uC/OS-II内存管理之OSMemCreate()代码可读性的一点改进

来源：互联网发布：it全称编辑：程序博客网时间：2024/05/16 11:20

个人感觉uC/OS-II内存管理之OSMemCreate()，在创建空余内存块链表时，可读性不好。

该函数源代码：

OS_MEM  *OSMemCreate (void *addr, INT32U nblks, INT32U blksize, INT8U *err){#if OS_CRITICAL_METHOD == 3                           /* Allocate storage for CPU status register      */    OS_CPU_SR  cpu_sr;#endif        OS_MEM    *pmem;    INT8U     *pblk;    void     **plink;    INT32U     i;#if OS_ARG_CHK_EN > 0    if (addr == (void *)0) {                          /* Must pass a valid address for the memory part. */        *err = OS_MEM_INVALID_ADDR;        return ((OS_MEM *)0);    }    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);    }#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             */        *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              */    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        */    *err                = OS_NO_ERR;    return (pmem);}

创建空余内存块链表时

原先是，pblk在循环开始前就指向第二个内存块，只需N-1次完成链表。

    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              */

现修改成循环前plink和pblk都指首地址，也就是第一个内存块的地址，有N个内存块就循环N次。这样感觉比较好理解。

    /* plink 和 pblk 进行循环前，都指向addr */    plink = (void **)addr;                            /* Create linked list of free memory blocks      */    pblk  = (INT8U *)addr;                               for (i = 0; i < nblks; i++) {                     /* N个内存块就循环N次 */        pblk   = pblk + blksize;        *plink = (void *)pblk;        plink  = (void **)pblk;    }    *plink              = (void *)0;                  /* Last memory block points to NULL              */