1、盡量不使用庫自帶的malloc和free。

#define Heap_Size 0x00000800unsigned char Heap_Mem[Heap_Size] = {0};

__user_initial_stackheapLDR     R0, =  Heap_Mem  ;  返回系統(tǒng)中堆內(nèi)存起始地址LDR     R1, =(Stack_Mem + Stack_Size)LDR     R2, = (Heap_Mem +  Heap_Size); 返回系統(tǒng)中堆內(nèi)存的結(jié)束地址LDR     R3, = Stack_MemBX      LR

unsigned char mem_buffer[512];unsigned char *mem_offset = & mem_buffer;void *malloc(int size){unsigned char *tmp = mem_offset;    mem_offset += size;return (void *)tmp;}void free(void *mem){ mem_offset = mem;}

2、不用malloc、free的原因

3、 更好的替代方案：內(nèi)存池。

#define MEM_BUFFER_LEN  5    //內(nèi)存塊的數(shù)量#define MEM_BUFFER_SIZE 256 //每塊內(nèi)存的大小
//內(nèi)存池的描述，使用聯(lián)合體，體現(xiàn)窮人的智慧。就如，我一同學(xué)說的：一個(gè)字節(jié)，恨不得掰成8個(gè)字節(jié)來用。typedef union mem {struct list_head list;unsigned char buffer[MEM_BUFFER_SIZE];}mem_t;
static union mem gmem[MEM_BUFFER_LEN];
LIST_HEAD(mem_pool);
//分配內(nèi)存void *mem_pop(){    union mem *ret = NULL;    psr_t psr;
    psr = ENTER_CRITICAL();    if(!list_empty(&mem_pool)) { //有可用的內(nèi)存池         ret = list_first_entry(&mem_pool, union mem, list);        //printf("mem_pool = 0x%p  ret = 0x%p
", &mem_pool, &ret->list);        list_del(&ret->list); } EXIT_CRITICAL(psr); return ret;//->buffer;}

//回收內(nèi)存void mem_push(void *mem){    union mem *tmp = NULL;     psr_t psr;
    tmp = (void *)mem;//container_of(mem, struct mem, buffer);    psr = ENTER_CRITICAL();    list_add(&tmp->list, &mem_pool);    //printf("free = 0x%p
", &tmp->list);
    EXIT_CRITICAL(psr);}
//初始化內(nèi)存池void mem_pool_init(){    int i;    psr_t psr;    psr = ENTER_CRITICAL();    for(i=0; i        list_add(&(gmem[i].list), &mem_pool);        //printf("add mem 0x%p
", &(gmem[i].list)); } EXIT_CRITICAL(psr);}