干貨分享！嵌入式裸機(jī)編程中使用malloc、free會怎樣？

Heap_Size EQU 0x00000800AREA HEAP, NOINIT, READWRITE, ALIGN=3__heap_baseHeap_Mem SPACE Heap_Size__heap_limit

#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;}

#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：一個字節(jié)，恨不得掰成8個字節(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\n", &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\n", &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\n", &(gmem[i].list)); } EXIT_CRITICAL(psr);}