Diff: lwip/core/mem.c

Revision:

1:9d93f4dc2f46

Parent:

0:8b387bed54c2

--- a/lwip/core/mem.c	Mon Jan 10 21:03:11 2011 +0000
+++ /dev/null	Thu Jan 01 00:00:00 1970 +0000
@@ -1,643 +0,0 @@
-#pragma diag_remark 177
-/**
- * @file
- * Dynamic memory manager
- *
- * This is a lightweight replacement for the standard C library malloc().
- *
- * If you want to use the standard C library malloc() instead, define
- * MEM_LIBC_MALLOC to 1 in your lwipopts.h
- *
- * To let mem_malloc() use pools (prevents fragmentation and is much faster than
- * a heap but might waste some memory), define MEM_USE_POOLS to 1, define
- * MEM_USE_CUSTOM_POOLS to 1 and create a file "lwippools.h" that includes a list
- * of pools like this (more pools can be added between _START and _END):
- *
- * Define three pools with sizes 256, 512, and 1512 bytes
- * LWIP_MALLOC_MEMPOOL_START
- * LWIP_MALLOC_MEMPOOL(20, 256)
- * LWIP_MALLOC_MEMPOOL(10, 512)
- * LWIP_MALLOC_MEMPOOL(5, 1512)
- * LWIP_MALLOC_MEMPOOL_END
- */
-
-/*
- * 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>
- *         Simon Goldschmidt
- *
- */
-
-#include "lwip/opt.h"
-
-#if !MEM_LIBC_MALLOC /* don't build if not configured for use in lwipopts.h */
-
-#include "lwip/def.h"
-#include "lwip/mem.h"
-#include "lwip/sys.h"
-#include "lwip/stats.h"
-#include "lwip/err.h"
-
-#include <string.h>
-
-#if MEM_USE_POOLS
-/* lwIP head implemented with different sized pools */
-
-/**
- * Allocate memory: determine the smallest pool that is big enough
- * to contain an element of 'size' and get an element from that pool.
- *
- * @param size the size in bytes of the memory needed
- * @return a pointer to the allocated memory or NULL if the pool is empty
- */
-void *
-mem_malloc(mem_size_t size)
-{
-  struct memp_malloc_helper *element;
-  memp_t poolnr;
-  mem_size_t required_size = size + sizeof(struct memp_malloc_helper);
-
-  for (poolnr = MEMP_POOL_FIRST; poolnr <= MEMP_POOL_LAST; poolnr = (memp_t)(poolnr + 1)) {
-#if MEM_USE_POOLS_TRY_BIGGER_POOL
-again:
-#endif /* MEM_USE_POOLS_TRY_BIGGER_POOL */
-    /* is this pool big enough to hold an element of the required size
-       plus a struct memp_malloc_helper that saves the pool this element came from? */
-    if (required_size <= memp_sizes[poolnr]) {
-      break;
-    }
-  }
-  if (poolnr > MEMP_POOL_LAST) {
-    LWIP_ASSERT("mem_malloc(): no pool is that big!", 0);
-    return NULL;
-  }
-  element = (struct memp_malloc_helper*)memp_malloc(poolnr);
-  if (element == NULL) {
-    /* No need to DEBUGF or ASSERT: This error is already
-       taken care of in memp.c */
-#if MEM_USE_POOLS_TRY_BIGGER_POOL
-    /** Try a bigger pool if this one is empty! */
-    if (poolnr < MEMP_POOL_LAST) {
-      poolnr++;
-      goto again;
-    }
-#endif /* MEM_USE_POOLS_TRY_BIGGER_POOL */
-    return NULL;
-  }
-
-  /* save the pool number this element came from */
-  element->poolnr = poolnr;
-  /* and return a pointer to the memory directly after the struct memp_malloc_helper */
-  element++;
-
-  return element;
-}
-
-/**
- * Free memory previously allocated by mem_malloc. Loads the pool number
- * and calls memp_free with that pool number to put the element back into
- * its pool
- *
- * @param rmem the memory element to free
- */
-void
-mem_free(void *rmem)
-{
-  struct memp_malloc_helper *hmem = (struct memp_malloc_helper*)rmem;
-
-  LWIP_ASSERT("rmem != NULL", (rmem != NULL));
-  LWIP_ASSERT("rmem == MEM_ALIGN(rmem)", (rmem == LWIP_MEM_ALIGN(rmem)));
-
-  /* get the original struct memp_malloc_helper */
-  hmem--;
-
-  LWIP_ASSERT("hmem != NULL", (hmem != NULL));
-  LWIP_ASSERT("hmem == MEM_ALIGN(hmem)", (hmem == LWIP_MEM_ALIGN(hmem)));
-  LWIP_ASSERT("hmem->poolnr < MEMP_MAX", (hmem->poolnr < MEMP_MAX));
-
-  /* and put it in the pool we saved earlier */
-  memp_free(hmem->poolnr, hmem);
-}
-
-#else /* MEM_USE_POOLS */
-/* lwIP replacement for your libc malloc() */
-
-/**
- * The heap is made up as a list of structs of this type.
- * This does not have to be aligned since for getting its size,
- * we only use the macro SIZEOF_STRUCT_MEM, which automatically alignes.
- */
-struct mem {
-  /** index (-> ram[next]) of the next struct */
-  mem_size_t next;
-  /** index (-> ram[prev]) of the previous struct */
-  mem_size_t prev;
-  /** 1: this area is used; 0: this area is unused */
-  u8_t used;
-};
-
-/** All allocated blocks will be MIN_SIZE bytes big, at least!
- * MIN_SIZE can be overridden to suit your needs. Smaller values save space,
- * larger values could prevent too small blocks to fragment the RAM too much. */
-#ifndef MIN_SIZE
-#define MIN_SIZE             12
-#endif /* MIN_SIZE */
-/* some alignment macros: we define them here for better source code layout */
-#define MIN_SIZE_ALIGNED     LWIP_MEM_ALIGN_SIZE(MIN_SIZE)
-#define SIZEOF_STRUCT_MEM    LWIP_MEM_ALIGN_SIZE(sizeof(struct mem))
-#define MEM_SIZE_ALIGNED     LWIP_MEM_ALIGN_SIZE(MEM_SIZE)
-
-/** If you want to relocate the heap to external memory, simply define
- * LWIP_RAM_HEAP_POINTER as a void-pointer to that location.
- * If so, make sure the memory at that location is big enough (see below on
- * how that space is calculated). */
-#ifndef LWIP_RAM_HEAP_POINTER
-/** the heap. we need one struct mem at the end and some room for alignment */
-u8_t ram_heap[MEM_SIZE_ALIGNED + (2*SIZEOF_STRUCT_MEM) + MEM_ALIGNMENT] MEM_POSITION;
-#define LWIP_RAM_HEAP_POINTER ram_heap
-#endif /* LWIP_RAM_HEAP_POINTER */
-
-/** pointer to the heap (ram_heap): for alignment, ram is now a pointer instead of an array */
-static u8_t *ram;
-/** the last entry, always unused! */
-static struct mem *ram_end;
-/** pointer to the lowest free block, this is used for faster search */
-static struct mem *lfree;
-
-/** concurrent access protection */
-static sys_mutex_t mem_mutex;
-
-#if LWIP_ALLOW_MEM_FREE_FROM_OTHER_CONTEXT
-
-static volatile u8_t mem_free_count;
-
-/* Allow mem_free from other (e.g. interrupt) context */
-#define LWIP_MEM_FREE_DECL_PROTECT()  SYS_ARCH_DECL_PROTECT(lev_free)
-#define LWIP_MEM_FREE_PROTECT()       SYS_ARCH_PROTECT(lev_free)
-#define LWIP_MEM_FREE_UNPROTECT()     SYS_ARCH_UNPROTECT(lev_free)
-#define LWIP_MEM_ALLOC_DECL_PROTECT() SYS_ARCH_DECL_PROTECT(lev_alloc)
-#define LWIP_MEM_ALLOC_PROTECT()      SYS_ARCH_PROTECT(lev_alloc)
-#define LWIP_MEM_ALLOC_UNPROTECT()    SYS_ARCH_UNPROTECT(lev_alloc)
-
-#else /* LWIP_ALLOW_MEM_FREE_FROM_OTHER_CONTEXT */
-
-/* Protect the heap only by using a semaphore */
-#define LWIP_MEM_FREE_DECL_PROTECT()
-#define LWIP_MEM_FREE_PROTECT()    sys_mutex_lock(&mem_mutex)
-#define LWIP_MEM_FREE_UNPROTECT()  sys_mutex_unlock(&mem_mutex)
-/* mem_malloc is protected using semaphore AND LWIP_MEM_ALLOC_PROTECT */
-#define LWIP_MEM_ALLOC_DECL_PROTECT()
-#define LWIP_MEM_ALLOC_PROTECT()
-#define LWIP_MEM_ALLOC_UNPROTECT()
-
-#endif /* LWIP_ALLOW_MEM_FREE_FROM_OTHER_CONTEXT */
-
-
-/**
- * "Plug holes" by combining adjacent empty struct mems.
- * After this function is through, there should not exist
- * one empty struct mem pointing to another empty struct mem.
- *
- * @param mem this points to a struct mem which just has been freed
- * @internal this function is only called by mem_free() and mem_trim()
- *
- * This assumes access to the heap is protected by the calling function
- * already.
- */
-static void
-plug_holes(struct mem *mem)
-{
-  struct mem *nmem;
-  struct mem *pmem;
-
-  LWIP_ASSERT("plug_holes: mem >= ram", (u8_t *)mem >= ram);
-  LWIP_ASSERT("plug_holes: mem < ram_end", (u8_t *)mem < (u8_t *)ram_end);
-  LWIP_ASSERT("plug_holes: mem->used == 0", mem->used == 0);
-
-  /* plug hole forward */
-  LWIP_ASSERT("plug_holes: mem->next <= MEM_SIZE_ALIGNED", mem->next <= MEM_SIZE_ALIGNED);
-
-  nmem = (struct mem *)(void *)&ram[mem->next];
-  if (mem != nmem && nmem->used == 0 && (u8_t *)nmem != (u8_t *)ram_end) {
-    /* if mem->next is unused and not end of ram, combine mem and mem->next */
-    if (lfree == nmem) {
-      lfree = mem;
-    }
-    mem->next = nmem->next;
-    ((struct mem *)(void *)&ram[nmem->next])->prev = (mem_size_t)((u8_t *)mem - ram);
-  }
-
-  /* plug hole backward */
-  pmem = (struct mem *)(void *)&ram[mem->prev];
-  if (pmem != mem && pmem->used == 0) {
-    /* if mem->prev is unused, combine mem and mem->prev */
-    if (lfree == mem) {
-      lfree = pmem;
-    }
-    pmem->next = mem->next;
-    ((struct mem *)(void *)&ram[mem->next])->prev = (mem_size_t)((u8_t *)pmem - ram);
-  }
-}
-
-/**
- * Zero the heap and initialize start, end and lowest-free
- */
-void
-mem_init(void)
-{
-  struct mem *mem;
-
-  LWIP_ASSERT("Sanity check alignment",
-    (SIZEOF_STRUCT_MEM & (MEM_ALIGNMENT-1)) == 0);
-
-  /* align the heap */
-  ram = (u8_t *)LWIP_MEM_ALIGN(LWIP_RAM_HEAP_POINTER);
-  /* initialize the start of the heap */
-  mem = (struct mem *)(void *)ram;
-  mem->next = MEM_SIZE_ALIGNED;
-  mem->prev = 0;
-  mem->used = 0;
-  /* initialize the end of the heap */
-  ram_end = (struct mem *)(void *)&ram[MEM_SIZE_ALIGNED];
-  ram_end->used = 1;
-  ram_end->next = MEM_SIZE_ALIGNED;
-  ram_end->prev = MEM_SIZE_ALIGNED;
-
-  /* initialize the lowest-free pointer to the start of the heap */
-  lfree = (struct mem *)(void *)ram;
-
-  MEM_STATS_AVAIL(avail, MEM_SIZE_ALIGNED);
-
-  if(sys_mutex_new(&mem_mutex) != ERR_OK) {
-    LWIP_ASSERT("failed to create mem_mutex", 0);
-  }
-}
-
-/**
- * Put a struct mem back on the heap
- *
- * @param rmem is the data portion of a struct mem as returned by a previous
- *             call to mem_malloc()
- */
-void
-mem_free(void *rmem)
-{
-  struct mem *mem;
-  LWIP_MEM_FREE_DECL_PROTECT();
-
-  if (rmem == NULL) {
-    LWIP_DEBUGF(MEM_DEBUG | LWIP_DBG_TRACE | LWIP_DBG_LEVEL_SERIOUS, ("mem_free(p == NULL) was called.\n"));
-    return;
-  }
-  LWIP_ASSERT("mem_free: sanity check alignment", (((mem_ptr_t)rmem) & (MEM_ALIGNMENT-1)) == 0);
-
-  LWIP_ASSERT("mem_free: legal memory", (u8_t *)rmem >= (u8_t *)ram &&
-    (u8_t *)rmem < (u8_t *)ram_end);
-
-  if ((u8_t *)rmem < (u8_t *)ram || (u8_t *)rmem >= (u8_t *)ram_end) {
-    SYS_ARCH_DECL_PROTECT(lev);
-    LWIP_DEBUGF(MEM_DEBUG | LWIP_DBG_LEVEL_SEVERE, ("mem_free: illegal memory\n"));
-    /* protect mem stats from concurrent access */
-    SYS_ARCH_PROTECT(lev);
-    MEM_STATS_INC(illegal);
-    SYS_ARCH_UNPROTECT(lev);
-    return;
-  }
-  /* protect the heap from concurrent access */
-  LWIP_MEM_FREE_PROTECT();
-  /* Get the corresponding struct mem ... */
-  mem = (struct mem *)(void *)((u8_t *)rmem - SIZEOF_STRUCT_MEM);
-  /* ... which has to be in a used state ... */
-  LWIP_ASSERT("mem_free: mem->used", mem->used);
-  /* ... and is now unused. */
-  mem->used = 0;
-
-  if (mem < lfree) {
-    /* the newly freed struct is now the lowest */
-    lfree = mem;
-  }
-
-  MEM_STATS_DEC_USED(used, mem->next - (mem_size_t)(((u8_t *)mem - ram)));
-
-  /* finally, see if prev or next are free also */
-  plug_holes(mem);
-#if LWIP_ALLOW_MEM_FREE_FROM_OTHER_CONTEXT
-  mem_free_count = 1;
-#endif /* LWIP_ALLOW_MEM_FREE_FROM_OTHER_CONTEXT */
-  LWIP_MEM_FREE_UNPROTECT();
-}
-
-/**
- * Shrink memory returned by mem_malloc().
- *
- * @param rmem pointer to memory allocated by mem_malloc the is to be shrinked
- * @param newsize required size after shrinking (needs to be smaller than or
- *                equal to the previous size)
- * @return for compatibility reasons: is always == rmem, at the moment
- *         or NULL if newsize is > old size, in which case rmem is NOT touched
- *         or freed!
- */
-void *
-mem_trim(void *rmem, mem_size_t newsize)
-{
-  mem_size_t size;
-  mem_size_t ptr, ptr2;
-  struct mem *mem, *mem2;
-  /* use the FREE_PROTECT here: it protects with sem OR SYS_ARCH_PROTECT */
-  LWIP_MEM_FREE_DECL_PROTECT();
-
-  /* Expand the size of the allocated memory region so that we can
-     adjust for alignment. */
-  newsize = LWIP_MEM_ALIGN_SIZE(newsize);
-
-  if(newsize < MIN_SIZE_ALIGNED) {
-    /* every data block must be at least MIN_SIZE_ALIGNED long */
-    newsize = MIN_SIZE_ALIGNED;
-  }
-
-  if (newsize > MEM_SIZE_ALIGNED) {
-    return NULL;
-  }
-
-  LWIP_ASSERT("mem_trim: legal memory", (u8_t *)rmem >= (u8_t *)ram &&
-   (u8_t *)rmem < (u8_t *)ram_end);
-
-  if ((u8_t *)rmem < (u8_t *)ram || (u8_t *)rmem >= (u8_t *)ram_end) {
-    SYS_ARCH_DECL_PROTECT(lev);
-    LWIP_DEBUGF(MEM_DEBUG | LWIP_DBG_LEVEL_SEVERE, ("mem_trim: illegal memory\n"));
-    /* protect mem stats from concurrent access */
-    SYS_ARCH_PROTECT(lev);
-    MEM_STATS_INC(illegal);
-    SYS_ARCH_UNPROTECT(lev);
-    return rmem;
-  }
-  /* Get the corresponding struct mem ... */
-  mem = (struct mem *)(void *)((u8_t *)rmem - SIZEOF_STRUCT_MEM);
-  /* ... and its offset pointer */
-  ptr = (mem_size_t)((u8_t *)mem - ram);
-
-  size = mem->next - ptr - SIZEOF_STRUCT_MEM;
-  LWIP_ASSERT("mem_trim can only shrink memory", newsize <= size);
-  if (newsize > size) {
-    /* not supported */
-    return NULL;
-  }
-  if (newsize == size) {
-    /* No change in size, simply return */
-    return rmem;
-  }
-
-  /* protect the heap from concurrent access */
-  LWIP_MEM_FREE_PROTECT();
-
-  mem2 = (struct mem *)(void *)&ram[mem->next];
-  if(mem2->used == 0) {
-    /* The next struct is unused, we can simply move it at little */
-    mem_size_t next;
-    /* remember the old next pointer */
-    next = mem2->next;
-    /* create new struct mem which is moved directly after the shrinked mem */
-    ptr2 = ptr + SIZEOF_STRUCT_MEM + newsize;
-    if (lfree == mem2) {
-      lfree = (struct mem *)(void *)&ram[ptr2];
-    }
-    mem2 = (struct mem *)(void *)&ram[ptr2];
-    mem2->used = 0;
-    /* restore the next pointer */
-    mem2->next = next;
-    /* link it back to mem */
-    mem2->prev = ptr;
-    /* link mem to it */
-    mem->next = ptr2;
-    /* last thing to restore linked list: as we have moved mem2,
-     * let 'mem2->next->prev' point to mem2 again. but only if mem2->next is not
-     * the end of the heap */
-    if (mem2->next != MEM_SIZE_ALIGNED) {
-      ((struct mem *)(void *)&ram[mem2->next])->prev = ptr2;
-    }
-    MEM_STATS_DEC_USED(used, (size - newsize));
-    /* no need to plug holes, we've already done that */
-  } else if (newsize + SIZEOF_STRUCT_MEM + MIN_SIZE_ALIGNED <= size) {
-    /* Next struct is used but there's room for another struct mem with
-     * at least MIN_SIZE_ALIGNED of data.
-     * Old size ('size') must be big enough to contain at least 'newsize' plus a struct mem
-     * ('SIZEOF_STRUCT_MEM') with some data ('MIN_SIZE_ALIGNED').
-     * @todo we could leave out MIN_SIZE_ALIGNED. We would create an empty
-     *       region that couldn't hold data, but when mem->next gets freed,
-     *       the 2 regions would be combined, resulting in more free memory */
-    ptr2 = ptr + SIZEOF_STRUCT_MEM + newsize;
-    mem2 = (struct mem *)(void *)&ram[ptr2];
-    if (mem2 < lfree) {
-      lfree = mem2;
-    }
-    mem2->used = 0;
-    mem2->next = mem->next;
-    mem2->prev = ptr;
-    mem->next = ptr2;
-    if (mem2->next != MEM_SIZE_ALIGNED) {
-      ((struct mem *)(void *)&ram[mem2->next])->prev = ptr2;
-    }
-    MEM_STATS_DEC_USED(used, (size - newsize));
-    /* the original mem->next is used, so no need to plug holes! */
-  }
-  /* else {
-    next struct mem is used but size between mem and mem2 is not big enough
-    to create another struct mem
-    -> don't do anyhting. 
-    -> the remaining space stays unused since it is too small
-  } */
-#if LWIP_ALLOW_MEM_FREE_FROM_OTHER_CONTEXT
-  mem_free_count = 1;
-#endif /* LWIP_ALLOW_MEM_FREE_FROM_OTHER_CONTEXT */
-  LWIP_MEM_FREE_UNPROTECT();
-  return rmem;
-}
-
-/**
- * Adam's mem_malloc() plus solution for bug #17922
- * Allocate a block of memory with a minimum of 'size' bytes.
- *
- * @param size is the minimum size of the requested block in bytes.
- * @return pointer to allocated memory or NULL if no free memory was found.
- *
- * Note that the returned value will always be aligned (as defined by MEM_ALIGNMENT).
- */
-void *
-mem_malloc(mem_size_t size)
-{
-  mem_size_t ptr, ptr2;
-  struct mem *mem, *mem2;
-#if LWIP_ALLOW_MEM_FREE_FROM_OTHER_CONTEXT
-  u8_t local_mem_free_count = 0;
-#endif /* LWIP_ALLOW_MEM_FREE_FROM_OTHER_CONTEXT */
-  LWIP_MEM_ALLOC_DECL_PROTECT();
-
-  if (size == 0) {
-    return NULL;
-  }
-
-  /* Expand the size of the allocated memory region so that we can
-     adjust for alignment. */
-  size = LWIP_MEM_ALIGN_SIZE(size);
-
-  if(size < MIN_SIZE_ALIGNED) {
-    /* every data block must be at least MIN_SIZE_ALIGNED long */
-    size = MIN_SIZE_ALIGNED;
-  }
-
-  if (size > MEM_SIZE_ALIGNED) {
-    return NULL;
-  }
-
-  /* protect the heap from concurrent access */
-  sys_mutex_lock(&mem_mutex);
-  LWIP_MEM_ALLOC_PROTECT();
-#if LWIP_ALLOW_MEM_FREE_FROM_OTHER_CONTEXT
-  /* run as long as a mem_free disturbed mem_malloc */
-  do {
-    local_mem_free_count = 0;
-#endif /* LWIP_ALLOW_MEM_FREE_FROM_OTHER_CONTEXT */
-
-    /* Scan through the heap searching for a free block that is big enough,
-     * beginning with the lowest free block.
-     */
-    for (ptr = (mem_size_t)((u8_t *)lfree - ram); ptr < MEM_SIZE_ALIGNED - size;
-         ptr = ((struct mem *)(void *)&ram[ptr])->next) {
-      mem = (struct mem *)(void *)&ram[ptr];
-#if LWIP_ALLOW_MEM_FREE_FROM_OTHER_CONTEXT
-      mem_free_count = 0;
-      LWIP_MEM_ALLOC_UNPROTECT();
-      /* allow mem_free to run */
-      LWIP_MEM_ALLOC_PROTECT();
-      if (mem_free_count != 0) {
-        local_mem_free_count = mem_free_count;
-      }
-      mem_free_count = 0;
-#endif /* LWIP_ALLOW_MEM_FREE_FROM_OTHER_CONTEXT */
-
-      if ((!mem->used) &&
-          (mem->next - (ptr + SIZEOF_STRUCT_MEM)) >= size) {
-        /* mem is not used and at least perfect fit is possible:
-         * mem->next - (ptr + SIZEOF_STRUCT_MEM) gives us the 'user data size' of mem */
-
-        if (mem->next - (ptr + SIZEOF_STRUCT_MEM) >= (size + SIZEOF_STRUCT_MEM + MIN_SIZE_ALIGNED)) {
-          /* (in addition to the above, we test if another struct mem (SIZEOF_STRUCT_MEM) containing
-           * at least MIN_SIZE_ALIGNED of data also fits in the 'user data space' of 'mem')
-           * -> split large block, create empty remainder,
-           * remainder must be large enough to contain MIN_SIZE_ALIGNED data: if
-           * mem->next - (ptr + (2*SIZEOF_STRUCT_MEM)) == size,
-           * struct mem would fit in but no data between mem2 and mem2->next
-           * @todo we could leave out MIN_SIZE_ALIGNED. We would create an empty
-           *       region that couldn't hold data, but when mem->next gets freed,
-           *       the 2 regions would be combined, resulting in more free memory
-           */
-          ptr2 = ptr + SIZEOF_STRUCT_MEM + size;
-          /* create mem2 struct */
-          mem2 = (struct mem *)(void *)&ram[ptr2];
-          mem2->used = 0;
-          mem2->next = mem->next;
-          mem2->prev = ptr;
-          /* and insert it between mem and mem->next */
-          mem->next = ptr2;
-          mem->used = 1;
-
-          if (mem2->next != MEM_SIZE_ALIGNED) {
-            ((struct mem *)(void *)&ram[mem2->next])->prev = ptr2;
-          }
-          MEM_STATS_INC_USED(used, (size + SIZEOF_STRUCT_MEM));
-        } else {
-          /* (a mem2 struct does no fit into the user data space of mem and mem->next will always
-           * be used at this point: if not we have 2 unused structs in a row, plug_holes should have
-           * take care of this).
-           * -> near fit or excact fit: do not split, no mem2 creation
-           * also can't move mem->next directly behind mem, since mem->next
-           * will always be used at this point!
-           */
-          mem->used = 1;
-          MEM_STATS_INC_USED(used, mem->next - (mem_size_t)((u8_t *)mem - ram));
-        }
-
-        if (mem == lfree) {
-          /* Find next free block after mem and update lowest free pointer */
-          while (lfree->used && lfree != ram_end) {
-            LWIP_MEM_ALLOC_UNPROTECT();
-            /* prevent high interrupt latency... */
-            LWIP_MEM_ALLOC_PROTECT();
-            lfree = (struct mem *)(void *)&ram[lfree->next];
-          }
-          LWIP_ASSERT("mem_malloc: !lfree->used", ((lfree == ram_end) || (!lfree->used)));
-        }
-        LWIP_MEM_ALLOC_UNPROTECT();
-        sys_mutex_unlock(&mem_mutex);
-        LWIP_ASSERT("mem_malloc: allocated memory not above ram_end.",
-         (mem_ptr_t)mem + SIZEOF_STRUCT_MEM + size <= (mem_ptr_t)ram_end);
-        LWIP_ASSERT("mem_malloc: allocated memory properly aligned.",
-         ((mem_ptr_t)mem + SIZEOF_STRUCT_MEM) % MEM_ALIGNMENT == 0);
-        LWIP_ASSERT("mem_malloc: sanity check alignment",
-          (((mem_ptr_t)mem) & (MEM_ALIGNMENT-1)) == 0);
-
-        return (u8_t *)mem + SIZEOF_STRUCT_MEM;
-      }
-    }
-#if LWIP_ALLOW_MEM_FREE_FROM_OTHER_CONTEXT
-    /* if we got interrupted by a mem_free, try again */
-  } while(local_mem_free_count != 0);
-#endif /* LWIP_ALLOW_MEM_FREE_FROM_OTHER_CONTEXT */
-  LWIP_DEBUGF(MEM_DEBUG | LWIP_DBG_LEVEL_SERIOUS, ("mem_malloc: could not allocate %"S16_F" bytes\n", (s16_t)size));
-  MEM_STATS_INC(err);
-  LWIP_MEM_ALLOC_UNPROTECT();
-  sys_mutex_unlock(&mem_mutex);
-  return NULL;
-}
-
-#endif /* MEM_USE_POOLS */
-/**
- * Contiguously allocates enough space for count objects that are size bytes
- * of memory each and returns a pointer to the allocated memory.
- *
- * The allocated memory is filled with bytes of value zero.
- *
- * @param count number of objects to allocate
- * @param size size of the objects to allocate
- * @return pointer to allocated memory / NULL pointer if there is an error
- */
-void *mem_calloc(mem_size_t count, mem_size_t size)
-{
-  void *p;
-
-  /* allocate 'count' objects of size 'size' */
-  p = mem_malloc(count * size);
-  if (p) {
-    /* zero the memory */
-    memset(p, 0, count * size);
-  }
-  return p;
-}
-
-#endif /* !MEM_LIBC_MALLOC */