MASK);
          if (newmem == 0)
            return 0; /* propagate failure */
        
          newp = mem2chunk(newmem);
          newsize = chunksize(newp);
          
          /*
            Avoid copy if newp is next chunk after oldp.
          */
          if (newp == next) {
            newsize += oldsize;
            newp = oldp;
          }
          else {
            /*
              Unroll copy of <= 36 bytes (72 if 8byte sizes)
              We know that contents have an odd number of
              INTERNAL_SIZE_T-sized words; minimally 3.
            */
            
            copysize = oldsize - SIZE_SZ;
            s = (INTERNAL_SIZE_T*)(oldmem);
            d = (INTERNAL_SIZE_T*)(newmem);
            ncopies = copysize / sizeof(INTERNAL_SIZE_T);
            assert(ncopies >= 3);
            
            if (ncopies > 9)
              MALLOC_COPY(d, s, copysize);
            
            else {
              *(d+0) = *(s+0);
              *(d+1) = *(s+1);
              *(d+2) = *(s+2);
              if (ncopies > 4) {
                *(d+3) = *(s+3);
                *(d+4) = *(s+4);
                if (ncopies > 6) {
                  *(d+5) = *(s+5);
                  *(d+6) = *(s+6);
                  if (ncopies > 8) {
                    *(d+7) = *(s+7);
                    *(d+8) = *(s+8);
                  }
                }
              }
            }
            
            fREe(oldmem);
            check_inuse_chunk(newp);
            return chunk2mem(newp);
          }
        }
      }
  
      /* If possible, free extra space in old or extended chunk */
  
      assert((unsigned long)(newsize) >= (unsigned long)(nb));
  
      remainder_size = newsize - nb;
  
      if (remainder_size < MINSIZE) { /* not enough extra to split off */
        set_head_size(newp, newsize);
        set_inuse_bit_at_offset(newp, newsize);
      }
      else { /* split remainder */
        remainder = chunk_at_offset(newp, nb);
        set_head_size(newp, nb);
        set_head(remainder, remainder_size | PREV_INUSE);
        /* Mark remainder as inuse so free() won't complain */
        set_inuse_bit_at_offset(remainder, remainder_size);
        fREe(chunk2mem(remainder)); 
      }
  
      check_inuse_chunk(newp);
      return chunk2mem(newp);
    }
  
    /*
      Handle mmap cases
    */
  
    else {
  #if HAVE_MMAP
  
  #if HAVE_MREMAP
      INTERNAL_SIZE_T offset = oldp->prev_size;
      size_t pagemask = av->pagesize - 1;
      char *cp;
      unsigned long sum;
      
      /* Note the extra SIZE_SZ overhead */
      newsize = (nb + offset + SIZE_SZ + pagemask) & ~pagemask;
  
      /* don't need to remap if still within same page */
      if (oldsize == newsize - offset) 
        return oldmem;
  
      cp = (char*)mremap((char*)oldp - offset, oldsize + offset, newsize, 1);
      
      if (cp != (char*)MORECORE_FAILURE) {
  
        newp = (mchunkptr)(cp + offset);
        set_head(newp, (newsize - offset)|IS_MMAPPED);
        
        assert(aligned_OK(chunk2mem(newp)));
        assert((newp->prev_size == offset));
        
        /* update statistics */
        sum = av->mmapped_mem += newsize - oldsize;
        if (sum > (unsigned long)(av->max_mmapped_mem)) 
          av->max_mmapped_mem = sum;
        sum += av->sbrked_mem;
        if (sum > (unsigned long)(av->max_total_mem)) 
          av->max_total_mem = sum;
        
        return chunk2mem(newp);
      }
  #endif
  
      /* Note the extra SIZE_SZ overhead. */
      if ((unsigned long)(oldsize) >= (unsigned long)(nb + SIZE_SZ)) 
        newmem = oldmem; /* do nothing */
      else {
        /* Must alloc, copy, free. */
        newmem = mALLOc(nb - MALLOC_ALIGN_MASK);
        if (newmem != 0) {
          MALLOC_COPY(newmem, oldmem, oldsize - 2*SIZE_SZ);
          fREe(oldmem);
        }
      }
      return newmem;
  
  #else 
      /* If !HAVE_MMAP, but chunk_is_mmapped, user must have overwritten mem */
      check_malloc_state();
      MALLOC_FAILURE_ACTION;
      return 0;
  #endif
    }
  }
  
  /*
    ------------------------------ memalign ------------------------------
  */
  
  #if __STD_C
  Void_t* mEMALIGn(size_t alignment, size_t bytes)
  #else
  Void_t* mEMALIGn(alignment, bytes) size_t alignment; size_t bytes;
  #endif
  {
    INTERNAL_SIZE_T nb;             /* padded  request size */
    char*           m;              /* memory returned by malloc call */
    mchunkptr       p;              /* corresponding chunk */
    char*           brk;            /* alignment point within p */
    mchunkptr       newp;           /* chunk to return */
    INTERNAL_SIZE_T newsize;        /* its size */
    INTERNAL_SIZE_T leadsize;       /* leading space before alignment point */
    mchunkptr       remainder;      /* spare room at end to split off */
    unsigned long   remainder_size; /* its size */
    INTERNAL_SIZE_T size;
  
    /* If need less alignment than we give anyway, just relay to malloc */
  
    if (alignment <= MALLOC_ALIGNMENT) return mALLOc(bytes);
  
    /* Otherwise, ensure that it is at least a minimum chunk size */
  
    if (alignment <  MINSIZE) alignment = MINSIZE;
  
    /* Make sure alignment is power of 2 (in case MINSIZE is not).  */
    if ((alignment & (alignment - 1)) != 0) {
      size_t a = MALLOC_ALIGNMENT * 2;
      while ((unsigned long)a < (unsigned long)alignment) a <<= 1;
      alignment = a;
    }
  
    checked_request2size(bytes, nb);
  
    /*
      Strategy: find a spot within that chunk that meets the alignment
      request, and then possibly free the leading and trailing space.
    */
  
  
    /* Call malloc with worst case padding to hit alignment. */
  
    m  = (char*)(mALLOc(nb + alignment + MINSIZE));
  
    if (m == 0) return 0; /* propagate failure */
  
    p = mem2chunk(m);
  
    if ((((unsigned long)(m)) % alignment) != 0) { /* misaligned */
  
      /*
        Find an aligned spot inside chunk.  Since we need to give back
        leading space in a chunk of at least MINSIZE, if the first
        calculation places us at a spot with less than MINSIZE leader,
        we can move to the next aligned spot -- we've allocated enough
        total room so that this is always possible.
      */
  
      brk = (char*)mem2chunk(((unsigned long)(m + alignment - 1)) &
                             -((signed long) alignment));
      if ((unsigned long)(brk - (char*)(p)) < MINSIZE)
        brk += alignment;
  
      newp = (mchunkptr)brk;
      leadsize = brk - (char*)(p);
      newsize = chunksize(p) - leadsize;
  
      /* For mmapped chunks, just adjust offset */
      if (chunk_is_mmapped(p)) {
        newp->prev_size = p->prev_size + leadsize;
        set_head(newp, newsize|IS_MMAPPED);
        return chunk2mem(newp);
      }
  
      /* Otherwise, give back leader, use the rest */
      set_head(newp, newsize | PREV_INUSE);
      set_inuse_bit_at_offset(newp, newsize);
      set_head_size(p, leadsize);
      fREe(chunk2mem(p));
      p = newp;
  
      assert (newsize >= nb &&
              (((unsigned long)(chunk2mem(p))) % alignment) == 0);
    }
  
    /* Also give back spare room at the end */
    if (!chunk_is_mmapped(p)) {
      size = chunksize(p);
      if ((unsigned long)(size) > (unsigned long)(nb + MINSIZE)) {
        remainder_size = size - nb;
        remainder = chunk_at_offset(p, nb);
        set_head(remainder, remainder_size | PREV_INUSE);
        set_head_size(p, nb);
        fREe(chunk2mem(remainder));
      }
    }
  
    check_inuse_chunk(p);
    return chunk2mem(p);
  }
  
  /*
    ------------------------------ calloc ------------------------------
  */
  
  #if __STD_C
  Void_t* cALLOc(size_t n_elements, size_t elem_size)
  #else
  Void_t* cALLOc(n_elements, elem_size) size_t n_elements; size_t elem_size;
  #endif
  {
    mchunkptr p;
    unsigned long clearsize;
    unsigned long nclears;
    INTERNAL_SIZE_T* d;
  
    Void_t* mem = mALLOc(n_elements * elem_size);
  
    if (mem != 0) {
      p = mem2chunk(mem);
  
  #if MMAP_CLEARS
      if (!chunk_is_mmapped(p)) /* don't need to clear mmapped space */
  #endif
      {  
        /*
          Unroll clear of <= 36 bytes (72 if 8byte sizes)
          We know that contents have an odd number of
          INTERNAL_SIZE_T-sized words; minimally 3.
        */
  
        d = (INTERNAL_SIZE_T*)mem;
        clearsize = chunksize(p) - SIZE_SZ;
        nclears = clearsize / sizeof(INTERNAL_SIZE_T);
        assert(nclears >= 3);
  
        if (nclears > 9)
          MALLOC_ZERO(d, clearsize);
  
        else {
          *(d+0) = 0;
          *(d+1) = 0;
          *(d+2) = 0;
          if (nclears > 4) {
            *(d+3) = 0;
            *(d+4) = 0;
            if (nclears > 6) {
              *(d+5) = 0;
              *(d+6) = 0;
              if (nclears > 8) {
                *(d+7) = 0;
                *(d+8) = 0;
              }
            }
          }
        }
      }
    }
    return mem;
  }
  
  /*
    ------------------------------ cfree ------------------------------
  */
  
  #if __STD_C
  void cFREe(Void_t *mem)
  #else
  void cFREe(mem) Void_t *mem;
  #endif
  {
    fREe(mem);
  }
  
  /*
    ------------------------- independent_calloc -------------------------
  */
  
  #if __STD_C
  Void_t** iCALLOc(size_t n_elements, size_t elem_size, Void_t* chunks[])
  #else
  Void_t** iCALLOc(n_elements, elem_size, chunks) size_t n_elements; size_t elem_size; Void_t* chunks[];
  #endif
  {
    size_t sz = elem_size; /* serves as 1-element array */
    /* opts arg of 3 means all elements are same size, and should be cleared */
    return iALLOc(n_elements, &sz, 3, chunks);
  }
  
  /*
    ------------------------- independent_comalloc -------------------------
  */
  
  #if __STD_C
  Void_t** iCOMALLOc(size_t n_elements, size_t sizes[], Void_t* chunks[])
  #else
  Void_t** iCOMALLOc(n_elements, sizes, chunks) size_t n_elements; size_t sizes[]; Void_t* chunks[];
  #endif
  {
    return iALLOc(n_elements, sizes, 0, chunks);
  }
  
  
  /*
    ------------------------------ ialloc ------------------------------
    ialloc provides common support for independent_X routines, handling all of
    the combinations that can result.
  
    The opts arg has:
      bit 0 set if all elements are same size (using sizes[0])
      bit 1 set if elements should be zeroed
  */
  
  
  #if __STD_C
  static Void_t** iALLOc(size_t n_elements, 
                         size_t* sizes,  
                         int opts,
                         Void_t* chunks[])
  #else
  static Void_t** iALLOc(n_elements, sizes, opts, chunks) size_t n_elements; size_t* sizes; int opts; Void_t* chunks[];
  #endif
  {
    mstate av = get_malloc_state();
    INTERNAL_SIZE_T element_size;   /* chunksize of each element, if all same */
    INTERNAL_SIZE_T contents_size;  /* total size of elements */
    INTERNAL_SIZE_T array_size;     /* request size of pointer array */
    Void_t*         mem;            /* malloced aggregate space */
    mchunkptr       p;              /* corresponding chunk */
    INTERNAL_SIZE_T remainder_size; /* remaining bytes while splitting */
    Void_t**        marray;         /* either "chunks" or malloced ptr array */
    mchunkptr       array_chunk;    /* chunk for malloced ptr array */
    int             mmx;            /* to disable mmap */
    INTERNAL_SIZE_T size;           
    size_t          i;
  
    /* Ensure initialization/consolidation */
    if (have_fastchunks(av)) malloc_consolidate(av);
  
    /* compute array length, if needed */
    if (chunks != 0) {
      if (n_elements == 0)
        return chunks; /* nothing to do */
      marray = chunks;
      array_size = 0;
    }
    else {
      /* if empty req, must still return chunk representing empty array */
      if (n_elements == 0) 
        return (Void_t**) mALLOc(0);
      marray = 0;
      array_size = request2size(n_elements * (sizeof(Void_t*)));
    }
  
    /* compute total element size */
    if (opts & 0x1) { /* all-same-size */
      element_size = request2size(*sizes);
      contents_size = n_elements * element_size;
    }
    else { /* add up all the sizes */
      element_size = 0;
      contents_size = 0;
      for (i = 0; i != n_elements; ++i) 
        contents_size += request2size(sizes[i]);     
    }
  
    /* subtract out alignment bytes from total to minimize overallocation */
    size = contents_size + array_size - MALLOC_ALIGN_MASK;
    
    /* 
       Allocate the aggregate chunk.
       But first disable mmap so malloc won't use it, since
       we would not be able to later free/realloc space internal
       to a segregated mmap region.
   */
    mmx = av->n_mmaps_max;   /* disable mmap */
    av->n_mmaps_max = 0;
    mem = mALLOc(size);
    av->n_mmaps_max = mmx;   /* reset mmap */
    if (mem == 0) 
      return 0;
  
    p = mem2chunk(mem);
    assert(!chunk_is_mmapped(p)); 
    remainder_size = chunksize(p);
  
    if (opts & 0x2) {       /* optionally clear the elements */
      MALLOC_ZERO(mem, remainder_size - SIZE_SZ - array_size);
    }
  
    /* If not provided, allocate the pointer array as final part of chunk */
    if (marray == 0) {
      array_chunk = chunk_at_offset(p, contents_size);
      marray = (Void_t**) (chunk2mem(array_chunk));
      set_head(array_chunk, (remainder_size - contents_size) | PREV_INUSE);
      remainder_size = contents_size;
    }
  
    /* split out elements */
    for (i = 0; ; ++i) {
      marray[i] = chunk2mem(p);
      if (i != n_elements-1) {
        if (element_size != 0) 
          size = element_size;
        else
          size = request2size(sizes[i]);          
        remainder_size -= size;
        set_head(p, size | PREV_INUSE);
        p = chunk_at_offset(p, size);
      }
      else { /* the final element absorbs any overallocation slop */
        set_head(p, remainder_size | PREV_INUSE);
        break;
      }
    }
  
  #if DEBUG
    if (marray != chunks) {
      /* final element must have exactly exhausted chunk */
      if (element_size != 0) 
        assert(remainder_size == element_size);
      else
        assert(remainder_size == request2size(sizes[i]));
      check_inuse_chunk(mem2chunk(marray));
    }
  
    for (i = 0; i != n_elements; ++i)
      check_inuse_chunk(mem2chunk(marray[i]));
  #endif
  
    return marray;
  }
  
  
  /*
    ------------------------------ valloc ------------------------------
  */
  
  #if __STD_C
  Void_t* vALLOc(size_t bytes)
  #else
  Void_t* vALLOc(bytes) size_t bytes;
  #endif
  {
    /* Ensure initialization/consolidation */
    mstate av = get_malloc_state();
    if (have_fastchunks(av)) malloc_consolidate(av);
    return mEMALIGn(av->pagesize, bytes);
  }
  
  /*
    ------------------------------ pvalloc ------------------------------
  */
  
  
  #if __STD_C
  Void_t* pVALLOc(size_t bytes)
  #else
  Void_t* pVALLOc(bytes) size_t bytes;
  #endif
  {
    mstate av = get_malloc_state();
    size_t pagesz;
  
    /* Ensure initialization/consolidation */
    if (have_fastchunks(av)) malloc_consolidate(av);
    pagesz = av->pagesize;
    return mEMALIGn(pagesz, (bytes + pagesz - 1) & ~(pagesz - 1));
  }
     
  
  /*
    ------------------------------ malloc_trim ------------------------------
  */
  
  #if __STD_C
  int mTRIm(size_t pad)
  #else
  int mTRIm(pad) size_t pad;
  #endif
  {
    mstate av = get_malloc_state();
    /* Ensure initialization/consolidation */
    malloc_consolidate(av);
  
  #ifndef MORECORE_CANNOT_TRIM        
    return sYSTRIm(pad, av);
  #else
    return 0;
  #endif
  }
  
  
  /*
    ------------------------- malloc_usable_size -------------------------
  */
  
  #if __STD_C
  size_t mUSABLe(Void_t* mem)
  #else
  size_t mUSABLe(mem) Void_t* mem;
  #endif
  {
    mchunkptr p;
    if (mem != 0) {
      p = mem2chunk(mem);
      if (chunk_is_mmapped(p))
        return chunksize(p) - 2*SIZE_SZ;
      else if (inuse(p))
        return chunksize(p) - SIZE_SZ;
    }
    return 0;
  }
  
  /*
    ------------------------------ mallinfo ------------------------------
  */
  
  struct mallinfo mALLINFo()
  {
    mstate av = get_malloc_state();
    struct mallinfo mi;
    int i;
    mbinptr b;
    mchunkptr p;
    INTERNAL_SIZE_T avail;
    INTERNAL_SIZE_T fastavail;
    int nblocks;
    int nfastblocks;
  
    /* Ensure initialization */
    if (av->top == 0)  malloc_consolidate(av);
  
    check_malloc_state();
  
    /* Account for top */
    avail = chunksize(av->top);
    nblocks = 1;  /* top always exists */
  
    /* traverse fastbins */
    nfastblocks = 0;
    fastavail = 0;
  
    for (i = 0; i < (int) NFASTBINS; ++i) {
      for (p = av->fastbins[i]; p != 0; p = p->fd) {
        ++nfastblocks;
        fastavail += chunksize(p);
      }
    }
  
    avail += fastavail;
  
    /* traverse regular bins */
    for (i = 1; i < NBINS; ++i) {
      b = bin_at(av, i);
      for (p = last(b); p != b; p = p->bk) {
        ++nblocks;
        avail += chunksize(p);
      }
    }
  
    mi.smblks = nfastblocks;
    mi.ordblks = nblocks;
    mi.fordblks = avail;
    mi.uordblks = av->sbrked_mem - avail;
    mi.arena = av->sbrked_mem;
    mi.hblks = av->n_mmaps;
    mi.hblkhd = av->mmapped_mem;
    mi.fsmblks = fastavail;
    mi.keepcost = chunksize(av->top);
    mi.usmblks = av->max_total_mem;
    return mi;
  }
  
  /*
    ------------------------------ malloc_stats ------------------------------
  */
  
  void mSTATs()
  {
    struct mallinfo mi = mALLINFo();
  
  #ifdef WIN32
    {
      unsigned long free, reserved, committed;
      vminfo (&free, &reserved, &committed);
      fprintf(stderr, "free bytes       = %10lu\n", 
              free);
      fprintf(stderr, "reserved bytes   = %10lu\n", 
              reserved);
      fprintf(stderr, "committed bytes  = %10lu\n", 
              committed);
    }
  #endif
  
  
    fprintf(stderr, "max system bytes = %10lu\n",
            (unsigned long)(mi.usmblks));
    fprintf(stderr, "system bytes     = %10lu\n",
            (unsigned long)(mi.arena + mi.hblkhd));
    fprintf(stderr, "in use bytes     = %10lu\n",
            (unsigned long)(mi.uordblks + mi.hblkhd));
  
  
  #ifdef WIN32 
    {
      unsigned long kernel, user;
      if (cpuinfo (TRUE, &kernel, &user)) {
        fprintf(stderr, "kernel ms        = %10lu\n", 
                kernel);
        fprintf(stderr, "user ms          = %10lu\n", 
                user);
      }
    }
  #endif
  }
  
  
  /*
    ------------------------------ mallopt ------------------------------
  */
  
  #if __STD_C
  int mALLOPt(int param_number, int value)
  #else
  int mALLOPt(param_number, value) int param_number; int value;
  #endif
  {
    mstate av = get_malloc_state();
    /* Ensure initialization/consolidation */
    malloc_consolidate(av);
  
    switch(param_number) {
    case M_MXFAST:
      if (value >= 0 && value <= MAX_FAST_SIZE) {
        set_max_fast(av, value);
        return 1;
      }
      else
        return 0;
  
    case M_TRIM_THRESHOLD:
      av->trim_threshold = value;
      return 1;
  
    case M_TOP_PAD:
      av->top_pad = value;
      return 1;
  
    case M_MMAP_THRESHOLD:
      av->mmap_threshold = value;
      return 1;
  
    case M_MMAP_MAX:
  #if !HAVE_MMAP
      if (value != 0)
        return 0;
  #endif
      av->n_mmaps_max = value;
      return 1;
  
    default:
      return 0;
    }
  }
  
  
  /* 
    -------------------- Alternative MORECORE functions --------------------
  */
  
  
  /*
    General Requirements for MORECORE.
  
    The MORECORE function must have the following properties:
  
    If MORECORE_CONTIGUOUS is false:
  
      * MORECORE must allocate in multiples of pagesize. It will
        only be called with arguments that are multiples of pagesize.
  
      * MORECORE(0) must return an address that is at least 
        MALLOC_ALIGNMENT aligned. (Page-aligning always suffices.)
  
    else (i.e. If MORECORE_CONTIGUOUS is true):
  
      * Consecutive calls to MORECORE with positive arguments
        return increasing addresses, indicating that space has been
        contiguously extended.
  
      * MORECORE need not allocate in multiples of pagesize.
        Calls to MORECORE need not have args of multiples of pagesize.
  
      * MORECORE need not page-align.
  
    In either case:
  
      * MORECORE may allocate more memory than requested. (Or even less,
        but this will generally result in a malloc failure.)
  
      * MORECORE must not allocate memory when given argument zero, but
        instead return one past the end address of memory from previous
        nonzero call. This malloc does NOT call MORECORE(0)
        until at least one call with positive arguments is made, so
        the initial value returned is not important.
  
      * Even though consecutive calls to MORECORE need not return contiguous
        addresses, it must be OK for malloc'ed chunks to span multiple
        regions in those cases where they do happen to be contiguous.
  
      * MORECORE need not handle negative arguments -- it may instead
        just return MORECORE_FAILURE when given negative arguments.
        Negative arguments are always multiples of pagesize. MORECORE
        must not misinterpret negative args as large positive unsigned
        args. You can suppress all such calls from even occurring by defining
        MORECORE_CANNOT_TRIM,
  
    There is some variation across systems about the type of the
    argument to sbrk/MORECORE. If size_t is unsigned, then it cannot
    actually be size_t, because sbrk supports negative args, so it is
    normally the signed type of the same width as size_t (sometimes
    declared as "intptr_t", and sometimes "ptrdiff_t").  It doesn't much
    matter though. Internally, we use "long" as arguments, which should
    work across all reasonable possibilities.
  
    Additionally, if MORECORE ever returns failure for a positive
    request, and HAVE_MMAP is true, then mmap is used as a noncontiguous
    system allocator. This is a useful backup strategy for systems with
    holes in address spaces -- in this case sbrk cannot contiguously
    expand the heap, but mmap may be able to map noncontiguous space.
  
    If you'd like mmap to ALWAYS be used, you can define MORECORE to be
    a function that always returns MORECORE_FAILURE.
  
    If you are using this malloc with something other than sbrk (or its
    emulation) to supply memory regions, you probably want to set
    MORECORE_CONTIGUOUS as false.  As an example, here is a custom
    allocator kindly contributed for pre-OSX macOS.  It uses virtually
    but not necessarily physically contiguous non-paged memory (locked
    in, present and won't get swapped out).  You can use it by
    uncommenting this section, adding some #includes, and setting up the
    appropriate defines above:
  
        #define MORECORE osMoreCore
        #define MORECORE_CONTIGUOUS 0
  
    There is also a shutdown routine that should somehow be called for
    cleanup upon program exit.
  
    #define MAX_POOL_ENTRIES 100
    #define MINIMUM_MORECORE_SIZE  (64 * 1024)
    static int next_os_pool;
    void *our_os_pools[MAX_POOL_ENTRIES];
  
    void *osMoreCore(int size)
    {
      void *ptr = 0;
      static void *sbrk_top = 0;
  
      if (size > 0)
      {
        if (size < MINIMUM_MORECORE_SIZE)
           size = MINIMUM_MORECORE_SIZE;
        if (CurrentExecutionLevel() == kTaskLevel)
           ptr = PoolAllocateResident(size + RM_PAGE_SIZE, 0);
        if (ptr == 0)
        {
          return (void *) MORECORE_FAILURE;
        }
        // save ptrs so they can be freed during cleanup
        our_os_pools[next_os_pool] = ptr;
        next_os_pool++;
        ptr = (void *) ((((unsigned long) ptr) + RM_PAGE_MASK) & ~RM_PAGE_MASK);
        sbrk_top = (char *) ptr + size;
        return ptr;
      }
      else if (size < 0)
      {
        // we don't currently support shrink behavior
        return (void *) MORECORE_FAILURE;
      }
      else
      {
        return sbrk_top;
      }
    }
  
    // cleanup any allocated memory pools
    // called as last thing before shutting down driver
  
    void osCleanupMem(void)
    {
      void **ptr;
  
      for (ptr = our_os_pools; ptr < &our_os_pools[MAX_POOL_ENTRIES]; ptr++)
        if (*ptr)
        {
           PoolDeallocate(*ptr);
           *ptr = 0;
        }
    }
  
  */
  
  
  /* 
    -------------------------------------------------------------- 
  
    Emulation of sbrk for win32. 
    Donated by J. Walter <Walter@GeNeSys-e.de>.
    For additional information about this code, and malloc on Win32, see 
       http://www.genesys-e.de/jwalter/
  */
  
  
  #ifdef WIN32
  
  #ifdef _DEBUG
  /* #define TRACE */
  #endif
  
  /* Support for USE_MALLOC_LOCK */
  #ifdef USE_MALLOC_LOCK
  
  /* Wait for spin lock */
  static int slwait (int *sl) {
      while (InterlockedCompareExchange ((void **) sl, (void *) 1, (void *) 0) != 0) 
  	    Sleep (0);
      return 0;
  }
  
  /* Release spin lock */
  static int slrelease (int *sl) {
      InterlockedExchange (sl, 0);
      return 0;
  }
  
  #ifdef NEEDED
  /* Spin lock for emulation code */
  static int g_sl;
  #endif
  
  #endif /* USE_MALLOC_LOCK */
  
  /* getpagesize for windows */
  static long getpagesize (void) {
      static long g_pagesize = 0;
      if (! g_pagesize) {
          SYSTEM_INFO system_info;
          GetSystemInfo (&system_info);
          g_pagesize = system_info.dwPageSize;
      }
      return g_pagesize;
  }
  static long getregionsize (void) {
      static long g_regionsize = 0;
      if (! g_regionsize) {
          SYSTEM_INFO system_info;
          GetSystemInfo (&system_info);
          g_regionsize = system_info.dwAllocationGranularity;
      }
      return g_regionsize;
  }
  
  /* A region list entry */
  typedef struct _region_list_entry {
      void *top_allocated;
      void *top_committed;
      void *top_reserved;
      long reserve_size;
      struct _region_list_entry *previous;
  } region_list_entry;
  
  /* Allocate and link a region entry in the region list */
  static int region_list_append (region_list_entry **last, void *base_reserved, long reserve_size) {
      region_list_entry *next = HeapAlloc (GetProcessHeap (), 0, sizeof (region_list_entry));
      if (! next)
          return FALSE;
      next->top_allocated = (char *) base_reserved;
      next->top_committed = (char *) base_reserved;
      next->top_reserved = (char *) base_reserved + reserve_size;
      next->reserve_size = reserve_size;
      next->previous = *last;
      *last = next;
      return TRUE;
  }
  /* Free and unlink the last region entry from the region list */
  static int region_list_remove (region_list_entry **last) {
      region_list_entry *previous = (*last)->previous;
      if (! HeapFree (GetProcessHeap (), sizeof (region_list_entry), *last))
          return FALSE;
      *last = previous;
      return TRUE;
  }
  
  #define CEIL(size,to)	(((size)+(to)-1)&~((to)-1))
  #define FLOOR(size,to)	((size)&~((to)-1))
  
  #define SBRK_SCALE  0
  /* #define SBRK_SCALE  1 */
  /* #define SBRK_SCALE  2 */
  /* #define SBRK_SCALE  4  */
  
  /* sbrk for windows */
  static void *sbrk (long size) {
      static long g_pagesize, g_my_pagesize;
      static long g_regionsize, g_my_regionsize;
      static region_list_entry *g_last;
      void *result = (void *) MORECORE_FAILURE;
  #ifdef TRACE
      printf ("sbrk %d\n", size);
  #endif
  #if defined (USE_MALLOC_LOCK) && defined (NEEDED)
      /* Wait for spin lock */
      slwait (&g_sl);
  #endif
      /* First time initialization */
      if (! g_pagesize) {
          g_pagesize = getpagesize ();
          g_my_pagesize = g_pagesize << SBRK_SCALE;
      }
      if (! g_regionsize) {
          g_regionsize = getregionsize ();
          g_my_regionsize = g_regionsize << SBRK_SCALE;
      }
      if (! g_last) {
          if (! region_list_append (&g_last, 0, 0)) 
             goto sbrk_exit;
      }
      /* Assert invariants */
      assert (g_last);
      assert ((char *) g_last->top_reserved - g_last->reserve_size <= (char *) g_last->top_allocated &&
              g_last->top_allocated <= g_last->top_committed);
      assert ((char *) g_last->top_reserved - g_last->reserve_size <= (char *) g_last->top_committed &&
              g_last->top_committed <= g_last->top_reserved &&
              (unsigned) g_last->top_committed % g_pagesize == 0);
      assert ((unsigned) g_last->top_reserved % g_regionsize == 0);
      assert ((unsigned) g_last->reserve_size % g_regionsize == 0);
      /* Allocation requested? */
      if (size >= 0) {
          /* Allocation size is the requested size */
          long allocate_size = size;
          /* Compute the size to commit */
          long to_commit = (char *) g_last->top_allocated + allocate_size - (char *) g_last->top_committed;
          /* Do we reach the commit limit? */
          if (to_commit > 0) {
              /* Round size to commit */
              long commit_size = CEIL (to_commit, g_my_pagesize);
              /* Compute the size to reserve */
              long to_reserve = (char *) g_last->top_committed + commit_size - (char *) g_last->top_reserved;
              /* Do we reach the reserve limit? */
              if (to_reserve > 0) {
                  /* Compute the remaining size to commit in the current region */
                  long remaining_commit_size = (char *) g_last->top_reserved - (char *) g_last->top_committed;
                  if (remaining_commit_size > 0) {
                      /* Assert preconditions */
                      assert ((unsigned) g_last->top_committed % g_pagesize == 0);
                      assert (0 < remaining_commit_size && remaining_commit_size % g_pagesize == 0); {
                          /* Commit this */
                          void *base_committed = VirtualAlloc (g_last->top_committed, remaining_commit_size,
  							                                 MEM_COMMIT, PAGE_READWRITE);
                          /* Check returned pointer for consistency */
                          if (base_committed != g_last->top_committed)
                              goto sbrk_exit;
                          /* Assert postconditions */
                          assert ((unsigned) base_committed % g_pagesize == 0);
  #ifdef TRACE
                          printf ("Commit %p %d\n", base_committed, remaining_commit_size);
  #endif
                          /* Adjust the regions commit top */
                          g_last->top_committed = (char *) base_committed + remaining_commit_size;
                      }
                  } {
                      /* Now we are going to search and reserve. */
                      int contiguous = -1;
                      int found = FALSE;
                      MEMORY_BASIC_INFORMATION memory_info;
                      void *base_reserved;
                      long reserve_size;
                      do {
                          /* Assume contiguous memory */
                          contiguous = TRUE;
                          /* Round size to reserve */
                          reserve_size = CEIL (to_reserve, g_my_regionsize);
                          /* Start with the current region's top */
                          memory_info.BaseAddress = g_last->top_reserved;
                          /* Assert preconditions */
                          assert ((unsigned) memory_info.BaseAddress % g_pagesize == 0);
                          assert (0 < reserve_size && reserve_size % g_regionsize == 0);
                          while (VirtualQuery (memory_info.BaseAddress, &memory_info, sizeof (memory_info))) {
                              /* Assert postconditions */
                              assert ((unsigned) memory_info.BaseAddress % g_pagesize == 0);
  #ifdef TRACE
                              printf ("Query %p %d %s\n", memory_info.BaseAddress, memory_info.RegionSize, 
                                      memory_info.State == MEM_FREE ? "FREE": 
                                      (memory_info.State == MEM_RESERVE ? "RESERVED":
                                       (memory_info.State == MEM_COMMIT ? "COMMITTED": "?")));
  #endif
                              /* Region is free, well aligned and big enough: we are done */
                              if (memory_info.State == MEM_FREE &&
                                  (unsigned) memory_info.BaseAddress % g_regionsize == 0 &&
                                  memory_info.RegionSize >= (unsigned) reserve_size) {
                                  found = TRUE;
                                  break;
                              }
                              /* From now on we can't get contiguous memory! */
                              contiguous = FALSE;
                              /* Recompute size to reserve */
                              reserve_size = CEIL (allocate_size, g_my_regionsize);
                              memory_info.BaseAddress = (char *) memory_info.BaseAddress + memory_info.RegionSize;
                              /* Assert preconditions */
                              assert ((unsigned) memory_info.BaseAddress % g_pagesize == 0);
                              assert (0 < reserve_size && reserve_size % g_regionsize == 0);
                          }
                          /* Search failed? */
                          if (! found) 
                              goto sbrk_exit;
                          /* Assert preconditions */
                          assert ((unsigned) memory_info.BaseAddress % g_regionsize == 0);
                          assert (0 < reserve_size && reserve_size % g_regionsize == 0);
                          /* Try to reserve this */
                          base_reserved = VirtualAlloc (memory_info.BaseAddress, reserve_size, 
  					                                  MEM_RESERVE, PAGE_NOACCESS);
                          if (! base_reserved) {
                              int rc = GetLastError ();
                              if (rc != ERROR_INVALID_ADDRESS) 
                                  goto sbrk_exit;
                          }
                          /* A null pointer signals (hopefully) a race condition with another thread. */
                          /* In this case, we try again. */
                      } while (! base_reserved);
                      /* Check returned pointer for consistency */
                      if (memory_info.BaseAddress && base_reserved != memory_info.BaseAddress)
                          goto sbrk_exit;
                      /* Assert postconditions */
                      assert ((unsigned) base_reserved % g_regionsize == 0);
  #ifdef TRACE
                      printf ("Reserve %p %d\n", base_reserved, reserve_size);
  #endif
                      /* Did we get contiguous memory? */
                      if (contiguous) {
                          long start_size = (char *) g_last->top_committed - (char *) g_last->top_allocated;
                          /* Adjust allocation size */
                          allocate_size -= start_size;
                          /* Adjust the regions allocation top */
                          g_last->top_allocated = g_last->top_committed;
                          /* Recompute the size to commit */
                          to_commit = (char *) g_last->top_allocated + allocate_size - (char *) g_last->top_committed;
                          /* Round size to commit */
                          commit_size = CEIL (to_commit, g_my_pagesize);
                      } 
                      /* Append the new region to the list */
                      if (! region_list_append (&g_last, base_reserved, reserve_size))
                          goto sbrk_exit;
                      /* Didn't we get contiguous memory? */
                      if (! contiguous) {
                          /* Recompute the size to commit */
                          to_commit = (char *) g_last->top_allocated + allocate_size - (char *) g_last->top_committed;
                          /* Round size to commit */
                          commit_size = CEIL (to_commit, g_my_pagesize);
                      }
                  }
              } 
              /* Assert preconditions */
              assert ((unsigned) g_last->top_committed % g_pagesize == 0);
              assert (0 < commit_size && commit_size % g_pagesize == 0); {
                  /* Commit this */
                  void *base_committed = VirtualAlloc (g_last->top_committed, commit_size, 
  				    			                     MEM_COMMIT, PAGE_READWRITE);
                  /* Check returned pointer for consistency */
                  if (base_committed != g_last->top_committed)
                      goto sbrk_exit;
                  /* Assert postconditions */
                  assert ((unsigned) base_committed % g_pagesize == 0);
  #ifdef TRACE
                  printf ("Commit %p %d\n", base_committed, commit_size);
  #endif
                  /* Adjust the regions commit top */
                  g_last->top_committed = (char *) base_committed + commit_size;
              }
          } 
          /* Adjust the regions allocation top */
          g_last->top_allocated = (char *) g_last->top_allocated + allocate_size;
          result = (char *) g_last->top_allocated - size;
      /* Deallocation requested? */
      } else if (size < 0) {
          long deallocate_size = - size;
          /* As long as we have a region to release */
          while ((char *) g_last->top_allocated - deallocate_size < (char *) g_last->top_reserved - g_last->reserve_size) {
              /* Get the size to release */
              long release_size = g_last->reserve_size;
              /* Get the base address */
              void *base_reserved = (char *) g_last->top_reserved - release_size;
              /* Assert preconditions */
              assert ((unsigned) base_reserved % g_regionsize == 0); 
              assert (0 < release_size && release_size % g_regionsize == 0); {
                  /* Release this */
                  int rc = VirtualFree (base_reserved, 0, 
                                        MEM_RELEASE);
                  /* Check returned code for consistency */
                  if (! rc)
                      goto sbrk_exit;
  #ifdef TRACE
                  printf ("Release %p %d\n", base_reserved, release_size);
  #endif
              }
              /* Adjust deallocation size */
              deallocate_size -= (char *) g_last->top_allocated - (char *) base_reserved;
              /* Remove the old region from the list */
              if (! region_list_remove (&g_last))
                  goto sbrk_exit;
          } {
              /* Compute the size to decommit */
              long to_decommit = (char *) g_last->top_committed - ((char *) g_last->top_allocated - deallocate_size);
              if (to_decommit >= g_my_pagesize) {
                  /* Compute the size to decommit */
                  long decommit_size = FLOOR (to_decommit, g_my_pagesize);
                  /*  Compute the base address */
                  void *base_committed = (char *) g_last->top_committed - decommit_size;
                  /* Assert preconditions */
                  assert ((unsigned) base_committed % g_pagesize == 0);
                  assert (0 < decommit_size && decommit_size % g_pagesize == 0); {
                      /* Decommit this */
                      int rc = VirtualFree ((char *) base_committed, decommit_size, 
                                            MEM_DECOMMIT);
                      /* Check returned code for consistency */
                      if (! rc)
                          goto sbrk_exit;
  #ifdef TRACE
                      printf ("Decommit %p %d\n", base_committed, decommit_size);
  #endif
                  }
                  /* Adjust deallocation size and regions commit and allocate top */
                  deallocate_size -= (char *) g_last->top_allocated - (char *) base_committed;
                  g_last->top_committed = base_committed;
                  g_last->top_allocated = base_committed;
              }
          }
          /* Adjust regions allocate top */
          g_last->top_allocated = (char *) g_last->top_allocated - deallocate_size;
          /* Check for underflow */
          if ((char *) g_last->top_reserved - g_last->reserve_size > (char *) g_last->top_allocated ||
              g_last->top_allocated > g_last->top_committed) {
              /* Adjust regions allocate top */
              g_last->top_allocated = (char *) g_last->top_reserved - g_last->reserve_size;
              goto sbrk_exit;
          }
          result = g_last->top_allocated;
      }
      /* Assert invariants */
      assert (g_last);
      assert ((char *) g_last->top_reserved - g_last->reserve_size <= (char *) g_last->top_allocated &&
              g_last->top_allocated <= g_last->top_committed);
      assert ((char *) g_last->top_reserved - g_last->reserve_size <= (char *) g_last->top_committed &&
              g_last->top_committed <= g_last->top_reserved &&
              (unsigned) g_last->top_committed % g_pagesize == 0);
      assert ((unsigned) g_last->top_reserved % g_regionsize == 0);
      assert ((unsigned) g_last->reserve_size % g_regionsize == 0);
  
  sbrk_exit:
  #if defined (USE_MALLOC_LOCK) && defined (NEEDED)
      /* Release spin lock */
      slrelease (&g_sl);
  #endif
      return result;
  }
  
  /* mmap for windows */
  static void *mmap (void *ptr, long size, long prot, long type, long handle, long arg) {
      static long g_pagesize;
      static long g_regionsize;
  #ifdef TRACE
      printf ("mmap %d\n", size);
  #endif
  #if defined (USE_MALLOC_LOCK) && defined (NEEDED)
      /* Wait for spin lock */
      slwait (&g_sl);
  #endif
      /* First time initialization */
      if (! g_pagesize) 
          g_pagesize = getpagesize ();
      if (! g_regionsize) 
          g_regionsize = getregionsize ();
      /* Assert preconditions */
      assert ((unsigned) ptr % g_regionsize == 0);
      assert (size % g_pagesize == 0);
      /* Allocate this */
      ptr = VirtualAlloc (ptr, size,
  					    MEM_RESERVE | MEM_COMMIT | MEM_TOP_DOWN, PAGE_READWRITE);
      if (! ptr) {
          ptr = (void *) MORECORE_FAILURE;
          goto mmap_exit;
      }
      /* Assert postconditions */
      assert ((unsigned) ptr % g_regionsize == 0);
  #ifdef TRACE
      printf ("Commit %p %d\n", ptr, size);
  #endif
  mmap_exit:
  #if defined (USE_MALLOC_LOCK) && defined (NEEDED)
      /* Release spin lock */
      slrelease (&g_sl);
  #endif
      return ptr;
  }
  
  /* munmap for windows */
  static long munmap (void *ptr, long size) {
      static long g_pagesize;
      static long g_regionsize;
      int rc = MUNMAP_FAILURE;
  #ifdef TRACE
      printf ("munmap %p %d\n", ptr, size);
  #endif
  #if defined (USE_MALLOC_LOCK) && defined (NEEDED)
      /* Wait for spin lock */
      slwait (&g_sl);
  #endif
      /* First time initialization */
      if (! g_pagesize) 
          g_pagesize = getpagesize ();
      if (! g_regionsize) 
          g_regionsize = getregionsize ();
      /* Assert preconditions */
      assert ((unsigned) ptr % g_regionsize == 0);
      assert (size % g_pagesize == 0);
      /* Free this */
      if (! VirtualFree (ptr, 0, 
                         MEM_RELEASE))
          goto munmap_exit;
      rc = 0;
  #ifdef TRACE
      printf ("Release %p %d\n", ptr, size);
  #endif
  munmap_exit:
  #if defined (USE_MALLOC_LOCK) && defined (NEEDED)
      /* Release spin lock */
      slrelease (&g_sl);
  #endif
      return rc;
  }
  
  static void vminfo (unsigned long *free, unsigned long *reserved, unsigned long *committed) {
      MEMORY_BASIC_INFORMATION memory_info;
      memory_info.BaseAddress = 0;
      *free = *reserved = *committed = 0;
      while (VirtualQuery (memory_info.BaseAddress, &memory_info, sizeof (memory_info))) {
          switch (memory_info.State) {
          case MEM_FREE:
              *free += memory_info.RegionSize;
              break;
          case MEM_RESERVE:
              *reserved += memory_info.RegionSize;
              break;
          case MEM_COMMIT:
              *committed += memory_info.RegionSize;
              break;
          }
          memory_info.BaseAddress = (char *) memory_info.BaseAddress + memory_info.RegionSize;
      }
  }
  
  static int cpuinfo (int whole, unsigned long *kernel, unsigned long *user) {
      if (whole) {
          __int64 creation64, exit64, kernel64, user64;
          int rc = GetProcessTimes (GetCurrentProcess (), 
                                    (FILETIME *) &creation64,  
                                    (FILETIME *) &exit64, 
                                    (FILETIME *) &kernel64, 
                                    (FILETIME *) &user64);
          if (! rc) {
              *kernel = 0;
              *user = 0;
              return FALSE;
          } 
          *kernel = (unsigned long) (kernel64 / 10000);
          *user = (unsigned long) (user64 / 10000);
          return TRUE;
      } else {
          __int64 creation64, exit64, kernel64, user64;
          int rc = GetThreadTimes (GetCurrentThread (), 
                                   (FILETIME *) &creation64,  
                                   (FILETIME *) &exit64, 
                                   (FILETIME *) &kernel64, 
                                   (FILETIME *) &user64);
          if (! rc) {
              *kernel = 0;
              *user = 0;
              return FALSE;
          } 
          *kernel = (unsigned long) (kernel64 / 10000);
          *user = (unsigned long) (user64 / 10000);
          return TRUE;
      }
  }
  
  #endif /* WIN32 */
  
  /* ------------------------------------------------------------
  History:
  
      V2.7.0 Sun Mar 11 14:14:06 2001  Doug Lea  (dl at gee)
        * Introduce independent_comalloc and independent_calloc.
          Thanks to Michael Pachos for motivation and help.
        * Make optional .h file available
        * Allow > 2GB requests on 32bit systems.
        * new WIN32 sbrk, mmap, munmap, lock code from <Walter@GeNeSys-e.de>.
          Thanks also to Andreas Mueller <a.mueller at paradatec.de>,
          and Anonymous.
        * Allow override of MALLOC_ALIGNMENT (Thanks to Ruud Waij for 
          helping test this.)
        * memalign: check alignment arg
        * realloc: don't try to shift chunks backwards, since this
          leads to  more fragmentation in some programs and doesn't
          seem to help in any others.
        * Collect all cases in malloc requiring system memory into sYSMALLOc
        * Use mmap as backup to sbrk
        * Place all internal state in malloc_state
        * Introduce fastbins (although similar to 2.5.1)
        * Many minor tunings and cosmetic improvements
        * Introduce USE_PUBLIC_MALLOC_WRAPPERS, USE_MALLOC_LOCK 
        * Introduce MALLOC_FAILURE_ACTION, MORECORE_CONTIGUOUS
          Thanks to Tony E. Bennett <tbennett@nvidia.com> and others.
        * Include errno.h to support default failure action.
  
      V2.6.6 Sun Dec  5 07:42:19 1999  Doug Lea  (dl at gee)
        * return null for negative arguments
        * Added Several WIN32 cleanups from Martin C. Fong <mcfong at yahoo.com>
           * Add 'LACKS_SYS_PARAM_H' for those systems without 'sys/param.h'
            (e.g. WIN32 platforms)
           * Cleanup header file inclusion for WIN32 platforms
           * Cleanup code to avoid Microsoft Visual C++ compiler complaints
           * Add 'USE_DL_PREFIX' to quickly allow co-existence with existing
             memory allocation routines
           * Set 'malloc_getpagesize' for WIN32 platforms (needs more work)
           * Use 'assert' rather than 'ASSERT' in WIN32 code to conform to
             usage of 'assert' in non-WIN32 code
           * Improve WIN32 'sbrk()' emulation's 'findRegion()' routine to
             avoid infinite loop
        * Always call 'fREe()' rather than 'free()'
  
      V2.6.5 Wed Jun 17 15:57:31 1998  Doug Lea  (dl at gee)
        * Fixed ordering problem with boundary-stamping
  
      V2.6.3 Sun May 19 08:17:58 1996  Doug Lea  (dl at gee)
        * Added pvalloc, as recommended by H.J. Liu
        * Added 64bit pointer support mainly from Wolfram Gloger
        * Added anonymously donated WIN32 sbrk emulation
        * Malloc, calloc, getpagesize: add optimizations from Raymond Nijssen
        * malloc_extend_top: fix mask error that caused wastage after
          foreign sbrks
        * Add linux mremap support code from HJ Liu
  
      V2.6.2 Tue Dec  5 06:52:55 1995  Doug Lea  (dl at gee)
        * Integrated most documentation with the code.
        * Add support for mmap, with help from
          Wolfram Gloger (Gloger@lrz.uni-muenchen.de).
        * Use last_remainder in more cases.
        * Pack bins using idea from  colin@nyx10.cs.du.edu
        * Use ordered bins instead of best-fit threshhold
        * Eliminate block-local decls to simplify tracing and debugging.
        * Support another case of realloc via move into top
        * Fix error occuring when initial sbrk_base not word-aligned.
        * Rely on page size for units instead of SBRK_UNIT to
          avoid surprises about sbrk alignment conventions.
        * Add mallinfo, mallopt. Thanks to Raymond Nijssen
          (raymond@es.ele.tue.nl) for the suggestion.
        * Add `pad' argument to malloc_trim and top_pad mallopt parameter.
        * More precautions for cases where other routines call sbrk,
          courtesy of Wolfram Gloger (Gloger@lrz.uni-muenchen.de).
        * Added macros etc., allowing use in linux libc from
          H.J. Lu (hjl@gnu.ai.mit.edu)
        * Inverted this history list
  
      V2.6.1 Sat Dec  2 14:10:57 1995  Doug Lea  (dl at gee)
        * Re-tuned and fixed to behave more nicely with V2.6.0 changes.
        * Removed all preallocation code since under current scheme
          the work required to undo bad preallocations exceeds
          the work saved in good cases for most test programs.
        * No longer use return list or unconsolidated bins since
          no scheme using them consistently outperforms those that don't
          given above changes.
        * Use best fit for very large chunks to prevent some worst-cases.
        * Added some support for debugging
  
      V2.6.0 Sat Nov  4 07:05:23 1995  Doug Lea  (dl at gee)
        * Removed footers when chunks are in use. Thanks to
          Paul Wilson (wilson@cs.texas.edu) for the suggestion.
  
      V2.5.4 Wed Nov  1 07:54:51 1995  Doug Lea  (dl at gee)
        * Added malloc_trim, with help from Wolfram Gloger
          (wmglo@Dent.MED.Uni-Muenchen.DE).
  
      V2.5.3 Tue Apr 26 10:16:01 1994  Doug Lea  (dl at g)
  
      V2.5.2 Tue Apr  5 16:20:40 1994  Doug Lea  (dl at g)
        * realloc: try to expand in both directions
        * malloc: swap order of clean-bin strategy;
        * realloc: only conditionally expand backwards
        * Try not to scavenge used bins
        * Use bin counts as a guide to preallocation
        * Occasionally bin return list chunks in first scan
        * Add a few optimizations from colin@nyx10.cs.du.edu
  
      V2.5.1 Sat Aug 14 15:40:43 1993  Doug Lea  (dl at g)
        * faster bin computation & slightly different binning
        * merged all consolidations to one part of malloc proper
           (eliminating old malloc_find_space & malloc_clean_bin)
        * Scan 2 returns chunks (not just 1)
        * Propagate failure in realloc if malloc returns 0
        * Add stuff to allow compilation on non-ANSI compilers
            from kpv@research.att.com
  
      V2.5 Sat Aug  7 07:41:59 1993  Doug Lea  (dl at g.oswego.edu)
        * removed potential for odd address access in prev_chunk
        * removed dependency on getpagesize.h
        * misc cosmetics and a bit more internal documentation
        * anticosmetics: mangled names in macros to evade debugger strangeness
        * tested on sparc, hp-700, dec-mips, rs6000
            with gcc & native cc (hp, dec only) allowing
            Detlefs & Zorn comparison study (in SIGPLAN Notices.)
  
      Trial version Fri Aug 28 13:14:29 1992  Doug Lea  (dl at g.oswego.edu)
        * Based loosely on libg++-1.2X malloc. (It retains some of the overall
           structure of old version,  but most details differ.)
  
  */
  