ucos-ii 嵌入式系统 就绪表和空链表

ucos_ii.h中：

#if OS_LOWEST_PRIO <= 63

OS_EXT  INT8U             OSRdyGrp;                        /* Ready list group                         */

OS_EXT  INT8U             OSRdyTbl[OS_RDY_TBL_SIZE];       /* Table of tasks which are ready to run    */

#else

OS_EXT  INT16U            OSRdyGrp;                        /* Ready list group                         */

OS_EXT  INT16U            OSRdyTbl[OS_RDY_TBL_SIZE];       /* Table of tasks which are ready to run    */

#endif

OS_EXT  OS_TCB           *OSTCBCur;                        /* Pointer to currently running TCB         */

OS_EXT  OS_TCB           *OSTCBFreeList;                   /* Pointer to list of free TCBs             */

OS_EXT  OS_TCB           *OSTCBHighRdy;                    /* Pointer to highest priority TCB R-to-R   */

OS_EXT  OS_TCB           *OSTCBList;                       /* Pointer to doubly linked list of TCBs    */

OS_EXT  OS_TCB           *OSTCBPrioTbl[OS_LOWEST_PRIO + 1];/* Table of pointers to created TCBs        */

OS_EXT  OS_TCB            OSTCBTbl[OS_MAX_TASKS + OS_N_SYS_TASKS];   /* Table of TCBs                  */
































 
//os_core.c
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;
    if (ptcb != (OS_TCB *)0) {
        OSTCBFreeList        = ptcb->OSTCBNext;            /* Update pointer to free TCB list          */
        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;
#if OS_LOWEST_PRIO <= 63
        ptcb->OSTCBY         = (INT8U)(prio >> 3);         /* Pre-compute X, Y, BitX and BitY          */
        ptcb->OSTCBBitY      = (INT8U)(1 << ptcb->OSTCBY);
        ptcb->OSTCBX         = (INT8U)(prio & 0x07);
        ptcb->OSTCBBitX      = (INT8U)(1 << ptcb->OSTCBX);
#else
        ptcb->OSTCBY         = (INT8U)((prio >> 4) & 0xFF);/* Pre-compute X, Y, BitX and BitY          */
        ptcb->OSTCBBitY      = (INT16U)(1 << ptcb->OSTCBY);
        ptcb->OSTCBX         = (INT8U)(prio & 0x0F);
        ptcb->OSTCBBitX      = (INT16U)(1 << ptcb->OSTCBX);
#endif

       

       

        OS_ENTER_CRITICAL();
        OSTCBPrioTbl[prio] = ptcb;
        ptcb->OSTCBNext    = OSTCBList;                    /* Link into TCB chain                      */    
                                                                            //ptcb->OSTCBNext  指向 OSTCBList所指向的节点。
        ptcb->OSTCBPrev    = (OS_TCB *)0;       //ptcb->OSTCBPrev指向空，图中可看出。
        if (OSTCBList != (OS_TCB *)0) {             
            OSTCBList->OSTCBPrev = ptcb;              //OSTCBList所指向的节点的OSTCBPrev 指向新节点ptcb
        }
        OSTCBList               = ptcb;   //OSTCBList 链表头指向新节点ptcb。
        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);
}