ucos源码求大神帮我解析下~~~

liuchang---

ucos源码求大神帮我解析下~~~ [复制链接]

小弟初学ucos,如下为ucos内存管理单元中一个函数---创建动态内存分配区函数,后面的注释是小弟自己加的,有的地方理解不通,恳请大神能帮我把这段源码给重新注释下,万分感谢(最好能把我理解有问题的地方给修改下)~~~
OS_MEM  *OSMemCreate (
                                                               /*创建动态内存分区*/
   void *addr,    /*内存分区的起始地址*/
   INT32U nblks,  /*内存分区中内存块的数目*/
   INT32U blksize,/*内存块的大小*/
   INT8U *err    /*错误信息*/
   )
{
OS_MEM *pmem;
INT8U    *pblk;
void    **plink;
INT32U    i;
#if OS_CRITICAL_METHOD == 3                         /* Allocate storage for CPU status register    */
OS_CPU_SR  cpu_sr = 0;
#endif

#if OS_ARG_CHK_EN > 0
if (err == (INT8U *)0) {                         /* Validate 'err'错误类型的指针不能为空*/
      return ((OS_MEM *)0);
}
if (addr == (void *)0) {                         /* Must pass a valid address for the memory part.内存分区的起始地址必须有效*/
      *err = OS_MEM_INVALID_ADDR;
      return ((OS_MEM *)0);
}
if (nblks < 2) {                               /* Must have at least 2 blocks per partition至少需要2个内存控制块*/
      *err = OS_MEM_INVALID_BLKS;
      return ((OS_MEM *)0);
}
if (blksize < sizeof(void *)) {                /* Must contain space for at least a pointer至少要包含一个指针的内存空间*/
      *err = OS_MEM_INVALID_SIZE;
      return ((OS_MEM *)0);
}
#endif
OS_ENTER_CRITICAL();
pmem = OSMemFreeList;                                     /*这里OSMemFreeList可理解为链表头???*/
if (OSMemFreeList != (OS_MEM *)0)                         /*该链表非指向空*/
{
      OSMemFreeList = (OS_MEM *)OSMemFreeList->OSMemFreeList;/*这句话该如何理解?指向链表的下一个节点???*/
}
OS_EXIT_CRITICAL();
if (pmem == (OS_MEM *)0)                                  /*如果该链表指向空*/
{
      *err = OS_MEM_INVALID_PART;
      return ((OS_MEM *)0);
}
plink = (void **)addr;                         /* Create linked list of free memory blocks    */
pblk  = (INT8U *)((INT32U)addr + blksize);       /*pblk是一个指针,该指针指向每个内存块的首地址*/
for (i = 0; i < (nblks - 1); i++)
{
   *plink = (void *)pblk;                      /* Save pointer to NEXT block in CURRENT block */
      plink = (void **)pblk;                      /* plink是内存块首地址的指针                */
      pblk  = (INT8U *)((INT32U)pblk + blksize); /* Point to the FOLLOWING block                */
}
*plink             = (void *)0;                /* 最后一个内存块的指针域为空             */
pmem->OSMemAddr    = addr;                      /* 内存分区的起始地址是addr    */
pmem->OSMemFreeList = addr;                      /* 第一个内存控制块的起始地址也是addr */
pmem->OSMemNFree = nblks;                   /* 内存分区内当前可用内存块的数目       */
pmem->OSMemNBlks = nblks;                   /*内存区内总共有的内存块的数目*/
pmem->OSMemBlkSize  = blksize;                   /* 每个内存块的大小*/
*err             = OS_NO_ERR;
return (pmem);
}