SOS-----lwip mem_init 疑惑

sklli

Dear 亲们： 
先谢谢谢。。。。。。

mem_init初始化时next设置为 mem->next = MEM_SIZE_ALIGNED;   这样的话，由于mem结构占用空间， 所以最大可分配的空间就只有MEM_SIZE_ALIGNED - SIZEOF_STRUCT_MEM；
为什么初始化时，不是这样配置了mem->next = MEM_SIZE_ALIGNED + SIZEOF_STRUCT_MEM;
                                                         ram_end = (struct mem *)(void *)&ram[MEM_SIZE_ALIGNED + SIZEOF_STRUCT_MEM];
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;      // 为什么不是mem->next = MEM_SIZE_ALIGNED + SIZEOF_STRUCT_MEM;
  mem->prev = 0;
  mem->used = 0;
  /* initialize the end of the heap */
  ram_end = (struct mem *)(void *)&ram[MEM_SIZE_ALIGNED];//为什么不是ram_end = (struct mem *)(void *)&ram[MEM_SIZE_ALIGNED + SIZEOF_STRUCT_MEM];
  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);
  }
}

正点原子

帮顶。。。。。