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); } //#endif
OS_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);
#endif
uCOSII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)
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发表于 2020-9-21 09:47:33
