ucos-ii 就续表和空链表 OS_TCBInit函数代码解析

 os_core.c中有函数

INT8U  OS_TCBInit (INT8U prio, OS_STK *ptos, OS_STK *pbos, INT16U id, INT32U stk_size, void *pext, INT16U opt){}

INT8U  OSTaskCreate (void (*task)(void *p_arg), void *p_arg, OS_STK *ptos, INT8U prio){}会

调用函数OS_TCBInit(prio, psp, (OiS_STK *)0, 0, 0, (void *)0, 0);

INT8U  OS_TCBInit (INT8U prio, OS_STK *ptos, OS_STK *pbos, INT16U id, INT32U stk_size, void *pext, INT16U opt)

{

      OS_TCB    *ptcb;

      OS_ENTER_CRITICAL();

      ptcb = OSTCBFreeList;                                  /* Get a free TCB from the free TCB list    */

      if (ptcb != (OS_TCB *)0)
     {

        OSTCBFreeList            = ptcb->OSTCBNext;        /* Update pointer to free TCB list        空任务链表更新 指向TCB的双向链接的后链接  我认为是FreeList 指向了原本那个TCB块的后面一个TCB块，即移除一个TCB给OSTCBList*/

        OS_EXIT_CRITICAL();

        ptcb->OSTCBStkPtr        = ptos;                   /* Load Stack pointer in TCB                */

        ptcb->OSTCBPrio          = prio;                   /* Load task priority into TCB              */

        ptcb->OSTCBStat          = OS_STAT_RDY;            /* Task is ready to run                     */

        ptcb->OSTCBStatPend      = OS_STAT_PEND_OK;        /* Clear pend status                        */

        ptcb->OSTCBDly           = 0;                      /* Task is not delayed                      */

        pext                     = pext;                   /* Prevent compiler warning if not used     */

        stk_size               = stk_size;

        pbos                    = pbos;

        opt                       = opt;

        id                         = id;

#if OS_LOWEST_PRIO <= 63

        ptcb->OSTCBY             = (INT8U)(prio >> 3);          /* Pre-compute X, Y, BitX and BitY     */

        ptcb->OSTCBX             = (INT8U)(prio & 0x07);

        ptcb->OSTCBBitY          = (INT8U)(1 << ptcb->OSTCBY);

        ptcb->OSTCBBitX          = (INT8U)(1 << ptcb->OSTCBX);

#else

        ptcb->OSTCBY             = (INT8U)((prio >> 4) & 0xFF); /* Pre-compute X, Y, BitX and BitY     */

        ptcb->OSTCBX             = (INT8U) (prio & 0x0F);

        ptcb->OSTCBBitY          = (INT16U)(1 << ptcb->OSTCBY);

        ptcb->OSTCBBitX          = (INT16U)(1 << ptcb->OSTCBX);

#endif

#if OS_TASK_PROFILE_EN > 0

        ptcb->OSTCBCtxSwCtr    = 0L;                       /* Initialize profiling variables           */

        ptcb->OSTCBCyclesStart = 0L;

        ptcb->OSTCBCyclesTot   = 0L;

        ptcb->OSTCBStkBase     = (OS_STK *)0;

        ptcb->OSTCBStkUsed     = 0L;

#endif

        OS_ENTER_CRITICAL();

        OSTCBPrioTbl[prio] = ptcb;                                 ///* Table of pointers to created TCBs        */

        ptcb->OSTCBNext    = OSTCBList;                    /* Link into TCB chain                      */将OSTCBList指向的那个TCB地址赋给ptcb->OSTCBNext（刚才从FreeList中移除的那个TCB的Next）

        ptcb->OSTCBPrev    = (OS_TCB *)0;        //如图prev前指针是指向NULL

        if (OSTCBList != (OS_TCB *)0)                    
        {

            OSTCBList->OSTCBPrev = ptcb;           //如下图 假如原先OSTCBList指向OSTCBPrio=1的那个TCB，即OSTCBList != (OS_TCB *)0    让OSTCBList->OSTCBPrev（OSTCBPrio=1的那个TCB的OSTCBPrev）=刚才从FreeList中移除的那个TCB

        }

        OSTCBList               = ptcb;         //OSTCBList由原来指向OSTCBPrio=1的那个TCB改为指向OSTCBPrio=3的那个TCB

        OSRdyGrp               |= ptcb->OSTCBBitY;         /* Make task ready to run                   */

        OSRdyTbl[ptcb->OSTCBY] |= ptcb->OSTCBBitX;

        OSTaskCtr++;                                       /* Increment the #tasks counter             */

        OS_EXIT_CRITICAL();

        return (OS_ERR_NONE);

    }

    OS_EXIT_CRITICAL();

    return (OS_ERR_TASK_NO_MORE_TCB);

}
 

 

红色代码还需细加斟酌。配合上篇日志。这两个链表的删除和添加。我还迷糊