*                                         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!)
*               OS_MEM_INVALID_PMEM  if you passed a NULL pointer for 'pmem'
*               OS_MEM_INVALID_PBLK  if you passed a NULL pointer for the block to release.
*********************************************************************************************************
*/
/*
*********************************************************************************************************
                                                        釋放一個內存塊
描述：返回一個內存塊到分割區中
參數；pmem：指向內存分割控制塊的指針
                pblk：指向將被釋放內存塊的指針
 返回：OS_NO_ERR：如果內存塊成功插入到分割區
                  OS_MEM_FULL：如果返回內存塊到一個已滿的內存分割區中
                  OS_MEM_INVALID_PMEM：如果你傳遞一個空指針到“pmem”
                  OS_MEM_INVALID_PBLK：如果傳一個空指針到將釋放的塊
備注：此函數并不知道內存塊是屬于哪個分區的，也就是說，如果用戶程序
從一個包含32B內存塊的分區中分配了一個內存塊，用完后千萬不要將一個包含
120B內存塊給返回來，因為如果下次一個程序申請120B內存時，只會得到32B
*********************************************************************************************************
*/



INT8U  OSMemPut (OS_MEM  *pmem, void *pblk)
{
#if OS_CRITICAL_METHOD == 3                      /* Allocate storage for CPU status register           */
    OS_CPU_SR  cpu_sr;
#endif    
    
    
#if OS_ARG_CHK_EN > 0
    if (pmem == (OS_MEM *)0) {                   /* Must point to a valid memory partition             */
        return (OS_MEM_INVALID_PMEM);//必須是可行的內存分割區
    }
    if (pblk == (void *)0) {                     /* Must release a valid block                         */
        return (OS_MEM_INVALID_PBLK);//必須釋放一個可行的內存塊
    }
#endif
    OS_ENTER_CRITICAL();
    if (pmem->OSMemNFree >= pmem->OSMemNBlks) {  /* Make sure all blocks not already returned          */
        OS_EXIT_CRITICAL();//檢查內存分區是否已滿，
        return (OS_MEM_FULL);//如果滿了，返回滿了
    }
    *(void **)pblk      = pmem->OSMemFreeList;   /* Insert released block into free block list         */
	//如果沒有滿，就插入
    pmem->OSMemFreeList = pblk;//這是什么意思，出現兩次了。它變成新的表頭？
    pmem->OSMemNFree++;                          /* One more memory block in this partition            */
	//塊數加一
    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            If no errors were found.
*               OS_MEM_INVALID_PMEM  if you passed a NULL pointer for 'pmem'
*               OS_MEM_INVALID_PDATA if you passed a NULL pointer for the block to release.
*********************************************************************************************************
*/
/*
*********************************************************************************************************
                                                查詢一個內存分區狀態
描述：查詢一億內存分割區的空內存塊和已用內存塊
參數：pmem：指向一個內存分割控制塊的指針
                 pdata:    將要包含內存分割區信息的結構指針
返回：OS_NO_ERR：沒有發現錯誤
                 OS_MEM_INVALID_PMEM ：如果傳送一個空指針給‘pmem’
                 OS_MEM_INVALID_PDATA:如果傳一個空指針到將釋放的塊
*********************************************************************************************************
*/



#if OS_MEM_QUERY_EN > 0
INT8U  OSMemQuery (OS_MEM *pmem, OS_MEM_DATA *pdata)
{
#if OS_CRITICAL_METHOD == 3                      /* Allocate storage for CPU status register           */
    OS_CPU_SR  cpu_sr;
#endif    
    
    
#if OS_ARG_CHK_EN > 0
    if (pmem == (OS_MEM *)0) {                   /* Must point to a valid memory partition             */
        return (OS_MEM_INVALID_PMEM);//必須是可行的分割區
    }
    if (pdata == (OS_MEM_DATA *)0) {             /* Must release a valid storage area for the data     */
        return (OS_MEM_INVALID_PDATA);//必須為數據釋放一個可行的存儲空間
    }//OS_MEM_DATA中存放了特定內存分區中內存塊的大小，可用內存塊數目和
    //已用內存塊數目等信息。
#endif
    OS_ENTER_CRITICAL();
    pdata->OSAddr     = pmem->OSMemAddr;//將指定內存分區的信息全部復制到指定變量的
    pdata->OSFreeList = pmem->OSMemFreeList;//相應區域，此過程中，中斷被關，防止在此過程中
    pdata->OSBlkSize  = pmem->OSMemBlkSize;//數據被改
    pdata->OSNBlks    = pmem->OSMemNBlks;
    pdata->OSNFree    = pmem->OSMemNFree;
    OS_EXIT_CRITICAL();
    pdata->OSNUsed    = pdata->OSNBlks - pdata->OSNFree;//計算已用塊
    return (OS_NO_ERR);
}
#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.
*********************************************************************************************************
*/
/*
*********************************************************************************************************
                                                            初始化內存分割區管理
描述：ucos內部調用，其它應用程序不能調用
參數：無
返回：元
備注：ucos內部調用，其它應用程序不能調用
*********************************************************************************************************
*/



void  OS_MemInit (void)
{
#if OS_MAX_MEM_PART == 1//分割區為一塊
    OSMemFreeList                = (OS_MEM *)&OSMemTbl[0]; /* Point to beginning of free list          */
//指向空閑列表開始的指針
    OSMemFreeList->OSMemFreeList = (void *)0;              /* Initialize last node                     */
//初始化最后結點？什么意思？它是指向空內存塊指針的
    OSMemFreeList->OSMemAddr     = (void *)0;              /* Store start address of memory partition  */
//保存內存分割區的開始地址
    OSMemFreeList->OSMemNFree    = 0;                      /* No free blocks                           */
//為零表明沒有空塊
    OSMemFreeList->OSMemNBlks    = 0;                      /* No blocks                                */
//分割區中沒有內存塊
    OSMemFreeList->OSMemBlkSize  = 0;                      /* Zero size                                */
//大小為零
#endif

#if OS_MAX_MEM_PART >= 2//如果分割區有兩塊以上
    OS_MEM  *pmem;//內存結構
    INT16U   i;


    pmem = (OS_MEM *)&OSMemTbl[0];                    /* Point to memory control block (MCB)           */
	//指向內存控制塊的指針
    for (i = 0; i < (OS_MAX_MEM_PART - 1); i++) {     /* Init. list of free memory partitions          */
		//對每一塊內存分割區進行初始化
        pmem->OSMemFreeList = (void *)&OSMemTbl[i+1]; /* Chain list of free partitions                 */
		//內存管理空間鏈表
        pmem->OSMemAddr     = (void *)0;              /* Store start address of memory partition       */
		//內存分割區存儲開始地址
        pmem->OSMemNFree    = 0;                      /* No free blocks                                */
		//無空閑塊
        pmem->OSMemNBlks    = 0;                      /* No blocks                                     */
		//無塊
        pmem->OSMemBlkSize  = 0;                      /* Zero size                                     */
		//大小為零
        pmem++;//內存控制塊加一？
    }
    pmem->OSMemFreeList = (void *)0;                  /* Initialize last node                          */
//初始化最后一個結點，空余內存塊列表指針
    pmem->OSMemAddr     = (void *)0;                  /* Store start address of memory partition       */
//開始地址
    pmem->OSMemNFree    = 0;                          /* No free blocks                                */
    pmem->OSMemNBlks    = 0;                          /* No blocks                                     */
    pmem->OSMemBlkSize  = 0;                          /* Zero size                                     */

    OSMemFreeList       = (OS_MEM *)&OSMemTbl[0];     /* Point to beginning of free list               */
	//空表開始指針
#endif
}
#endif                                           /* OS_MEM_EN                                          */