改进的malloc/free实现源码

此malloc/free实现增加空闲块添加功能：AddFreeMemBlock

#include "stdafx.h"#include <stdlib.h>#include <stdio.h>#include <time.h>#include <memory.h>typedef struct tagMemMgr_t{struct tagMemMgr_t *pNext;struct tagMemMgr_t *pPrev;intSize;} MemMgr_t;#define MEM_HDR_SIZEsizeof(MemMgr_t)static MemMgr_t*FreeHeader;void InitMemMgr(void * pMemory, int Size){if(NULL == pMemory || Size <= MEM_HDR_SIZE) {FreeHeader = NULL;return;}FreeHeader= (MemMgr_t *)pMemory;FreeHeader->pNext = NULL;FreeHeader->pPrev = NULL;FreeHeader->Size  = Size - MEM_HDR_SIZE;}void *_malloc(int Size){MemMgr_t *p;int RemainingSize;Size = (Size + 3)/4 * 4;p = FreeHeader;while(NULL != p) {if (p->Size >= Size) {break;}else {p = p->pNext;}}if (NULL == p) return NULL;RemainingSize = p->Size - Size;if(RemainingSize > MEM_HDR_SIZE) { /* split the free block into 2 free block */MemMgr_t *q;q = (MemMgr_t *)((char *)p + MEM_HDR_SIZE + Size);q->Size = RemainingSize - MEM_HDR_SIZE;q->pNext = p->pNext;q->pPrev = p->pPrev;if(p->pPrev == NULL) {FreeHeader = q;}else {p->pPrev->pNext = q;}if(p->pNext != NULL) {p->pNext->pPrev = q;}p->Size = Size;}else {/* delete p from the free list */if(p->pPrev == NULL) {FreeHeader = p->pNext;}else {p->pPrev->pNext = p->pNext;}if(p->pNext != NULL) {p->pNext->pPrev = p->pPrev;}}return (char *)p + MEM_HDR_SIZE;}/* q merges to p */static MemMgr_t * MemMerge(MemMgr_t *p, MemMgr_t *q){if(q == NULL) {return NULL;}if(((char *)p + MEM_HDR_SIZE + p->Size) == (char *)q) {/* delete q */p->pNext = q->pNext;if(q->pNext != NULL) {q->pNext->pPrev = p;}p->Size += MEM_HDR_SIZE + q->Size;return p;}else {return NULL;}}void _free(void * pMem){MemMgr_t *pToFree, *p, *q;if(NULL == pMem) return;pToFree = (MemMgr_t *)((char *)pMem - MEM_HDR_SIZE);if(FreeHeader == NULL) {FreeHeader = pToFree;FreeHeader->pNext = NULL;FreeHeader->pPrev = NULL;return;}q = FreeHeader;p = q->pPrev;while(q != NULL && pToFree > q) {p = q;q = q->pNext;}if(p == NULL) { /* pToFree should be the first free block */pToFree->pNext = FreeHeader;pToFree->pPrev = NULL;FreeHeader->pPrev = pToFree;FreeHeader = pToFree;MemMerge(FreeHeader, FreeHeader->pNext);}else {if(q == NULL) { /* pToFree as the last free block */pToFree->pNext = NULL;pToFree->pPrev = p;p->pNext = pToFree;MemMerge(p, pToFree);}else { /* pToFree insert into the free list */pToFree->pNext = q;pToFree->pPrev = p;p->pNext = pToFree;q->pPrev = pToFree;if(NULL != MemMerge(p, pToFree)) {MemMerge(p, q);}else {MemMerge(pToFree, q);}}}}void AddFreeMemBlock(void * pMem, int Size){if(NULL == pMem || Size <= MEM_HDR_SIZE) {return;}((MemMgr_t *)pMem)->Size = Size - MEM_HDR_SIZE;_free((char *)pMem + MEM_HDR_SIZE);}static int OutputFreeList(void){int Count = 0;int TotalSize = 0;MemMgr_t *p = FreeHeader;while(p != NULL) {Count++;TotalSize += p->Size;printf("%08X(% 5d)->", p, p->Size);if(Count % 30 == 0) {printf("\n");}p = p->pNext;}printf("\nFreeListLength:%d(%d).\n", Count, TotalSize);return Count;}#defineMAX_ALLOC_SIZE1024#defineTEST_MEM_ARRAY_SIZE1000#defineFREE_MEM_SIZE(MAX_ALLOC_SIZE * 600) //TEST_MEM_ARRAY_SIZE)typedef void * void_p_t;int main(int argc, char* argv[]){void_p_t pMem[TEST_MEM_ARRAY_SIZE];void_p_t pAddMem[10];int i;int AddMemIdx;int RunTimes = 1000000;if(argc > 1) {sscanf(argv[1], "%i", &RunTimes);}for(i = 0; i < TEST_MEM_ARRAY_SIZE; i++) {pMem[i] = NULL;}for(i = 0; i < sizeof(pAddMem)/sizeof(pAddMem[0]); i++) {pAddMem[i] = NULL;}InitMemMgr(NULL, 0);i = 0;AddMemIdx = 0;srand((unsigned)time(NULL));while(RunTimes--) {int MemLoc;int MemSize;MemLoc = rand() % TEST_MEM_ARRAY_SIZE;if(pMem[MemLoc] != NULL) {_free(pMem[MemLoc]);}MemSize = rand() % MAX_ALLOC_SIZE;pMem[MemLoc] = _malloc(MemSize);if(NULL == pMem[MemLoc]) {printf("%dth alloc:%d, Out of memory.\n", i, MemSize);pAddMem[AddMemIdx] = malloc(FREE_MEM_SIZE);printf("AddFreeMemBlockAddress:%08X(%d)\n", pAddMem[AddMemIdx], (int)FREE_MEM_SIZE);AddFreeMemBlock(pAddMem[AddMemIdx], FREE_MEM_SIZE);AddMemIdx++;continue;}memset(pMem[MemLoc], 0x00, MemSize);//printf("%08X(% 5d)% 8d\n", pMem[MemLoc], MemSize, i);i++;}OutputFreeList();for(i = 0; i < TEST_MEM_ARRAY_SIZE; i++) {if(pMem[i] != NULL) {_free(pMem[i]);}}OutputFreeList();for(i = 0; i < sizeof(pAddMem)/sizeof(pAddMem[0]); i++) {if(NULL != pAddMem[i]) {free(pAddMem[i]);}}return 0;}