mem.c

基于STM32F107的UDP服务器程序

/**
 * @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 <[e-mail]>
 *         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 <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++) {
#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[next]) of the next 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)

/** the heap. we need one struct mem at the end and some room for alignment */
static u8_t ram_heap[MEM_SIZE_ALIGNED + (2*SIZEOF_STRUCT_MEM) + MEM_ALIGNMENT];
/** 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_sem_t mem_sem;

#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_arch_sem_wait(mem_sem, 0)
#define LWIP_MEM_FREE_UNPROTECT()  sys_sem_signal(mem_sem)
/* 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_realloc()
 *
 * 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 *)&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 *)&ram[nmem->next])->prev = (u8_t *)mem - ram;
  }

  /* plug hole backward */
  pmem = (struct mem *)&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 *)&ram[mem->next])->prev = (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 = LWIP_MEM_ALIGN(ram_heap);
  /* initialize the start of the heap */
  mem = (struct mem *)ram;
  mem->next = MEM_SIZE_ALIGNED; 
  mem->prev = 0;
  mem->used = 0;
  /* initialize the end of the heap */
  ram_end = (struct mem *)&ram[MEM_SIZE_ALIGNED];
  ram_end->used = 1;
  ram_end->next = MEM_SIZE_ALIGNED;
  ram_end->prev = MEM_SIZE_ALIGNED;

  mem_sem = sys_sem_new(1);

  /* initialize the lowest-free pointer to the start of the heap */
  lfree = (struct mem *)ram;

  MEM_STATS_AVAIL(avail, MEM_SIZE_ALIGNED);
}

/**
 * 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 | 2, ("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 | 3, ("mem_free: illegal memory\n"));
    /* protect mem stats from concurrent access */
    SYS_ARCH_PROTECT(lev);
    MEM_STATS_INC(illegal);
    SYS_ARCH_UNPROTECT(lev);