返回：無(wú)
備注：這個(gè)函數(shù)是ucosII內(nèi)部的，在應(yīng)用程序中不能調(diào)用
                 當(dāng)調(diào)度程序鎖定的話，重新調(diào)度將被禁止。（見OS_SchedLock()）

**************************************************************************************************
*/

void  OS_Sched (void)
{
#if OS_CRITICAL_METHOD == 3                            /* Allocate storage for CPU status register     */
    OS_CPU_SR  cpu_sr;//為CPU狀態(tài)寄存器分配存儲(chǔ)空間
#endif    
    INT8U      y;


    OS_ENTER_CRITICAL();//進(jìn)入臨界狀態(tài)
    if ((OSIntNesting == 0) && (OSLockNesting == 0)) { /* Sched. only if all ISRs done & not locked    */
		//如果中斷嵌套層為零，多任務(wù)處理鎖定嵌套層為零
		//即只有在所以ISR完成，且沒(méi)有鎖定的請(qǐng)況下調(diào)度
        y             = OSUnMapTbl[OSRdyGrp];          /* Get pointer to HPT ready to run              */
		//得到高優(yōu)先級(jí)就緒態(tài)的任務(wù)指針
        OSPrioHighRdy = (INT8U)((y << 3) + OSUnMapTbl[OSRdyTbl[y]]);
		//最高優(yōu)先級(jí)任務(wù)的優(yōu)先數(shù)算法，有時(shí)間要研究一下，現(xiàn)在看不懂
        if (OSPrioHighRdy != OSPrioCur) {              /* No Ctx Sw if current task is highest rdy     */
			//如果最高優(yōu)先級(jí)任務(wù)不是當(dāng)前任務(wù)
            OSTCBHighRdy = OSTCBPrioTbl[OSPrioHighRdy];//將最高優(yōu)先級(jí)任務(wù)調(diào)到即將運(yùn)行指針
            OSCtxSwCtr++;                              /* Increment context switch counter             */
			//上下文轉(zhuǎn)換數(shù)加一
            OS_TASK_SW();                              /* Perform a context switch                     */
            //運(yùn)行上下文轉(zhuǎn)換
        }
    }
    OS_EXIT_CRITICAL();//退出臨界狀態(tài)
}
/*$PAGE*/
/*
*********************************************************************************************************
*                                              IDLE TASK
*
* Description: This task is internal to uC/OS-II and executes whenever no other higher priority tasks
*              executes because they are ALL waiting for event(s) to occur.
*
* Arguments  : none
*
* Returns    : none
*
* Note(s)    : 1) OSTaskIdleHook() is called after the critical section to ensure that interrupts will be
*                 enabled for at least a few instructions.  On some processors (ex. Philips XA), enabling
*                 and then disabling interrupts didn't allow the processor enough time to have interrupts
*                 enabled before they were disabled again.  uC/OS-II would thus never recognize
*                 interrupts.
*              2) This hook has been added to allow you to do such things as STOP the CPU to conserve 
*                 power.
                                           空閑任務(wù)：
描述：這個(gè)任務(wù)是ucos內(nèi)部任務(wù)，由于其它任務(wù)都在等事件發(fā)生，
                沒(méi)有高優(yōu)先級(jí)任務(wù)運(yùn)行的時(shí)候它就運(yùn)行
參數(shù)：無(wú)
返回：無(wú)
備注：1、出臨界后要調(diào)用OSTaskIdleHook()保證中斷真正開啟。
                2、這個(gè)能加擴(kuò)展允許我們做一些事情，如：為了節(jié)能，讓CPU
                停止工作
*********************************************************************************************************
*/

void  OS_TaskIdle (void *pdata)
{
#if OS_CRITICAL_METHOD == 3                      /* Allocate storage for CPU status register           */
    OS_CPU_SR  cpu_sr;
#endif    
    
    
    pdata = pdata;                               /* Prevent compiler warning for not using 'pdata'     */
    for (;;) {
        OS_ENTER_CRITICAL();
        OSIdleCtr++;//加一前后中斷先關(guān)后開，是因?yàn)?位或者十六位處理器加一
        //需要多條指令，防止中斷打入。
        OS_EXIT_CRITICAL();
        OSTaskIdleHook();                        /* Call user definable HOOK                           */
    }
}
/*$PAGE*/
/*
*********************************************************************************************************
*                                            STATISTICS TASK
*
* Description: This task is internal to uC/OS-II and is used to compute some statistics about the
*              multitasking environment.  Specifically, OS_TaskStat() computes the CPU usage.
*              CPU usage is determined by:
*
*                                                     OSIdleCtr
*                 OSCPUUsage = 100 * (1 - ------------)     (units are in %)
*                                                    OSIdleCtrMax
*
* Arguments  : pdata     this pointer is not used at this time.
*
* Returns    : none
*
* Notes      : 1) This task runs at a priority level higher than the idle task.  In fact, it runs at the
*                 next higher priority, OS_IDLE_PRIO-1.
*              2) You can disable this task by setting the configuration #define OS_TASK_STAT_EN to 0.
*              3) We delay for 5 seconds in the beginning to allow the system to reach steady state and
*                 have all other tasks created before we do statistics.  You MUST have at least a delay
*                 of 2 seconds to allow for the system to establish the maximum value for the idle
*                 counter.
                                                         統(tǒng)計(jì)任務(wù)：
描述：作多任務(wù)處理的一些統(tǒng)計(jì)，一般計(jì)算CPU使用率，公式如下：
*                                                      OSIdleCtr
*                 OSCPUUsage = 100 * (1 - ------------)     (units are in %)
*                                                     OSIdleCtrMax
參數(shù)：pdata:暫時(shí)沒(méi)有用到
返回：無(wú)
備注：1、此任務(wù)優(yōu)先級(jí)只比idle高，實(shí)際上，它運(yùn)行在進(jìn)一步高的優(yōu)先
                       級(jí)上，OS_IDLE_PRIO-1
                2、通過(guò)設(shè)置OS_TASK_STAT_EN為零來(lái)禁止此任務(wù)
                3、我們延時(shí)5秒讓系統(tǒng)穩(wěn)定，統(tǒng)計(jì)前我們建立其它任務(wù)，
                      我們至少有兩秒去讓空閑任務(wù)建立最大值。

*********************************************************************************************************
*/

#if OS_TASK_STAT_EN > 0
void  OS_TaskStat (void *pdata)
{
#if OS_CRITICAL_METHOD == 3                      /* Allocate storage for CPU status register           */
    OS_CPU_SR  cpu_sr;
#endif    
    INT32U     run;
    INT32U     max;
    INT8S      usage;


    pdata = pdata;                               /* Prevent compiler warning for not using 'pdata'     */
    while (OSStatRdy == FALSE) {
        OSTimeDly(2 * OS_TICKS_PER_SEC);         /* Wait until statistic task is ready   */
		//延時(shí)兩秒OSIdleCr不會(huì)像沒(méi)有什么應(yīng)用任務(wù)運(yùn)行時(shí)那樣有那么多計(jì)數(shù)，
		//它最大計(jì)數(shù)值是OSStatInit()在初始化時(shí)，保存在空閑計(jì)數(shù)器最大值OSIdleCtr中的
    }
    max = OSIdleCtrMax / 100L;
    for (;;) {
        OS_ENTER_CRITICAL();
        OSIdleCtrRun = OSIdleCtr;                /* Obtain the of the idle counter for the past second */
        run          = OSIdleCtr;
        OSIdleCtr    = 0L;                       /* Reset the idle counter for the next second         */
		//清除，用于下一次測(cè)量
        OS_EXIT_CRITICAL();
        if (max > 0L) {
            usage = (INT8S)(100L - run / max);
            if (usage >= 0) {                    /* Make sure we don't have a negative percentage      */
                OSCPUUsage = usage;
            } else {
                OSCPUUsage = 0;
            }
        } else {
            OSCPUUsage = 0;
            max        = OSIdleCtrMax / 100L;
        }
        OSTaskStatHook();                        /* Invoke user definable hook           */
		//一旦完成，就調(diào)用外界接入函數(shù)OSTaskStatHook()，能使統(tǒng)計(jì)任務(wù)得到擴(kuò)展，
		//這樣用戶可以計(jì)算并顯示所有任務(wù)總執(zhí)行時(shí)間，每個(gè)任務(wù)執(zhí)行的百分比等。
        OSTimeDly(OS_TICKS_PER_SEC); /* Accumulate OSIdleCtr for the next second           */
		//為下一秒作準(zhǔn)備
    }
}
#endif
/*$PAGE*/
/*
*********************************************************************************************************
*                                            INITIALIZE TCB
*
* Description: This function is internal to uC/OS-II and is used to initialize a Task Control Block when
*              a task is created (see OSTaskCreate() and OSTaskCreateExt()).
*
* Arguments  : prio          is the priority of the task being created
*
*              ptos          is a pointer to the task's top-of-stack assuming that the CPU registers
*                            have been placed on the stack.  Note that the top-of-stack corresponds to a
*                            'high' memory location is OS_STK_GROWTH is set to 1 and a 'low' memory
*                            location if OS_STK_GROWTH is set to 0.  Note that stack growth is CPU
*                            specific.
*
*              pbos          is a pointer to the bottom of stack.  A NULL pointer is passed if called by
*                            'OSTaskCreate()'.
*
*              id            is the task's ID (0..65535)
*
*              stk_size      is the size of the stack (in 'stack units').  If the stack units are INT8Us
*                            then, 'stk_size' contains the number of bytes for the stack.  If the stack
*                            units are INT32Us then, the stack contains '4 * stk_size' bytes.  The stack
*                            units are established by the #define constant OS_STK which is CPU
*                            specific.  'stk_size' is 0 if called by 'OSTaskCreate()'.
*
*              pext          is a pointer to a user supplied memory area that is used to extend the task
*                            control block.  This allows you to store the contents of floating-point
*                            registers, MMU registers or anything else you could find useful during a
*                            context switch.  You can even assign a name to each task and store this name
*                            in this TCB extension.  A NULL pointer is passed if called by OSTaskCreate().
*
*              opt           options as passed to 'OSTaskCreateExt()' or,
*                            0 if called from 'OSTaskCreate()'.
*
* Returns    : OS_NO_ERR         if the call was successful
*              OS_NO_MORE_TCB    if there are no more free TCBs to be allocated and thus, the task cannot
*                                be created.
*
* Note       : This function is INTERNAL to uC/OS-II and your application should not call it.
*********************************************************************************************************
*/
/*
*******************************************************************************
                                           初始化任務(wù)控制塊
參數(shù)：prio：任務(wù)創(chuàng)建時(shí)的優(yōu)先級(jí)
      ptos:假定CPU寄存器放置于堆棧中指向堆棧棧頂?shù)闹羔槨ｍ敭?dāng)OS_STK_GROWTH為1時(shí)是寄存器的  

         高位、當(dāng)OS_STK_GROWTH為0時(shí)是寄存器的低位，堆棧增長(zhǎng)是CPU的特權(quán)。
      pbos：棧底指針。由OSTaskCreate()調(diào)用時(shí)傳入空指針。
      id： 任務(wù)的ID
      stk_size:堆棧大小。 當(dāng)堆棧單位是int8us時(shí)，堆棧大小包含堆棧數(shù)量個(gè)字節(jié)，當(dāng)堆棧單位是
               int32us時(shí)，堆棧大小包含“4*stk_size”個(gè)字節(jié)。堆棧單位由“#define constant
               OS_STK”建立，它是CPU特有。如果被OSTaskCreate()調(diào)用stk_size為0。
      pext：用戶提供存儲(chǔ)器空間的指針，用于任務(wù)控制塊。允許存儲(chǔ)浮點(diǎn)寄存器常量，MMU寄存器或
            者其它在內(nèi)容轉(zhuǎn)換時(shí)有用的東西。甚至在TCB擴(kuò)展中為每個(gè)任務(wù)指定一個(gè)名字存到這個(gè)名 字里面。
            當(dāng)被OSTaskCreate()調(diào)用的時(shí)候?yàn)榭罩羔槨?      opt ：傳到OSTaskCreateExt()時(shí)可以選擇，被OSTaskCreate()調(diào)用的時(shí)候?yàn)?。
返回：OS_NO_ERR ：如果調(diào)用成功。
      OS_NO_MORE_TCB：如果沒(méi)有多余TCB安排，所以任務(wù)不能被創(chuàng)建。
備注：這個(gè)函數(shù)對(duì)uC/OS-II來(lái)說(shuō)是內(nèi)部的，自己的應(yīng)用程序不能夠調(diào)用它。

*************************************************************************
*/

INT8U  OS_TCBInit (INT8U prio, OS_STK *ptos, OS_STK *pbos, INT16U id, INT32U stk_size, void *pext, INT16U opt)
{
#if OS_CRITICAL_METHOD == 3                                /* Allocate storage for CPU status register */
//為CPU狀態(tài)寄存器分配存儲(chǔ)空間
    OS_CPU_SR  cpu_sr;//#define OS_CPU_SR    unsigned int 
#endif    
    OS_TCB    *ptcb;//定義任務(wù)控制塊


    OS_ENTER_CRITICAL();//進(jìn)入臨界狀態(tài)
    ptcb = OSTCBFreeList;                                  /* Get a free TCB from the free TCB list    */
	  //從空TCB列表中得到一塊空TCB
    if (ptcb != (OS_TCB *)0) {//分配空TCB成功
        OSTCBFreeList        = ptcb->OSTCBNext;            /* Update pointer to free TCB list          */
		//更新空TCB列表，即減掉一塊
        OS_EXIT_CRITICAL();//退出臨界狀態(tài)
        ptcb->OSTCBStkPtr    = ptos;                       /* Load Stack pointer in TCB                */
		//裝載TCB中的堆棧指針
        ptcb->OSTCBPrio      = (INT8U)prio;                /* Load task priority into TCB              */
		//裝載TCB中任務(wù)優(yōu)先級(jí)
        ptcb->OSTCBStat      = OS_STAT_RDY;                /* Task is ready to run                     */
		//任務(wù)狀態(tài)設(shè)為就緒
        ptcb->OSTCBDly       = 0;                          /* Task is not delayed                      */
		//任務(wù)不延時(shí)

#if OS_TASK_CREATE_EXT_EN > 0//如果能使
        ptcb->OSTCBExtPtr    = pext;                       /* Store pointer to TCB extension           */
        //存儲(chǔ)TCB擴(kuò)展指針
        ptcb->OSTCBStkSize   = stk_size;                   /* Store stack size */
		//存儲(chǔ)堆棧大小
        ptcb->OSTCBStkBottom = pbos;                       /* Store pointer to bottom of stack         */
		//存儲(chǔ)棧底指針
        ptcb->OSTCBOpt       = opt;                        /* Store task options                       */
		//存儲(chǔ)任務(wù)選項(xiàng)
        ptcb->OSTCBId        = id;                         /* Store task ID                            */
		//保存任務(wù)ID
#else//如果不能使
        pext                 = pext;                       /* Prevent compiler warning if not used     */
        stk_size             = stk_size;
        pbos