text: // © 2016 and later: Unicode, Inc. and others.
  // License & terms of use: http://www.unicode.org/copyright.html
  /*
  ******************************************************************************
  *
  *   Copyright (C) 1997-2016, International Business Machines
  *   Corporation and others.  All Rights Reserved.
  *
  ******************************************************************************
  *
  *  FILE NAME : putilimp.h
  *
  *   Date        Name        Description
  *   10/17/04    grhoten     Move internal functions from putil.h to this file.
  ******************************************************************************
  */
  
  #ifndef PUTILIMP_H
  #define PUTILIMP_H
  
  #include "unicode/utypes.h"
  #include "unicode/putil.h"
  
  /**
   * \def U_SIGNED_RIGHT_SHIFT_IS_ARITHMETIC
   * Nearly all CPUs and compilers implement a right-shift of a signed integer
   * as an Arithmetic Shift Right which copies the sign bit (the Most Significant Bit (MSB))
   * into the vacated bits (sign extension).
   * For example, (int32_t)0xfff5fff3>>4 becomes 0xffff5fff and -1>>1=-1.
   *
   * This can be useful for storing a signed value in the upper bits
   * and another bit field in the lower bits.
   * The signed value can be retrieved by simple right-shifting.
   *
   * This is consistent with the Java language.
   *
   * However, the C standard allows compilers to implement a right-shift of a signed integer
   * as a Logical Shift Right which copies a 0 into the vacated bits.
   * For example, (int32_t)0xfff5fff3>>4 becomes 0x0fff5fff and -1>>1=0x7fffffff.
   *
   * Code that depends on the natural behavior should be guarded with this macro,
   * with an alternate path for unusual platforms.
   * @internal
   */
  #ifdef U_SIGNED_RIGHT_SHIFT_IS_ARITHMETIC
      /* Use the predefined value. */
  #else
      /*
       * Nearly all CPUs & compilers implement a right-shift of a signed integer
       * as an Arithmetic Shift Right (with sign extension).
       */
  #   define U_SIGNED_RIGHT_SHIFT_IS_ARITHMETIC 1
  #endif
  
  /** Define this to 1 if your platform supports IEEE 754 floating point,
     to 0 if it does not. */
  #ifndef IEEE_754
  #   define IEEE_754 1
  #endif
  
  /**
   * uintptr_t is an optional part of the standard definitions in stdint.h.
   * The opengroup.org documentation for stdint.h says
   * "On XSI-conformant systems, the intptr_t and uintptr_t types are required;
   * otherwise, they are optional."
   * We assume that when uintptr_t is defined, UINTPTR_MAX is defined as well.
   *
   * Do not use ptrdiff_t since it is signed. size_t is unsigned.
   */
  /* TODO: This check fails on some z environments. Filed a ticket #9357 for this. */
  #if !defined(__intptr_t_defined) && !defined(UINTPTR_MAX) && (U_PLATFORM != U_PF_OS390)
  typedef size_t uintptr_t;
  #endif
  
  /**
   * \def U_HAVE_MSVC_2003_OR_EARLIER
   * Flag for workaround of MSVC 2003 optimization bugs
   * @internal
   */
  #if !defined(U_HAVE_MSVC_2003_OR_EARLIER) && defined(_MSC_VER) && (_MSC_VER < 1400)
  #define U_HAVE_MSVC_2003_OR_EARLIER
  #endif
  
  /*===========================================================================*/
  /** @{ Information about POSIX support                                       */
  /*===========================================================================*/
  
  #ifdef U_HAVE_NL_LANGINFO_CODESET
      /* Use the predefined value. */
  #elif U_PLATFORM_USES_ONLY_WIN32_API || U_PLATFORM == U_PF_ANDROID || U_PLATFORM == U_PF_QNX
  #   define U_HAVE_NL_LANGINFO_CODESET 0
  #else
  #   define U_HAVE_NL_LANGINFO_CODESET 1
  #endif
  
  #ifdef U_NL_LANGINFO_CODESET
      /* Use the predefined value. */
  #elif !U_HAVE_NL_LANGINFO_CODESET
  #   define U_NL_LANGINFO_CODESET -1
  #elif U_PLATFORM == U_PF_OS400
     /* not defined */
  #else
  #   define U_NL_LANGINFO_CODESET CODESET
  #endif
  
  #ifdef U_TZSET
      /* Use the predefined value. */
  #elif U_PLATFORM_USES_ONLY_WIN32_API
      // UWP doesn't support tzset or environment variables for tz
  #if U_PLATFORM_HAS_WINUWP_API == 0
  #   define U_TZSET _tzset
  #endif
  #elif U_PLATFORM == U_PF_OS400
     /* not defined */
  #else
  #   define U_TZSET tzset
  #endif
  
  #if defined(U_TIMEZONE) || defined(U_HAVE_TIMEZONE)
      /* Use the predefined value. */
  #elif U_PLATFORM == U_PF_ANDROID
  #   define U_TIMEZONE timezone
  #elif U_PLATFORM_IS_LINUX_BASED
  #   if defined(__UCLIBC__)
         /* uClibc does not have __timezone or _timezone. */
  #   elif defined(_NEWLIB_VERSION)
  #      define U_TIMEZONE      _timezone
  #   elif defined(__GLIBC__)
         /* glibc */
  #      define U_TIMEZONE      __timezone
  #   endif
  #elif U_PLATFORM_USES_ONLY_WIN32_API
  #   define U_TIMEZONE _timezone
  #elif U_PLATFORM == U_PF_BSD && !defined(__NetBSD__)
     /* not defined */
  #elif U_PLATFORM == U_PF_OS400
     /* not defined */
  #elif U_PLATFORM == U_PF_IPHONE
     /* not defined */
  #else
  #   define U_TIMEZONE timezone
  #endif
  
  #ifdef U_TZNAME
      /* Use the predefined value. */
  #elif U_PLATFORM_USES_ONLY_WIN32_API
      /* not usable on all windows platforms */
  #if U_PLATFORM_HAS_WINUWP_API == 0
  #   define U_TZNAME _tzname
  #endif
  #elif U_PLATFORM == U_PF_OS400
     /* not defined */
  #else
  #   define U_TZNAME tzname
  #endif
  
  #ifdef U_HAVE_MMAP
      /* Use the predefined value. */
  #elif U_PLATFORM_USES_ONLY_WIN32_API
  #   define U_HAVE_MMAP 0
  #else
  #   define U_HAVE_MMAP 1
  #endif
  
  #ifdef U_HAVE_POPEN
      /* Use the predefined value. */
  #elif U_PLATFORM_USES_ONLY_WIN32_API
  #   define U_HAVE_POPEN 0
  #elif U_PLATFORM == U_PF_OS400
  #   define U_HAVE_POPEN 0
  #else
  #   define U_HAVE_POPEN 1
  #endif
  
  /**
   * \def U_HAVE_DIRENT_H
   * Defines whether dirent.h is available.
   * @internal
   */
  #ifdef U_HAVE_DIRENT_H
      /* Use the predefined value. */
  #elif U_PLATFORM_USES_ONLY_WIN32_API
  #   define U_HAVE_DIRENT_H 0
  #else
  #   define U_HAVE_DIRENT_H 1
  #endif
  
  /** @} */
  
  /*===========================================================================*/
  /** @{ GCC built in functions for atomic memory operations                   */
  /*===========================================================================*/
  
  /**
   * \def U_HAVE_GCC_ATOMICS
   * @internal
   */
  #ifdef U_HAVE_GCC_ATOMICS
      /* Use the predefined value. */
  #elif U_PLATFORM == U_PF_MINGW
      #define U_HAVE_GCC_ATOMICS 0
  #elif U_GCC_MAJOR_MINOR >= 404 || defined(__clang__)
      /* TODO: Intel icc and IBM xlc on AIX also support gcc atomics.  (Intel originated them.)
       *       Add them for these compilers.
       * Note: Clang sets __GNUC__ defines for version 4.2, so misses the 4.4 test here.
       */
  #   define U_HAVE_GCC_ATOMICS 1
  #else
  #   define U_HAVE_GCC_ATOMICS 0
  #endif
  
  /** @} */
  
  /**
   * \def U_HAVE_STD_ATOMICS
   * Defines whether the standard C++11 <atomic> is available.
   * ICU will use this when avialable,
   * otherwise will fall back to compiler or platform specific alternatives.
   * @internal
   */
  #ifdef U_HAVE_STD_ATOMICS
      /* Use the predefined value. */
  #elif U_CPLUSPLUS_VERSION < 11
      /* Not C++11, disable use of atomics */
  #   define U_HAVE_STD_ATOMICS 0
  #elif __clang__ && __clang_major__==3 && __clang_minor__<=1
      /* Clang 3.1, has atomic variable initializer bug. */
  #   define U_HAVE_STD_ATOMICS 0
  #else
      /* U_HAVE_ATOMIC is typically set by an autoconf test of #include <atomic>  */
      /*   Can be set manually, or left undefined, on platforms without autoconf. */
  #   if defined(U_HAVE_ATOMIC) &&  U_HAVE_ATOMIC
  #      define U_HAVE_STD_ATOMICS 1
  #   else
  #      define U_HAVE_STD_ATOMICS 0
  #   endif
  #endif
  
  
  /**
   *  \def U_HAVE_CLANG_ATOMICS
   *  Defines whether Clang c11 style built-in atomics are avaialable.
   *  These are used in preference to gcc atomics when both are available.
   */
  #ifdef U_HAVE_CLANG_ATOMICS
      /* Use the predefined value. */
  #elif __has_builtin(__c11_atomic_load) && \
      __has_builtin(__c11_atomic_store) && \
      __has_builtin(__c11_atomic_fetch_add) && \
      __has_builtin(__c11_atomic_fetch_sub)
  #    define U_HAVE_CLANG_ATOMICS 1
  #else
  #    define U_HAVE_CLANG_ATOMICS 0
  #endif
  
  /*===========================================================================*/
  /** @{ Programs used by ICU code                                             */
  /*===========================================================================*/
  
  /**
   * \def U_MAKE_IS_NMAKE
   * Defines whether the "make" program is Windows nmake.
   */
  #ifdef U_MAKE_IS_NMAKE
      /* Use the predefined value. */
  #elif U_PLATFORM == U_PF_WINDOWS
  #   define U_MAKE_IS_NMAKE 1
  #else
  #   define U_MAKE_IS_NMAKE 0
  #endif
  
  /** @} */
  
  /*==========================================================================*/
  /* Platform utilities                                                       */
  /*==========================================================================*/
  
  /**
   * Platform utilities isolates the platform dependencies of the
   * libarary.  For each platform which this code is ported to, these
   * functions may have to be re-implemented.
   */
  
  /**
   * Floating point utility to determine if a double is Not a Number (NaN).
   * @internal
   */
  U_INTERNAL UBool   U_EXPORT2 uprv_isNaN(double d);
  /**
   * Floating point utility to determine if a double has an infinite value.
   * @internal
   */
  U_INTERNAL UBool   U_EXPORT2 uprv_isInfinite(double d);
  /**
   * Floating point utility to determine if a double has a positive infinite value.
   * @internal
   */
  U_INTERNAL UBool   U_EXPORT2 uprv_isPositiveInfinity(double d);
  /**
   * Floating point utility to determine if a double has a negative infinite value.
   * @internal
   */
  U_INTERNAL UBool   U_EXPORT2 uprv_isNegativeInfinity(double d);
  /**
   * Floating point utility that returns a Not a Number (NaN) value.
   * @internal
   */
  U_INTERNAL double  U_EXPORT2 uprv_getNaN(void);
  /**
   * Floating point utility that returns an infinite value.
   * @internal
   */
  U_INTERNAL double  U_EXPORT2 uprv_getInfinity(void);
  
  /**
   * Floating point utility to truncate a double.
   * @internal
   */
  U_INTERNAL double  U_EXPORT2 uprv_trunc(double d);
  /**
   * Floating point utility to calculate the floor of a double.
   * @internal
   */
  U_INTERNAL double  U_EXPORT2 uprv_floor(double d);
  /**
   * Floating point utility to calculate the ceiling of a double.
   * @internal
   */
  U_INTERNAL double  U_EXPORT2 uprv_ceil(double d);
  /**
   * Floating point utility to calculate the absolute value of a double.
   * @internal
   */
  U_INTERNAL double  U_EXPORT2 uprv_fabs(double d);
  /**
   * Floating point utility to calculate the fractional and integer parts of a double.
   * @internal
   */
  U_INTERNAL double  U_EXPORT2 uprv_modf(double d, double* pinteger);
  /**
   * Floating point utility to calculate the remainder of a double divided by another double.
   * @internal
   */
  U_INTERNAL double  U_EXPORT2 uprv_fmod(double d, double y);
  /**
   * Floating point utility to calculate d to the power of exponent (d^exponent).
   * @internal
   */
  U_INTERNAL double  U_EXPORT2 uprv_pow(double d, double exponent);
  /**
   * Floating point utility to calculate 10 to the power of exponent (10^exponent).
   * @internal
   */
  U_INTERNAL double  U_EXPORT2 uprv_pow10(int32_t exponent);
  /**
   * Floating point utility to calculate the maximum value of two doubles.
   * @internal
   */
  U_INTERNAL double  U_EXPORT2 uprv_fmax(double d, double y);
  /**
   * Floating point utility to calculate the minimum value of two doubles.
   * @internal
   */
  U_INTERNAL double  U_EXPORT2 uprv_fmin(double d, double y);
  /**
   * Private utility to calculate the maximum value of two integers.
   * @internal
   */
  U_INTERNAL int32_t U_EXPORT2 uprv_max(int32_t d, int32_t y);
  /**
   * Private utility to calculate the minimum value of two integers.
   * @internal
   */
  U_INTERNAL int32_t U_EXPORT2 uprv_min(int32_t d, int32_t y);
  
  #if U_IS_BIG_ENDIAN
  #   define uprv_isNegative(number) (*((signed char *)&(number))<0)
  #else
  #   define uprv_isNegative(number) (*((signed char *)&(number)+sizeof(number)-1)<0)
  #endif
  
  /**
   * Return the largest positive number that can be represented by an integer
   * type of arbitrary bit length.
   * @internal
   */
  U_INTERNAL double  U_EXPORT2 uprv_maxMantissa(void);
  
  /**
   * Floating point utility to calculate the logarithm of a double.
   * @internal
   */
  U_INTERNAL double  U_EXPORT2 uprv_log(double d);
  
  /**
   * Does common notion of rounding e.g. uprv_floor(x + 0.5);
   * @param x the double number
   * @return the rounded double
   * @internal
   */
  U_INTERNAL double  U_EXPORT2 uprv_round(double x);
  
  #if 0
  /**
   * Returns the number of digits after the decimal point in a double number x.
   *
   * @param x the double number
   * @return the number of digits after the decimal point in a double number x.
   * @internal
   */
  /*U_INTERNAL int32_t  U_EXPORT2 uprv_digitsAfterDecimal(double x);*/
  #endif
  
  #if !U_CHARSET_IS_UTF8
  /**
   * Please use ucnv_getDefaultName() instead.
   * Return the default codepage for this platform and locale.
   * This function can call setlocale() on Unix platforms. Please read the
   * platform documentation on setlocale() before calling this function.
   * @return the default codepage for this platform
   * @internal
   */
  U_INTERNAL const char*  U_EXPORT2 uprv_getDefaultCodepage(void);
  #endif
  
  /**
   * Please use uloc_getDefault() instead.
   * Return the default locale ID string by querying ths system, or
   *     zero if one cannot be found.
   * This function can call setlocale() on Unix platforms. Please read the
   * platform documentation on setlocale() before calling this function.
   * @return the default locale ID string
   * @internal
   */
  U_INTERNAL const char*  U_EXPORT2 uprv_getDefaultLocaleID(void);
  
  /**
   * Time zone utilities
   *
   * Wrappers for C runtime library functions relating to timezones.
   * The t_tzset() function (similar to tzset) uses the current setting
   * of the environment variable TZ to assign values to three global
   * variables: daylight, timezone, and tzname. These variables have the
   * following meanings, and are declared in &lt;time.h&gt;.
   *
   *   daylight   Nonzero if daylight-saving-time zone (DST) is specified
   *              in TZ; otherwise, 0. Default value is 1.
   *   timezone   Difference in seconds between coordinated universal
   *              time and local time. E.g., -28,800 for PST (GMT-8hrs)
   *   tzname(0)  Three-letter time-zone name derived from TZ environment
   *              variable. E.g., "PST".
   *   tzname(1)  Three-letter DST zone name derived from TZ environment
   *              variable.  E.g., "PDT". If DST zone is omitted from TZ,
   *              tzname(1) is an empty string.
   *
   * Notes: For example, to set the TZ environment variable to correspond
   * to the current time zone in Germany, you can use one of the
   * following statements:
   *
   *   set TZ=GST1GDT
   *   set TZ=GST+1GDT
   *
   * If the TZ value is not set, t_tzset() attempts to use the time zone
   * information specified by the operating system. Under Windows NT
   * and Windows 95, this information is specified in the Control Panel's
   * Date/Time application.
   * @internal
   */
  U_INTERNAL void     U_EXPORT2 uprv_tzset(void);
  
  /**
   * Difference in seconds between coordinated universal
   * time and local time. E.g., -28,800 for PST (GMT-8hrs)
   * @return the difference in seconds between coordinated universal time and local time.
   * @internal
   */
  U_INTERNAL int32_t  U_EXPORT2 uprv_timezone(void);
  
  /**
   *   tzname(0)  Three-letter time-zone name derived from TZ environment
   *              variable. E.g., "PST".
   *   tzname(1)  Three-letter DST zone name derived from TZ environment
   *              variable.  E.g., "PDT". If DST zone is omitted from TZ,
   *              tzname(1) is an empty string.
   * @internal
   */
  U_INTERNAL const char* U_EXPORT2 uprv_tzname(int n);
  
  /**
   * Reset the global tzname cache.
   * @internal
   */
  U_INTERNAL void uprv_tzname_clear_cache();
  
  /**
   * Get UTC (GMT) time measured in milliseconds since 0:00 on 1/1/1970.
   * This function is affected by 'faketime' and should be the bottleneck for all user-visible ICU time functions.
   * @return the UTC time measured in milliseconds
   * @internal
   */
  U_INTERNAL UDate U_EXPORT2 uprv_getUTCtime(void);
  
  /**
   * Get UTC (GMT) time measured in milliseconds since 0:00 on 1/1/1970.
   * This function is not affected by 'faketime', so it should only be used by low level test functions- not by anything that
   * exposes time to the end user.
   * @return the UTC time measured in milliseconds
   * @internal
   */
  U_INTERNAL UDate U_EXPORT2 uprv_getRawUTCtime(void);
  
  /**
   * Determine whether a pathname is absolute or not, as defined by the platform.
   * @param path Pathname to test
   * @return TRUE if the path is absolute
   * @internal (ICU 3.0)
   */
  U_INTERNAL UBool U_EXPORT2 uprv_pathIsAbsolute(const char *path);
  
  /**
   * Use U_MAX_PTR instead of this function.
   * @param void pointer to test
   * @return the largest possible pointer greater than the base
   * @internal (ICU 3.8)
   */
  U_INTERNAL void * U_EXPORT2 uprv_maximumPtr(void *base);
  
  /**
   * Maximum value of a (void*) - use to indicate the limit of an 'infinite' buffer.
   * In fact, buffer sizes must not exceed 2GB so that the difference between
   * the buffer limit and the buffer start can be expressed in an int32_t.
   *
   * The definition of U_MAX_PTR must fulfill the following conditions:
   * - return the largest possible pointer greater than base
   * - return a valid pointer according to the machine architecture (AS/400, 64-bit, etc.)
   * - avoid wrapping around at high addresses
   * - make sure that the returned pointer is not farther from base than 0x7fffffff bytes
   *
   * @param base The beginning of a buffer to find the maximum offset from
   * @internal
   */
  #ifndef U_MAX_PTR
  #  if U_PLATFORM == U_PF_OS390 && !defined(_LP64)
      /* We have 31-bit pointers. */
  #    define U_MAX_PTR(base) ((void *)0x7fffffff)
  #  elif U_PLATFORM == U_PF_OS400
  #    define U_MAX_PTR(base) uprv_maximumPtr((void *)base)
  #  elif 0
      /*
       * For platforms where pointers are scalar values (which is normal, but unlike i5/OS)
       * but that do not define uintptr_t.
       *
       * However, this does not work on modern compilers:
       * The C++ standard does not define pointer overflow, and allows compilers to
       * assume that p+u>p for any pointer p and any integer u>0.
       * Thus, modern compilers optimize away the ">" comparison.
       * (See ICU tickets #7187 and #8096.)
       */
  #    define U_MAX_PTR(base) \
      ((void *)(((char *)(base)+0x7fffffffu) > (char *)(base) \
          ? ((char *)(base)+0x7fffffffu) \
          : (char *)-1))
  #  else
      /* Default version. C++ standard compliant for scalar pointers. */
  #    define U_MAX_PTR(base) \
      ((void *)(((uintptr_t)(base)+0x7fffffffu) > (uintptr_t)(base) \
          ? ((uintptr_t)(base)+0x7fffffffu) \
          : (uintptr_t)-1))
  #  endif
  #endif
  
  /*  Dynamic Library Functions */
  
  typedef void (UVoidFunction)(void);
  
  #if U_ENABLE_DYLOAD
  /**
   * Load a library
   * @internal (ICU 4.4)
   */
  U_INTERNAL void * U_EXPORT2 uprv_dl_open(const char *libName, UErrorCode *status);
  
  /**
   * Close a library
   * @internal (ICU 4.4)
   */
  U_INTERNAL void U_EXPORT2 uprv_dl_close( void *lib, UErrorCode *status);
  
  /**
   * Extract a symbol from a library (function)
   * @internal (ICU 4.8)
   */
  U_INTERNAL UVoidFunction* U_EXPORT2 uprv_dlsym_func( void *lib, const char *symbolName, UErrorCode *status);
  
  /**
   * Extract a symbol from a library (function)
   * Not implemented, no clients.
   * @internal
   */
  /* U_INTERNAL void * U_EXPORT2 uprv_dlsym_data( void *lib, const char *symbolName, UErrorCode *status); */
  
  #endif
  
  /**
   * Define malloc and related functions
   * @internal
   */
  #if U_PLATFORM == U_PF_OS400
  # define uprv_default_malloc(x) _C_TS_malloc(x)
  # define uprv_default_realloc(x,y) _C_TS_realloc(x,y)
  # define uprv_default_free(x) _C_TS_free(x)
  /* also _C_TS_calloc(x) */
  #else
  /* C defaults */
  # define uprv_default_malloc(x) malloc(x)
  # define uprv_default_realloc(x,y) realloc(x,y)
  # define uprv_default_free(x) free(x)
  #endif
  
  
  #endif
  