uC/OS-II 函數之內存管理相關函數 · uC/OS-II函數介紹

上文主要介紹了郵箱管理相關的函數，本文介紹內存管理相關的函數：OSMemCreate()內存塊創建函數，OSMemGet()函數，OSMemPut()函數，OSMemQuery()函數.以前用過的uC/OS-II筆記分享到這里。 ## 內存管理介紹在ANSI C中可以用malloc()和free()兩個函數動態地分配內存和釋放內存。但是，在嵌入式實時操作系統中，多次這樣做會把原來很大的一塊連續內存區域，逐漸地分割成許多非常小而且彼此又不相鄰的內存區域，也就是內存碎片。由于這些碎片的大量存在，使得程序到后來連非常小的內存也分配不到。另外，由于內存管理算法的原因，malloc()和free()函數執行時間是不確定的。在μC/OS-II中，操作系統把連續的大塊內存按分區來管理。每個分區中包含有整數個大小相同的內存塊。利用這種機制，μC/OS-II 對malloc()和free()函數進行了改進，使得它們可以分配和釋放固定大小的內存塊。這樣一來，malloc()和free()函數的執行時間也是固定的了。在一個系統中可以有多個內存分區。這樣，用戶的應用程序就可以從不同的內存分區中得到不同大小的內存塊。但是，特定的內存塊在釋放時必須重新放回它以前所屬于的內存分區。顯然，采用這樣的內存管理算法，上面的內存碎片問題就得到了解決。為了便于內存的管理，在μC/OS-II中使用內存控制塊（memory control blocks）的數據結構來跟蹤每一個內存分區，系統中的每個內存分區都有它自己的內存控制塊。內存控制塊的定義如下： ~~~ typedef struct { void *OSMemAddr; //指向內存分區起始地址的指針 void *OSMemFreeList; //是指向下一個空閑內存控制塊或者下一個空閑的內存塊的指針 INT32U OSMemBlkSize; //是內存分區中內存塊的大小 INT32U OSMemNBlks; //內存分區中總的內存塊數量 INT32U OSMemNFree; //內存分區中當前可以得空閑內存塊數量 } OS_MEM; ~~~ 如果要在μC/OS-II中使用內存管理，需要在OS_CFG.H文件中將開關量OS_MEM_EN設置為1。這樣μC/OS-II 在啟動時就會對內存管理器進行初始化[由OSInit()調用OSMemInit()實現]。常數OS_MAX_MEM_PART（見文件OS_CFG.H）定義了最大的內存分區數，該常數值最小應為2。 ## 注意的事項使用內存管理模塊需要做的工作還有： 1．打開配置文件OS_CFG.H，將開關量OS_MEM_EN設置為1： #define OS_MEM_EN 0 2．打開配置文件OS_CFG.H，設置系統要建立的任務分區的數量： #define OS_MAX_MEM_PART 2 ## OSMemCreate()內存塊創建函數 1 主要作用：該函數建立并初始化一個用于動態內存分配的區域，該內存區域包含指定數目的、大小確定的內存塊。應用可以動態申請這些內存塊并在用完后將其釋放回這個內存區域。該函數的返回值就是指向這個內存區域控制塊的指針，并作為OSMemGet()，OSMemPut()，OSMemQuery() 等相關調用的參數。 2函數原型：OS_MEM *OSMemCreate( void *addr, INT32U nblks, INT32U blksize, INT8U *err ); 3參數說明：addr 建立的內存區域的起始地址。可以使用靜態數組或在系統初始化時使用 malloc() 函數來分配這個區域的空間。 nblks 內存塊的數目。每一個內存區域最少需要定義兩個內存塊。 blksize 每個內存塊的大小，最小應該能夠容納一個指針變量。 err 是指向包含錯誤碼的變量的指針。Err可能是如下幾種情況： OS_NO_ERR ：成功建立內存區域。 OS_MEM_INVALID_ADDR ：非法地址，即地址為空指針。 OS_MEM_INVALID_PART ：沒有空閑的內存區域。 OS_MEM_INVALID_BLKS ：沒有為內存區域建立至少兩個內存塊。 OS_MEM_INVALID_SIZE ：內存塊大小不足以容納一個指針變量。 5、函數主體在os_men.c中 4返回值說明： OSMemCreate() 函數返回指向所創建的內存區域控制塊的指針。如果創建失敗，函數返回空指針。 ## OSMemGet()函數 1 主要作用：該函數用于從內存區域分配一個內存塊。用戶程序必須知道所建立的內存塊的大小，并必須在使用完內存塊后釋放它。可以多次調用 OSMemGet() 函數。它的返回值就是指向所分配內存塊的指針，并作為 OSMemPut() 函數的參數。 2函數原型：void *OSMemGet(OS_MEM *pmem, INT8U *err); 3參數說明：pmem 是指向內存區域控制塊的指針，可以從 OSMemCreate() 函數的返回值中得到。 err 是指向包含錯誤碼的變量的指針。Err可能是如下情況： OS_NO_ERR ：成功得到一個內存塊。 OS_MEM_NO_FREE_BLKS ：內存區域中已經沒有足夠的內存塊。 4返回值說明： OSMemGet() 函數返回指向所分配內存塊的指針。如果沒有可分配的內存塊，OSMemGet() 函數返回空指針。 5、函數主體在os_men.c中 ## OSMemPut() 1 主要作用：該函數用于釋放一個內存塊，內存塊必須釋放回它原先所在的內存區域，否則會造成系統錯誤。 2函數原型：INT8U OSMemPut (OS_MEM *pmem, void *pblk); 3參數說明：pmem 是指向內存區域控制塊的指針，可以從 OSMemCreate() 函數的返回值中得到。 pblk 是指向將被釋放的內存塊的指針。 4返回值說明： OSMemPut() 函數的返回值為下述之一： OS_NO_ERR ：成功釋放內存塊 OS_MEM_FULL ：內存區域已滿，不能再接受更多釋放的內存塊。這種情況說明用戶程序出現了錯誤，釋放了多于用 OSMemGet() 函數得到的內存塊。 5、函數主體在os_men.c中 ## OSMemQuery() 1 主要作用：該函數用于得到內存區域的信息。 2函數原型：INT8U OSMemQuery(OS_MEM *pmem, OS_MEM_DATA *pdata); 3參數說明：pmem 是指向內存區域控制塊的指針，可以從 OSMemCreate() 函數的返回值中得到。 pdata 是一個指向 OS_MEM_DATA 數據結構的指針，該數據結構包含了以下的域： ~~~ void OSAddr; /* 指向內存區域起始地址的指針 */ void OSFreeList; /* 指向空閑內存塊列表起始地址的指針 */ INT32U OSBlkSize; /* 每個內存塊的大小 */ INT32U OSNBlks; /* 該內存區域中的內存塊總數 */ INT32U OSNFree; /* 空閑的內存塊數目 */ INT32U OSNUsed; /* 已使用的內存塊數目 */ ~~~ 4返回值說明：函數返回值總是OS_NO_ERR。 5、函數主體在os_men.c中 ## 附os_men.c代碼 ~~~ /* ********************************************************************************************************* * uC/OS-II * The Real-Time Kernel * MEMORY MANAGEMENT * * (c) Copyright 1992-2013, Micrium, Weston, FL * All Rights Reserved * * File : OS_MEM.C * By : Jean J. Labrosse * Version : V2.92.08 * * LICENSING TERMS: * --------------- * uC/OS-II is provided in source form for FREE evaluation, for educational use or for peaceful research. * If you plan on using uC/OS-II in a commercial product you need to contact Micrium to properly license * its use in your product. We provide ALL the source code for your convenience and to help you experience * uC/OS-II. The fact that the source is provided does NOT mean that you can use it without paying a * licensing fee. ********************************************************************************************************* */ #define MICRIUM_SOURCE #ifndef OS_MASTER_FILE #include <ucos_ii.h> #endif #if (OS_MEM_EN > 0u) && (OS_MAX_MEM_PART > 0u) /* ********************************************************************************************************* * 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. * * perr is a pointer to a variable containing an error message which will be set by * this function to either: * * OS_ERR_NONE if the memory partition has been created correctly. * OS_ERR_MEM_INVALID_ADDR if you are specifying an invalid address for the memory * storage of the partition or, the block does not align * on a pointer boundary * OS_ERR_MEM_INVALID_PART no free partitions available * OS_ERR_MEM_INVALID_BLKS user specified an invalid number of blocks (must be >= 2) * OS_ERR_MEM_INVALID_SIZE user specified an invalid block size * - must be greater than the size of a pointer * - must be able to hold an integral number of pointers * 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 *perr) { OS_MEM *pmem; INT8U *pblk; void **plink; INT32U loops; INT32U i; #if OS_CRITICAL_METHOD == 3u /* Allocate storage for CPU status register */ OS_CPU_SR cpu_sr = 0u; #endif #ifdef OS_SAFETY_CRITICAL if (perr == (INT8U *)0) { OS_SAFETY_CRITICAL_EXCEPTION(); return ((OS_MEM *)0); } #endif #ifdef OS_SAFETY_CRITICAL_IEC61508 if (OSSafetyCriticalStartFlag == OS_TRUE) { OS_SAFETY_CRITICAL_EXCEPTION(); return ((OS_MEM *)0); } #endif #if OS_ARG_CHK_EN > 0u if (addr == (void *)0) { /* Must pass a valid address for the memory part.*/ *perr = OS_ERR_MEM_INVALID_ADDR; return ((OS_MEM *)0); } if (((INT32U)addr & (sizeof(void *) - 1u)) != 0u){ /* Must be pointer size aligned */ *perr = OS_ERR_MEM_INVALID_ADDR; return ((OS_MEM *)0); } if (nblks < 2u) { /* Must have at least 2 blocks per partition */ *perr = OS_ERR_MEM_INVALID_BLKS; return ((OS_MEM *)0); } if (blksize < sizeof(void *)) { /* Must contain space for at least a pointer */ *perr = OS_ERR_MEM_INVALID_SIZE; return ((OS_MEM *)0); } #endif 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 */ *perr = OS_ERR_MEM_INVALID_PART; return ((OS_MEM *)0); } plink = (void **)addr; /* Create linked list of free memory blocks */ pblk = (INT8U *)addr; loops = nblks - 1u; for (i = 0u; i < loops; i++) { pblk += blksize; /* Point to the FOLLOWING block */ *plink = (void *)pblk; /* Save pointer to NEXT block in CURRENT block */ plink = (void **)pblk; /* Position to NEXT block */ } *plink = (void *)0; /* Last memory block points to NULL */ 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 */ *perr = OS_ERR_NONE; return (pmem); } /*$PAGE*/ /* ********************************************************************************************************* * GET A MEMORY BLOCK * * Description : Get a memory block from a partition * * Arguments : pmem is a pointer to the memory partition control block * * perr is a pointer to a variable containing an error message which will be set by this * function to either: * * OS_ERR_NONE if the memory partition has been created correctly. * OS_ERR_MEM_NO_FREE_BLKS if there are no more free memory blocks to allocate to caller * OS_ERR_MEM_INVALID_PMEM if you passed a NULL pointer for 'pmem' * * Returns : A pointer to a memory block if no error is detected * A pointer to NULL if an error is detected ********************************************************************************************************* */ void *OSMemGet (OS_MEM *pmem, INT8U *perr) { void *pblk; #if OS_CRITICAL_METHOD == 3u /* Allocate storage for CPU status register */ OS_CPU_SR cpu_sr = 0u; #endif #ifdef OS_SAFETY_CRITICAL if (perr == (INT8U *)0) { OS_SAFETY_CRITICAL_EXCEPTION(); return ((void *)0); } #endif #if OS_ARG_CHK_EN > 0u if (pmem == (OS_MEM *)0) { /* Must point to a valid memory partition */ *perr = OS_ERR_MEM_INVALID_PMEM; return ((void *)0); } #endif OS_ENTER_CRITICAL(); if (pmem->OSMemNFree > 0u) { /* See if there are any free memory blocks */ pblk = pmem->OSMemFreeList; /* Yes, point to next free memory block */ pmem->OSMemFreeList = *(void **)pblk; /* Adjust pointer to new free list */ pmem->OSMemNFree--; /* One less memory block in this partition */ OS_EXIT_CRITICAL(); *perr = OS_ERR_NONE; /* No error */ return (pblk); /* Return memory block to caller */ } OS_EXIT_CRITICAL(); *perr = OS_ERR_MEM_NO_FREE_BLKS; /* No, Notify caller of empty memory partition */ return ((void *)0); /* Return NULL pointer to caller */ } /*$PAGE*/ /* ********************************************************************************************************* * GET THE NAME OF A MEMORY PARTITION * * Description: This function is used to obtain the name assigned to a memory partition. * * Arguments : pmem is a pointer to the memory partition * * pname is a pointer to a pointer to an ASCII string that will receive the name of the memory partition. * * perr is a pointer to an error code that can contain one of the following values: * * OS_ERR_NONE if the name was copied to 'pname' * OS_ERR_MEM_INVALID_PMEM if you passed a NULL pointer for 'pmem' * OS_ERR_PNAME_NULL You passed a NULL pointer for 'pname' * OS_ERR_NAME_GET_ISR You called this function from an ISR * * Returns : The length of the string or 0 if 'pmem' is a NULL pointer. ********************************************************************************************************* */ #if OS_MEM_NAME_EN > 0u INT8U OSMemNameGet (OS_MEM *pmem, INT8U **pname, INT8U *perr) { INT8U len; #if OS_CRITICAL_METHOD == 3u /* Allocate storage for CPU status register */ OS_CPU_SR cpu_sr = 0u; #endif #ifdef OS_SAFETY_CRITICAL if (perr == (INT8U *)0) { OS_SAFETY_CRITICAL_EXCEPTION(); return (0u); } #endif #if OS_ARG_CHK_EN > 0u if (pmem == (OS_MEM *)0) { /* Is 'pmem' a NULL pointer? */ *perr = OS_ERR_MEM_INVALID_PMEM; return (0u); } if (pname == (INT8U **)0) { /* Is 'pname' a NULL pointer? */ *perr = OS_ERR_PNAME_NULL; return (0u); } #endif if (OSIntNesting > 0u) { /* See if trying to call from an ISR */ *perr = OS_ERR_NAME_GET_ISR; return (0u); } OS_ENTER_CRITICAL(); *pname = pmem->OSMemName; len = OS_StrLen(*pname); OS_EXIT_CRITICAL(); *perr = OS_ERR_NONE; return (len); } #endif /*$PAGE*/ /* ********************************************************************************************************* * ASSIGN A NAME TO A MEMORY PARTITION * * Description: This function assigns a name to a memory partition. * * Arguments : pmem is a pointer to the memory partition * * pname is a pointer to an ASCII string that contains the name of the memory partition. * * perr is a pointer to an error code that can contain one of the following values: * * OS_ERR_NONE if the name was copied to 'pname' * OS_ERR_MEM_INVALID_PMEM if you passed a NULL pointer for 'pmem' * OS_ERR_PNAME_NULL You passed a NULL pointer for 'pname' * OS_ERR_MEM_NAME_TOO_LONG if the name doesn't fit in the storage area * OS_ERR_NAME_SET_ISR if you called this function from an ISR * * Returns : None ********************************************************************************************************* */ #if OS_MEM_NAME_EN > 0u void OSMemNameSet (OS_MEM *pmem, INT8U *pname, INT8U *perr) { #if OS_CRITICAL_METHOD == 3u /* Allocate storage for CPU status register */ OS_CPU_SR cpu_sr = 0u; #endif #ifdef OS_SAFETY_CRITICAL if (perr == (INT8U *)0) { OS_SAFETY_CRITICAL_EXCEPTION(); return; } #endif #if OS_ARG_CHK_EN > 0u if (pmem == (OS_MEM *)0) { /* Is 'pmem' a NULL pointer? */ *perr = OS_ERR_MEM_INVALID_PMEM; return; } if (pname == (INT8U *)0) { /* Is 'pname' a NULL pointer? */ *perr = OS_ERR_PNAME_NULL; return; } #endif if (OSIntNesting > 0u) { /* See if trying to call from an ISR */ *perr = OS_ERR_NAME_SET_ISR; return; } OS_ENTER_CRITICAL(); pmem->OSMemName = pname; OS_EXIT_CRITICAL(); *perr = OS_ERR_NONE; } #endif /*$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_ERR_NONE if the memory block was inserted into the partition * OS_ERR_MEM_FULL if you are returning a memory block to an already FULL memory * partition (You freed more blocks than you allocated!) * OS_ERR_MEM_INVALID_PMEM if you passed a NULL pointer for 'pmem' * OS_ERR_MEM_INVALID_PBLK if you passed a NULL pointer for the block to release. ********************************************************************************************************* */ INT8U OSMemPut (OS_MEM *pmem, void *pblk) { #if OS_CRITICAL_METHOD == 3u /* Allocate storage for CPU status register */ OS_CPU_SR cpu_sr = 0u; #endif #if OS_ARG_CHK_EN > 0u if (pmem == (OS_MEM *)0) { /* Must point to a valid memory partition */ return (OS_ERR_MEM_INVALID_PMEM); } if (pblk == (void *)0) { /* Must release a valid block */ return (OS_ERR_MEM_INVALID_PBLK); } #endif OS_ENTER_CRITICAL(); if (pmem->OSMemNFree >= pmem->OSMemNBlks) { /* Make sure all blocks not already returned */ OS_EXIT_CRITICAL(); return (OS_ERR_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_ERR_NONE); /* Notify caller that memory block was released */ } /*$PAGE*/ /* ********************************************************************************************************* * QUERY MEMORY PARTITION * * Description : This function is used to determine the number of free memory blocks and the number of * used memory blocks from a memory partition. * * Arguments : pmem is a pointer to the memory partition control block * * p_mem_data is a pointer to a structure that will contain information about the memory * partition. * * Returns : OS_ERR_NONE if no errors were found. * OS_ERR_MEM_INVALID_PMEM if you passed a NULL pointer for 'pmem' * OS_ERR_MEM_INVALID_PDATA if you passed a NULL pointer to the data recipient. ********************************************************************************************************* */ #if OS_MEM_QUERY_EN > 0u INT8U OSMemQuery (OS_MEM *pmem, OS_MEM_DATA *p_mem_data) { #if OS_CRITICAL_METHOD == 3u /* Allocate storage for CPU status register */ OS_CPU_SR cpu_sr = 0u; #endif #if OS_ARG_CHK_EN > 0u if (pmem == (OS_MEM *)0) { /* Must point to a valid memory partition */ return (OS_ERR_MEM_INVALID_PMEM); } if (p_mem_data == (OS_MEM_DATA *)0) { /* Must release a valid storage area for the data */ return (OS_ERR_MEM_INVALID_PDATA); } #endif OS_ENTER_CRITICAL(); p_mem_data->OSAddr = pmem->OSMemAddr; p_mem_data->OSFreeList = pmem->OSMemFreeList; p_mem_data->OSBlkSize = pmem->OSMemBlkSize; p_mem_data->OSNBlks = pmem->OSMemNBlks; p_mem_data->OSNFree = pmem->OSMemNFree; OS_EXIT_CRITICAL(); p_mem_data->OSNUsed = p_mem_data->OSNBlks - p_mem_data->OSNFree; return (OS_ERR_NONE); } #endif /* OS_MEM_QUERY_EN */ /*$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 * * Note(s) : This function is INTERNAL to uC/OS-II and your application should not call it. ********************************************************************************************************* */ void OS_MemInit (void) { #if OS_MAX_MEM_PART == 1u OS_MemClr((INT8U *)&OSMemTbl[0], sizeof(OSMemTbl)); /* Clear the memory partition table */ OSMemFreeList = (OS_MEM *)&OSMemTbl[0]; /* Point to beginning of free list */ #if OS_MEM_NAME_EN > 0u OSMemFreeList->OSMemName = (INT8U *)"?"; /* Unknown name */ #endif #endif #if OS_MAX_MEM_PART >= 2u OS_MEM *pmem; INT16U i; OS_MemClr((INT8U *)&OSMemTbl[0], sizeof(OSMemTbl)); /* Clear the memory partition table */ for (i = 0u; i < (OS_MAX_MEM_PART - 1u); i++) { /* Init. list of free memory partitions */ pmem = &OSMemTbl[i]; /* Point to memory control block (MCB) */ pmem->OSMemFreeList = (void *)&OSMemTbl[i + 1u]; /* Chain list of free partitions */ #if OS_MEM_NAME_EN > 0u pmem->OSMemName = (INT8U *)(void *)"?"; #endif } pmem = &OSMemTbl[i]; pmem->OSMemFreeList = (void *)0; /* Initialize last node */ #if OS_MEM_NAME_EN > 0u pmem->OSMemName = (INT8U *)(void *)"?"; #endif OSMemFreeList = &OSMemTbl[0]; /* Point to beginning of free list */ #endif } #endif /* OS_MEM_EN */ ~~~