单片机模块化程序: μCOS-II中内存管理程序使用说明
前言
环形队列,链表,内存管理,这些典型的数据缓存处理方式
作为一个开发者是应该掌握的知识点
由于后面的文章涉及到了内存管理
故,这节先说一下内存管理
uCOSII中的内存管理源码
我把uCOS中的内存管理程序拷贝出来了
OS_MEM.C
/*
*********************************************************************************************************
* uC/OS-II
* The Real-Time Kernel
* MEMORY MANAGEMENT
*
* (c) Copyright 1992-1998, Jean J. Labrosse, Plantation, FL
* All Rights Reserved
*
* V2.00
*
* File : OS_MEM.C
* By : Jean J. Labrosse
*********************************************************************************************************
*/
#define OS_MEM_C_
#include "OS_MEM.h"
//#if OS_MEM_EN && OS_MAX_MEM_PART >= 2
/*
*********************************************************************************************************
* LOCAL GLOBAL VARIABLES
*********************************************************************************************************
*/
static OS_MEM *OSMemFreeList; /* Pointer to free list of memory partitions */
static OS_MEM OSMemTbl[OS_MAX_MEM_PART];/* Storage for memory partition manager */
/*$PAGE*/
/*
*********************************************************************************************************
* CREATE A MEMORY PARTITION
*
* Description : Create a fixed-sized memory partition that will be managed by uC/OS-II.
*
* Arguments : addr is the starting address of the memory partition
*
* nblks is the number of memory blocks to create from the partition.
*
* blksize is the size (in bytes) of each block in the memory partition.
*
* err is a pointer to a variable containing an error message which will be set by
* this function to either:
*
* OS_NO_ERR if the memory partition has been created correctly.
* OS_MEM_INVALID_PART no free partitions available
* OS_MEM_INVALID_BLKS user specified an invalid number of blocks (must be >= 2)
* OS_MEM_INVALID_SIZE user specified an invalid block size
* (must be greater than the size of a pointer)
* Returns : != (OS_MEM *)0 is the partition was created
* == (OS_MEM *)0 if the partition was not created because of invalid arguments or, no
* free partition is available.
*********************************************************************************************************
*/
OS_MEM *OSMemCreate (void *addr, INT32U nblks, INT32U blksize, INT8U *err)
{
OS_MEM *pmem;
INT8U *pblk;
void **plink;
INT32U i;
//注意这里 (INT8U *)addr 和 (INT8U)*addr 完全不同啊啊，前者 addr是指向的一个地址，而这个地址内数据不知道是什么类型的
//所以(INT8U *)说明这个地址的内容是INT8U型的，(INT8U *)addr 表示的是一个新的 addr，而后面(INT8U)*addr 表示把 *addr转换成
//一个八位的无符号整形数据
if (nblks < 2) { /* Must have at least 2 blocks per partition */
*err = OS_MEM_INVALID_BLKS;
return ((OS_MEM *)0);
}
if (blksize < sizeof(void *)) { /* Must contain space for at least a pointer */
*err = OS_MEM_INVALID_SIZE;
return ((OS_MEM *)0);
}
// OS_ENTER_CRITICAL();
pmem = OSMemFreeList; /* Get next free memory partition */
if (OSMemFreeList != (OS_MEM *)0) { /* See if pool of free partitions was empty */
OSMemFreeList = (OS_MEM *)OSMemFreeList->OSMemFreeList;
}
// OS_EXIT_CRITICAL();
if (pmem == (OS_MEM *)0) { /* See if we have a memory partition */
*err = OS_MEM_INVALID_PART;
return ((OS_MEM *)0);
}
plink = (void **)addr; /* Create linked list of free memory blocks */
pblk = (INT8U *)addr + blksize;
for (i = 0; i < (nblks - 1); i++) {
*plink = (void *)pblk;
plink = (void **)pblk;
pblk = pblk + blksize;
}
*plink = (void *)0; /* Last memory block points to NULL */
// OS_ENTER_CRITICAL();
pmem->OSMemAddr = addr; /* Store start address of memory partition */
pmem->OSMemFreeList = addr; /* Initialize pointer to pool of free blocks */
pmem->OSMemNFree = nblks; /* Store number of free blocks in MCB */
pmem->OSMemNBlks = nblks;
pmem->OSMemBlkSize = blksize; /* Store block size of each memory blocks */
// OS_EXIT_CRITICAL();
*err = OS_NO_ERR;
return (pmem);
}
/*$PAGE*/
/*
*********************************************************************************************************
* GET A MEMORY BLOCK
*
* Description : Get a memory block from a partition
*
* Arguments : pmem is a pointer to the memory partition control block
*
* err is a pointer to a variable containing an error message which will be set by this
* function to either:
*
* OS_NO_ERR if the memory partition has been created correctly.
* OS_MEM_NO_FREE_BLKS if there are no more free memory blocks to allocate to caller
*
* Returns : A pointer to a memory block if no error is detected
* A pointer to NULL if an error is detected
*********************************************************************************************************
*/
void *OSMemGet (OS_MEM *pmem, INT8U *err)
{
void *pblk;
// OS_ENTER_CRITICAL();
if (pmem->OSMemNFree > 0) { /* See if there are any free memory blocks */
pblk = pmem->OSMemFreeList; /* Yes, point to next free memory block */
pmem->OSMemFreeList = *(void **)pblk; /* Adjust pointer to new free list */
pmem->OSMemNFree--; /* One less memory block in this partition */
// OS_EXIT_CRITICAL();
*err = OS_NO_ERR; /* No error */
return (pblk); /* Return memory block to caller */
} else {
// OS_EXIT_CRITICAL();
*err = OS_MEM_NO_FREE_BLKS; /* No, Notify caller of empty memory partition */
return ((void *)0); /* Return NULL pointer to caller */
}
}
/*$PAGE*/
/*
*********************************************************************************************************
* INITIALIZE MEMORY PARTITION MANAGER
*
* Description : This function is called by uC/OS-II to initialize the memory partition manager. Your
* application MUST NOT call this function.
*
* Arguments : none
*
* Returns : none
*********************************************************************************************************
*/
void OSMemInit (void)
{
OS_MEM *pmem;
INT16U i;
pmem = (OS_MEM *)&OSMemTbl[0]; /* Point to memory control block (MCB) */
for (i = 0; i < (OS_MAX_MEM_PART - 1); i++) { /* Init. list of free memory partitions */
pmem->OSMemFreeList = (void *)&OSMemTbl[i+1]; /* Chain list of free partitions */
pmem->OSMemAddr = (void *)0; /* Store start address of memory partition */
pmem->OSMemNFree = 0; /* No free blocks */
pmem->OSMemNBlks = 0; /* No blocks */
pmem->OSMemBlkSize = 0; /* Zero size */
pmem++;
}
OSMemTbl[OS_MAX_MEM_PART - 1].OSMemFreeList = (void *)0;
OSMemFreeList = (OS_MEM *)&OSMemTbl[0];
}
/*$PAGE*/
/*
*********************************************************************************************************
* RELEASE A MEMORY BLOCK
*
* Description : Returns a memory block to a partition
*
* Arguments : pmem is a pointer to the memory partition control block
*
* pblk is a pointer to the memory block being released.
*
* Returns : OS_NO_ERR if the memory block was inserted into the partition
* OS_MEM_FULL if you are returning a memory block to an already FULL memory partition
* (You freed more blocks than you allocated!)
*********************************************************************************************************
*/
INT8U OSMemPut (OS_MEM *pmem, void *pblk)
{
// OS_ENTER_CRITICAL();
if (pmem->OSMemNFree >= pmem->OSMemNBlks) { /* Make sure all blocks not already returned */
// OS_EXIT_CRITICAL();
return (OS_MEM_FULL);
}
*(void **)pblk = pmem->OSMemFreeList; /* Insert released block into free block list */
pmem->OSMemFreeList = pblk;
pmem->OSMemNFree++; /* One more memory block in this partition */
// OS_EXIT_CRITICAL();
return (OS_NO_ERR); /* Notify caller that memory block was released */
}
/*$PAGE*/
/*
*********************************************************************************************************
* QUERY MEMORY PARTITION
*
* Description : This function is used to determine the number of free memory blocks and the number of
* used memory blocks from a memory partition.
*
* Arguments : pmem is a pointer to the memory partition control block
*
* pdata is a pointer to a structure that will contain information about the memory
* partition.
*
* Returns : OS_NO_ERR Always returns no error.
*********************************************************************************************************
*/
INT8U OSMemQuery (OS_MEM *pmem, OS_MEM_DATA *ppdata)
{
// OS_ENTER_CRITICAL();
ppdata->OSAddr = pmem->OSMemAddr;
ppdata->OSFreeList = pmem->OSMemFreeList;
ppdata->OSBlkSize = pmem->OSMemBlkSize;
ppdata->OSNBlks = pmem->OSMemNBlks;
ppdata->OSNFree = pmem->OSMemNFree;
// OS_EXIT_CRITICAL();
ppdata->OSNUsed = ppdata->OSNBlks - ppdata->OSNFree;
return (OS_NO_ERR);
}
//#endifOS_MEM.h
#ifndef OS_MEM_H_
#define OS_MEM_H_
#include "stm32f10x.h"
#ifndef OS_MEM_C_
#define OS_MEM_Cx_ extern
#else
#define OS_MEM_Cx_
#endif
#define OS_MAX_MEM_PART 4
#define OS_NO_ERR 0
#define OS_MEM_INVALID_PART 110
#define OS_MEM_INVALID_BLKS 111
#define OS_MEM_INVALID_SIZE 112
#define OS_MEM_NO_FREE_BLKS 113
#define OS_MEM_FULL 114
typedef unsigned char INT8U; //无符号8位数
typedef unsigned int INT16U; //无符号16位数
typedef unsigned long INT32U; //无符号32位数
typedef struct { /* MEMORY CONTROL BLOCK */
void *OSMemAddr; /* Pointer to beginning of memory partition */
void *OSMemFreeList; /* Pointer to list of free memory blocks */
INT32U OSMemBlkSize; /* Size (in bytes) of each block of memory */
INT32U OSMemNBlks; /* Total number of blocks in this partition */
INT32U OSMemNFree; /* Number of memory blocks remaining in this partition */
} OS_MEM;
typedef struct {
void *OSAddr; /* Pointer to the beginning address of the memory partition */
void *OSFreeList; /* Pointer to the beginning of the free list of memory blocks */
INT32U OSBlkSize; /* Size (in bytes) of each memory block */
INT32U OSNBlks; /* Total number of blocks in the partition */
INT32U OSNFree; /* Number of memory blocks free */
INT32U OSNUsed; /* Number of memory blocks used */
} OS_MEM_DATA;
OS_MEM *OSMemCreate (void *addr, INT32U nblks, INT32U blksize, INT8U *err);
void *OSMemGet (OS_MEM *pmem, INT8U *err);
void OSMemInit (void);
INT8U OSMemPut (OS_MEM *pmem, void *pblk);
INT8U OSMemQuery (OS_MEM *pmem, OS_MEM_DATA *ppdata);
#endifuCOSII提供的内存管理实质
一,实际上就是用一些程序对一个二维的数组进行管理
二,整个数组叫做 "内存分区"
三,数组的行数代表内存块的个数
四,数组的每一行叫做 "内存块",每一行的长度叫做内存块长度
五,申请内存块,实际上就是返回数组某一行的首地址,
咱可以把数据存储到那一行里面!
六,每一次申请内存块的时候,内部会判断哪一行没有被申请过
然后把哪一行的首地址返回过来
使用
一,创建内存
定义了一个二维数组,行数20(20个内存块)
列数16(每一个内存块最大存储16个数据)
二,申请一个内存块
三,往内存块里面存储数据
实际上就是存储到了那个二维数组里面
现在数组的第一行存储了数据
四,再申请一个,再存储数据
现在数组的第二行存储了数据
四,使用存储的数据
操作存储数据的首地址即可
总结
μCOS-II提供的内存管理实际上就是对一个二维的数组进行管理
事先先定义好内存块,和每个内存块长度
二维数组的行数代表内存块个数
二维数组的列数代表每个内存块的长度
申请内存块其实就是内部程序判断数组哪一行没有使用过
然后返回那一行的首地址
然后咱就可以往里面存数据
注意
往里面存储数据的时候不得超出内存块长度(数组每一行的列数)
有人可能会问,如果我有很大的数据量呢??
办法1.用多个内存块存储
办法2.设置内存块的长度足够长
补充1(释放使用的内存块)
咱使用完某一个内存块存储的数据以后需要告诉内部程序
释放这个内存块,以便这个内存块可以再次被申请使用
OSMemPut (OS_MEM *pmem, void *pblk)
第一个参数: 内存指针
第二个参数:内存块指针
补充2(查询内存分区信息)
本文参与 腾讯云自媒体分享计划，分享自作者个人站点/博客。
原始发表：2020-01-31 ，如有侵权请联系 cloudcommunity@tencent.com 删除
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