text: /**
   * @file
   * Dynamic pool memory manager
   *
   * lwIP has dedicated pools for many structures (netconn, protocol control blocks,
   * packet buffers, ...). All these pools are managed here.
   */
  
  /*
   * Copyright (c) 2001-2004 Swedish Institute of Computer Science.
   * All rights reserved. 
   * 
   * Redistribution and use in source and binary forms, with or without modification, 
   * are permitted provided that the following conditions are met:
   *
   * 1. Redistributions of source code must retain the above copyright notice,
   *    this list of conditions and the following disclaimer.
   * 2. Redistributions in binary form must reproduce the above copyright notice,
   *    this list of conditions and the following disclaimer in the documentation
   *    and/or other materials provided with the distribution.
   * 3. The name of the author may not be used to endorse or promote products
   *    derived from this software without specific prior written permission. 
   *
   * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR IMPLIED 
   * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF 
   * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT 
   * SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, 
   * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT 
   * OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS 
   * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN 
   * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING 
   * IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY 
   * OF SUCH DAMAGE.
   *
   * This file is part of the lwIP TCP/IP stack.
   * 
   * Author: Adam Dunkels <adam@sics.se>
   *
   */
  
  #include "lwip/opt.h"
  
  #include "lwip/memp.h"
  #include "lwip/pbuf.h"
  #include "lwip/udp.h"
  #include "lwip/raw.h"
  #include "lwip/tcp.h"
  #include "lwip/igmp.h"
  #include "lwip/api.h"
  #include "lwip/api_msg.h"
  #include "lwip/tcpip.h"
  #include "lwip/sys.h"
  #include "lwip/stats.h"
  #include "netif/etharp.h"
  #include "lwip/ip_frag.h"
  
  #include <string.h>
  
  #if !MEMP_MEM_MALLOC /* don't build if not configured for use in lwipopts.h */
  
  struct memp {
    struct memp *next;
  #if MEMP_OVERFLOW_CHECK
    const char *file;
    int line;
  #endif /* MEMP_OVERFLOW_CHECK */
  };
  
  #if MEMP_OVERFLOW_CHECK
  /* if MEMP_OVERFLOW_CHECK is turned on, we reserve some bytes at the beginning
   * and at the end of each element, initialize them as 0xcd and check
   * them later. */
  /* If MEMP_OVERFLOW_CHECK is >= 2, on every call to memp_malloc or memp_free,
   * every single element in each pool is checked!
   * This is VERY SLOW but also very helpful. */
  /* MEMP_SANITY_REGION_BEFORE and MEMP_SANITY_REGION_AFTER can be overridden in
   * lwipopts.h to change the amount reserved for checking. */
  #ifndef MEMP_SANITY_REGION_BEFORE
  #define MEMP_SANITY_REGION_BEFORE  16
  #endif /* MEMP_SANITY_REGION_BEFORE*/
  #if MEMP_SANITY_REGION_BEFORE > 0
  #define MEMP_SANITY_REGION_BEFORE_ALIGNED    LWIP_MEM_ALIGN_SIZE(MEMP_SANITY_REGION_BEFORE)
  #else
  #define MEMP_SANITY_REGION_BEFORE_ALIGNED    0
  #endif /* MEMP_SANITY_REGION_BEFORE*/
  #ifndef MEMP_SANITY_REGION_AFTER
  #define MEMP_SANITY_REGION_AFTER   16
  #endif /* MEMP_SANITY_REGION_AFTER*/
  #if MEMP_SANITY_REGION_AFTER > 0
  #define MEMP_SANITY_REGION_AFTER_ALIGNED     LWIP_MEM_ALIGN_SIZE(MEMP_SANITY_REGION_AFTER)
  #else
  #define MEMP_SANITY_REGION_AFTER_ALIGNED     0
  #endif /* MEMP_SANITY_REGION_AFTER*/
  
  /* MEMP_SIZE: save space for struct memp and for sanity check */
  #define MEMP_SIZE          (LWIP_MEM_ALIGN_SIZE(sizeof(struct memp)) + MEMP_SANITY_REGION_BEFORE_ALIGNED)
  #define MEMP_ALIGN_SIZE(x) (LWIP_MEM_ALIGN_SIZE(x) + MEMP_SANITY_REGION_AFTER_ALIGNED)
  
  #else /* MEMP_OVERFLOW_CHECK */
  
  /* No sanity checks
   * We don't need to preserve the struct memp while not allocated, so we
   * can save a little space and set MEMP_SIZE to 0.
   */
  #define MEMP_SIZE           0
  #define MEMP_ALIGN_SIZE(x) (LWIP_MEM_ALIGN_SIZE(x))
  
  #endif /* MEMP_OVERFLOW_CHECK */
  
  /** This array holds the first free element of each pool.
   *  Elements form a linked list. */
  static struct memp *memp_tab[MEMP_MAX];
  
  #else /* MEMP_MEM_MALLOC */
  
  #define MEMP_ALIGN_SIZE(x) (LWIP_MEM_ALIGN_SIZE(x))
  
  #endif /* MEMP_MEM_MALLOC */
  
  /** This array holds the element sizes of each pool. */
  #if !MEM_USE_POOLS && !MEMP_MEM_MALLOC
  static
  #endif
  const u16_t memp_sizes[MEMP_MAX] = {
  #define LWIP_MEMPOOL(name,num,size,desc)  LWIP_MEM_ALIGN_SIZE(size),
  #include "lwip/memp_std.h"
  };
  
  #if !MEMP_MEM_MALLOC /* don't build if not configured for use in lwipopts.h */
  
  /** This array holds the number of elements in each pool. */
  static const u16_t memp_num[MEMP_MAX] = {
  #define LWIP_MEMPOOL(name,num,size,desc)  (num),
  #include "lwip/memp_std.h"
  };
  
  /** This array holds a textual description of each pool. */
  #ifdef LWIP_DEBUG
  static const char *memp_desc[MEMP_MAX] = {
  #define LWIP_MEMPOOL(name,num,size,desc)  (desc),
  #include "lwip/memp_std.h"
  };
  #endif /* LWIP_DEBUG */
  
  /** This is the actual memory used by the pools. */
  static u8_t memp_memory[MEM_ALIGNMENT - 1 
  #define LWIP_MEMPOOL(name,num,size,desc) + ( (num) * (MEMP_SIZE + MEMP_ALIGN_SIZE(size) ) )
  #include "lwip/memp_std.h"
  ];
  
  #if MEMP_SANITY_CHECK
  /**
   * Check that memp-lists don't form a circle
   */
  static int
  memp_sanity(void)
  {
    s16_t i, c;
    struct memp *m, *n;
  
    for (i = 0; i < MEMP_MAX; i++) {
      for (m = memp_tab[i]; m != NULL; m = m->next) {
        c = 1;
        for (n = memp_tab[i]; n != NULL; n = n->next) {
          if (n == m && --c < 0) {
            return 0;
          }
        }
      }
    }
    return 1;
  }
  #endif /* MEMP_SANITY_CHECK*/
  #if MEMP_OVERFLOW_CHECK
  /**
   * Check if a memp element was victim of an overflow
   * (e.g. the restricted area after it has been altered)
   *
   * @param p the memp element to check
   * @param memp_size the element size of the pool p comes from
   */
  static void
  memp_overflow_check_element(struct memp *p, u16_t memp_size)
  {
    u16_t k;
    u8_t *m;
  #if MEMP_SANITY_REGION_BEFORE_ALIGNED > 0
    m = (u8_t*)p + MEMP_SIZE - MEMP_SANITY_REGION_BEFORE_ALIGNED;
    for (k = 0; k < MEMP_SANITY_REGION_BEFORE_ALIGNED; k++) {
      if (m[k] != 0xcd) {
        LWIP_ASSERT("detected memp underflow!", 0);
      }
    }
  #endif
  #if MEMP_SANITY_REGION_AFTER_ALIGNED > 0
    m = (u8_t*)p + MEMP_SIZE + memp_size;
    for (k = 0; k < MEMP_SANITY_REGION_AFTER_ALIGNED; k++) {
      if (m[k] != 0xcd) {
        LWIP_ASSERT("detected memp overflow!", 0);
      }
    }
  #endif
  }
  
  /**
   * Do an overflow check for all elements in every pool.
   *
   * @see memp_overflow_check_element for a description of the check
   */
  static void
  memp_overflow_check_all(void)
  {
    u16_t i, j;
    struct memp *p;
  
    p = LWIP_MEM_ALIGN(memp_memory);
    for (i = 0; i < MEMP_MAX; ++i) {
      p = p;
      for (j = 0; j < memp_num[i]; ++j) {
        memp_overflow_check_element(p, memp_sizes[i]);
        p = (struct memp*)((u8_t*)p + MEMP_SIZE + memp_sizes[i] + MEMP_SANITY_REGION_AFTER_ALIGNED);
      }
    }
  }
  
  /**
   * Initialize the restricted areas of all memp elements in every pool.
   */
  static void
  memp_overflow_init(void)
  {
    u16_t i, j;
    struct memp *p;
    u8_t *m;
  
    p = LWIP_MEM_ALIGN(memp_memory);
    for (i = 0; i < MEMP_MAX; ++i) {
      p = p;
      for (j = 0; j < memp_num[i]; ++j) {
  #if MEMP_SANITY_REGION_BEFORE_ALIGNED > 0
        m = (u8_t*)p + MEMP_SIZE - MEMP_SANITY_REGION_BEFORE_ALIGNED;
        memset(m, 0xcd, MEMP_SANITY_REGION_BEFORE_ALIGNED);
  #endif
  #if MEMP_SANITY_REGION_AFTER_ALIGNED > 0
        m = (u8_t*)p + MEMP_SIZE + memp_sizes[i];
        memset(m, 0xcd, MEMP_SANITY_REGION_AFTER_ALIGNED);
  #endif
        p = (struct memp*)((u8_t*)p + MEMP_SIZE + memp_sizes[i] + MEMP_SANITY_REGION_AFTER_ALIGNED);
      }
    }
  }
  #endif /* MEMP_OVERFLOW_CHECK */
  
  /**
   * Initialize this module.
   * 
   * Carves out memp_memory into linked lists for each pool-type.
   */
  void
  memp_init(void)
  {
    struct memp *memp;
    u16_t i, j;
  
    for (i = 0; i < MEMP_MAX; ++i) {
      MEMP_STATS_AVAIL(used, i, 0);
      MEMP_STATS_AVAIL(max, i, 0);
      MEMP_STATS_AVAIL(err, i, 0);
      MEMP_STATS_AVAIL(avail, i, memp_num[i]);
    }
  
    memp = LWIP_MEM_ALIGN(memp_memory);
    /* for every pool: */
    for (i = 0; i < MEMP_MAX; ++i) {
      memp_tab[i] = NULL;
      /* create a linked list of memp elements */
      for (j = 0; j < memp_num[i]; ++j) {
        memp->next = memp_tab[i];
        memp_tab[i] = memp;
        memp = (struct memp *)((u8_t *)memp + MEMP_SIZE + memp_sizes[i]
  #if MEMP_OVERFLOW_CHECK
          + MEMP_SANITY_REGION_AFTER_ALIGNED
  #endif
        );
      }
    }
  #if MEMP_OVERFLOW_CHECK
    memp_overflow_init();
    /* check everything a first time to see if it worked */
    memp_overflow_check_all();
  #endif /* MEMP_OVERFLOW_CHECK */
  }
  
  /**
   * Get an element from a specific pool.
   *
   * @param type the pool to get an element from
   *
   * the debug version has two more parameters:
   * @param file file name calling this function
   * @param line number of line where this function is called
   *
   * @return a pointer to the allocated memory or a NULL pointer on error
   */
  void *
  #if !MEMP_OVERFLOW_CHECK
  memp_malloc(memp_t type)
  #else
  memp_malloc_fn(memp_t type, const char* file, const int line)
  #endif
  {
    struct memp *memp;
    SYS_ARCH_DECL_PROTECT(old_level);
   
    LWIP_ERROR("memp_malloc: type < MEMP_MAX", (type < MEMP_MAX), return NULL;);
  
    SYS_ARCH_PROTECT(old_level);
  #if MEMP_OVERFLOW_CHECK >= 2
    memp_overflow_check_all();
  #endif /* MEMP_OVERFLOW_CHECK >= 2 */
  
    memp = memp_tab[type];
    
    if (memp != NULL) {
      memp_tab[type] = memp->next;
  #if MEMP_OVERFLOW_CHECK
      memp->next = NULL;
      memp->file = file;
      memp->line = line;
  #endif /* MEMP_OVERFLOW_CHECK */
      MEMP_STATS_INC_USED(used, type);
      LWIP_ASSERT("memp_malloc: memp properly aligned",
                  ((mem_ptr_t)memp % MEM_ALIGNMENT) == 0);
      memp = (struct memp*)((u8_t*)memp + MEMP_SIZE);
    } else {
      LWIP_DEBUGF(MEMP_DEBUG | LWIP_DBG_LEVEL_SERIOUS, ("memp_malloc: out of memory in pool %s\n", memp_desc[type]));
      MEMP_STATS_INC(err, type);
    }
  
    SYS_ARCH_UNPROTECT(old_level);
  
    return memp;
  }
  
  /**
   * Put an element back into its pool.
   *
   * @param type the pool where to put mem
   * @param mem the memp element to free
   */
  void
  memp_free(memp_t type, void *mem)
  {
    struct memp *memp;
    SYS_ARCH_DECL_PROTECT(old_level);
  
    if (mem == NULL) {
      return;
    }
    LWIP_ASSERT("memp_free: mem properly aligned",
                  ((mem_ptr_t)mem % MEM_ALIGNMENT) == 0);
  
    memp = (struct memp *)((u8_t*)mem - MEMP_SIZE);
  
    SYS_ARCH_PROTECT(old_level);
  #if MEMP_OVERFLOW_CHECK
  #if MEMP_OVERFLOW_CHECK >= 2
    memp_overflow_check_all();
  #else
    memp_overflow_check_element(memp, memp_sizes[type]);
  #endif /* MEMP_OVERFLOW_CHECK >= 2 */
  #endif /* MEMP_OVERFLOW_CHECK */
  
    MEMP_STATS_DEC(used, type); 
    
    memp->next = memp_tab[type]; 
    memp_tab[type] = memp;
  
  #if MEMP_SANITY_CHECK
    LWIP_ASSERT("memp sanity", memp_sanity());
  #endif /* MEMP_SANITY_CHECK */
  
    SYS_ARCH_UNPROTECT(old_level);
  }
  
  #endif /* MEMP_MEM_MALLOC */
  