基于MCU无操作系统，简单而又强大的内存管理方法

#ifndef __MEMORY_H__#define __MEMORY_H__
#include "stdio.h"#include "string.h"#include "includes.h"//用户使用typedef struct{ void *addr; //申请到的内存的起始地址 uint32_t size; //申请到的内存的大小，按照块大小分配，大于等于申请大小 uint16_t tb; //申请表序号，申请内存时分配，释放内存时使用，用户不使用}DMEM;//若返回空，则申请失败DMEM *DynMemGet(uint32_t size);
void DynMemPut(DMEM *pDmem);
#endif //__MEMORY_H__

#include "memory.h"
#define DMEM_BLOCK_SIZE 256 //内存块大小为128字节#define DMEM_BLOCK_NUM 20 //内存块个数为40个#define DMEM_TOTAL_SIZE (DMEM_BLOCK_SIZE*DMEM_BLOCK_NUM) //内存总大小
static uint8_t DMEMORY[DMEM_TOTAL_SIZE];static DMEM_STATE DMEMS = {0};
typedef enum{ DMEM_FREE = 0, DMEM_USED = 1,}DMEM_USED_ITEM;
typedef struct{ DMEM_USED_ITEM used; //使用状态 uint16_t blk_s; //起始块序号 uint16_t blk_num; //块个数}DMEM_APPLY;
typedef struct{ DMEM_USED_ITEM tb_blk[DMEM_BLOCK_NUM]; DMEM tb_user[DMEM_BLOCK_NUM]; //用户申请内存信息 DMEM_APPLY tb_apply[DMEM_BLOCK_NUM]; //系统分配内存信息 uint16_t apply_num; //内存申请表占用数目 uint16_t blk_num; //内存块占用数目}DMEM_STATE;

DMEM *DynMemGet(uint32_t size){ uint16_t loop = 0; uint16_t find = 0; uint16_t blk_num_want = 0; DMEM * user = NULL; DMEM_APPLY *apply = NULL;
 //申请内存大小不能为0 if(size == 0) { return NULL; } //申请内存不可超过总内存大小 if(size > DMEM_TOTAL_SIZE) { return NULL; } //申请内存不可超过剩余内存大小 if(size > (DMEM_BLOCK_NUM - DMEMS.blk_num) * DMEM_BLOCK_SIZE) { return NULL; } //申请表必须有空余 if(DMEMS.apply_num >= DMEM_BLOCK_NUM) { return NULL; }
 //计算所需连续块的个数 blk_num_want = (size + DMEM_BLOCK_SIZE - 1) / DMEM_BLOCK_SIZE;
 //寻找申请表 for(loop = 0; loop < DMEM_BLOCK_NUM; loop++) { if(DMEMS.tb_apply[loop].used == DMEM_FREE) { apply = &DMEMS.tb_apply[loop]; //申请表已找到 user = &DMEMS.tb_user[loop]; //用户表对应找到 user->tb = loop; //申请表编号记录 user->size = blk_num_want * DMEM_BLOCK_SIZE; //分配大小计算 break; } }
 //没有找到可用申请表，理论上是不会出现此现象的，申请表剩余已在上面校验 if(loop == DMEM_BLOCK_NUM) { return NULL; }
 //寻找连续内存块 for(loop = 0; loop < DMEM_BLOCK_NUM; loop++) { if(DMEMS.tb_blk[loop] == DMEM_FREE) {//找到第一个空闲内存块 for(find = 1; (find < blk_num_want) && (loop + find < DMEM_BLOCK_NUM); find ++) {//找到下一个空闲内存块 if(DMEMS.tb_blk[loop + find] != DMEM_FREE) {//发现已使用内存块 break; } } if(find >= blk_num_want) {//寻找到的空闲内存块数目已经够用 user->addr = DMEMORY + loop * DMEM_BLOCK_SIZE; //计算申请到的内存的地址 apply->blk_s = loop; //记录申请到的内存块首序号 apply->blk_num = blk_num_want; //记录申请到的内存块数目 for(find = 0 ; find < apply->blk_num; find++) { DMEMS.tb_blk[loop + find] = DMEM_USED; } apply->used = DMEM_USED; //标记申请表已使用 DMEMS.apply_num += 1; DMEMS.blk_num += blk_num_want;
 return user; } else {//寻找到的空闲内存块不够用，从下一个开始找 loop += find; } } }
 //搜索整个内存块，未找到大小适合的空间 return NULL;}

void DynMemPut(DMEM *user){ uint16_t loop = 0; //若参数为空，直接返回 if(NULL == user) { return; }
 //释放内存空间 for(loop = DMEMS.tb_apply[user->tb].blk_s; loop < DMEMS.tb_apply[user->tb].blk_s + DMEMS.tb_apply[user->tb].blk_num; loop++) { DMEMS.tb_blk[loop] = DMEM_FREE; DMEMS.blk_num -= 1; } //释放申请表 DMEMS.tb_apply[user->tb].used = DMEM_FREE; DMEMS.apply_num -= 1;}