概述
在实际项目中,有些单片机资源紧缺,需要mallloc内存,库又没有自带malloc函数时,此时,就需要手动编写,在此做个笔录。(已在项目上使用),还可进入对齐管理机制。
直接上源码 ^_^
一、示例1:
1、mem_malloc.h文件
cpp
#ifndef __MEM_MALLOC_H__
#define __MEM_MALLOC_H__
#ifdef __cplusplus
extern "C" {
#endif
#include <stddef.h>
void* mem_malloc(size_t size);
void mem_free(void* ptr);
#ifdef __cplusplus
}
#endif
#endif
2、mem_malloc.c文件
cpp
#include "mem_malloc.h"
#include "stdint.h"
// 定义内存块结构
typedef struct MemoryBlock {
size_t size;
struct MemoryBlock* next;
} MemoryBlock;
// 定义内存池起始地址
#define MEMORY_POOL_SIZE 1024
static uint8_t memoryPool[MEMORY_POOL_SIZE];
// 全局指针,指向内存池起始位置
static MemoryBlock* memoryPoolPtr = NULL;
// 初始化内存池
void memoryPoolInit(void)
{
memoryPoolPtr = (MemoryBlock*)memoryPool;
memoryPoolPtr->size = MEMORY_POOL_SIZE - sizeof(MemoryBlock);
memoryPoolPtr->next = NULL;
}
// 分配内存
void* mem_malloc(size_t size)
{
//memoryPoolInit();
if (size == 0)
return NULL;
MemoryBlock* currentBlock = memoryPoolPtr;
//MemoryBlock* prevBlock = NULL;
// 遍历内存池中的内存块,找到合适大小的内存块
while (currentBlock != NULL) {
if (currentBlock->size >= size + sizeof(MemoryBlock)) {
// 如果当前内存块大于所需内存,分配内存
if (currentBlock->size >= size + sizeof(MemoryBlock) + sizeof(size_t)) {
MemoryBlock* newBlock = (MemoryBlock*)((uint8_t*)currentBlock + sizeof(MemoryBlock) + size);
newBlock->size = currentBlock->size - sizeof(MemoryBlock) - size;
newBlock->next = currentBlock->next;
currentBlock->next = newBlock;
currentBlock->size = size;
}
// 返回分配的内存块的地址
return (uint8_t*)currentBlock + sizeof(MemoryBlock);
}
//prevBlock = currentBlock;
currentBlock = currentBlock->next;
}
// 没有足够的内存块可供分配
return NULL;
}
// 释放内存
void mem_free(void* ptr)
{
if (ptr == NULL)
return;
MemoryBlock* block = (MemoryBlock*)((uint8_t*)ptr - sizeof(MemoryBlock));
block->next = memoryPoolPtr;
memoryPoolPtr = block;
}
// 示例代码
int main(void)
{
// 初始化内存池
memoryPoolInit();
// 分配内存
int* intPtr = (int*)mem_malloc(sizeof(int));
if (intPtr != NULL) {
*intPtr = 42;
free(intPtr);
}
return 0;
}
二、示例2:
cpp
#include <stdio.h>
#define MEMORY_POOL_SIZE (1024 * 2)
unsigned char memoryBuff[MEMORY_POOL_SIZE];
typedef struct {
unsigned char* start;
size_t size;
} MemoryBlock;
static MemoryBlock memoryBlocks[MEMORY_POOL_SIZE] = { 0 };
static int numBlocks = 0;
// 从内存池中分配内存
void* mem_malloc(size_t size)
{
// 寻找空闲块
for (int i = 0; i < numBlocks; i++) {
if (memoryBlocks[i].size == 0 && size <= MEMORY_POOL_SIZE) {
// 找到合适大小的内存块,返回内存块地址
memoryBlocks[i].start = memoryBuff;
memoryBlocks[i].size = size;
return memoryBlocks[i].start;
}
}
// 分配新的块
if (numBlocks < MEMORY_POOL_SIZE) {
memoryBlocks[numBlocks].start = memoryBuff + numBlocks;
memoryBlocks[numBlocks].size = size;
numBlocks++;
return memoryBlocks[numBlocks - 1].start;
}
// 分配失败
return NULL;
}
void mem_free(void* ptr)
{
// 查找要释放的块
for (int i = 0; i < numBlocks; i++) {
if (memoryBlocks[i].start == ptr) {
memoryBlocks[i].size = 0;
break;
}
}
}
int main(void)
{
// 使用mem_malloc和mem_free进行内存管理
unsigned char* ptr1 = (unsigned char*)mem_malloc(50);
unsigned char* ptr2 = (unsigned char*)mem_malloc(100);
if (ptr1 != NULL && ptr2 != NULL) {
// 使用分配的内存
for (int i = 0; i < 50; i++) {
ptr1[i] = i;
}
for (int i = 0; i < 100; i++) {
ptr2[i] = i + 50;
}
// 打印分配的内存
printf("ptr1: ");
for (int i = 0; i < 50; i++) {
printf("%d ", ptr1[i]);
}
printf("\n");
printf("ptr2: ");
for (int i = 0; i < 100; i++) {
printf("%d ", ptr2[i]);
}
printf("\n");
}
mem_free(ptr1);
mem_free(ptr2);
return 0;
}
三、运行结果
四、总结
希望能帮助到你。