OS_SchedNew(void)找到將要運(yùn)行的最高優(yōu)先級(jí)任務(wù)函數(shù)

和任務(wù)調(diào)度函數(shù)OS_Sched(void)：

/* ********************************************************************************************************* * FIND HIGHEST PRIORITY TASK READY TO RUN * 找到將要運(yùn)行的最高優(yōu)先級(jí)任務(wù) * Description: This function is called by other uC/OS-II services to determine the highest priority task * that is ready to run. The global variable 'OSPrioHighRdy' is changed accordingly. *描述： 該功能被其他服務(wù)調(diào)用，用來(lái)決定將要運(yùn)行的最高優(yōu)先級(jí)任務(wù)是什么。全局變量OSPrioHighRdy相應(yīng)改變。 * Arguments : none *參數(shù)：無(wú) * Returns : none *返回值：無(wú) * Notes : 1) This function is INTERNAL to uC/OS-II and your application should not call it. * 2) Interrupts are assumed to be disabled when this function is called.注釋： 1）該功能是內(nèi)部函數(shù)，你的應(yīng)用程序不能調(diào)用。2）當(dāng)這個(gè)功能被調(diào)用的時(shí)候不能被中斷（原子函數(shù)） ********************************************************************************************************* */static void OS_SchedNew(void) /*找到將要被調(diào)度的任務(wù)*/ { #if OS_LOWEST_PRIO <= 63u /*優(yōu)先級(jí)<=63，支持64位任務(wù)*/INT8U y;y = OSUnMapTbl[OSRdyGrp]; OSPrioHighRdy = (INT8U)((y << 3u) + OSUnMapTbl[OSRdyTbl[y]]);/*計(jì)算最高優(yōu)先級(jí)任務(wù)的優(yōu)先級(jí)*/ #else /* We support up to 256 tasks支持256個(gè)任務(wù) */INT8U y;OS_PRIO *ptbl; /*ptb1是指向事件控制塊的指針*/if ((OSRdyGrp & 0xFFu) != 0u) /*如果就緒組不為0*/{ y = OSUnMapTbl[OSRdyGrp & 0xFFu]; /*y為在表中查到的數(shù)*/}else {y = OSUnMapTbl[(OS_PRIO)(OSRdyGrp >> 8u) & 0xFFu] + 8u;/*將y置為8*/}ptbl = &OSRdyTbl[y];if ((*ptbl & 0xFFu) != 0u) /*計(jì)算出優(yōu)先級(jí)*/{OSPrioHighRdy = (INT8U)((y << 4u) + OSUnMapTbl[(*ptbl & 0xFFu)]);}else {OSPrioHighRdy = (INT8U)((y << 4u) + OSUnMapTbl[(OS_PRIO)(*ptbl >> 8u) & 0xFFu] + 8u);} #endif }

/*$PAGE*/ /*2018/2/8 ********************************************************************************************************* * SCHEDULER * 調(diào)度 * Description: This function is called by other uC/OS-II services to determine whether a new, high * priority task has been made ready to run. This function is invoked by TASK level code * and is not used to reschedule tasks from ISRs (see OSIntExit() for ISR rescheduling). *描述：該功能被其他服務(wù)調(diào)用，用來(lái)決定是否一個(gè)新的、高優(yōu)先級(jí)任務(wù)已經(jīng)準(zhǔn)備好運(yùn)行了。任務(wù)級(jí)的調(diào)度是由函數(shù)OSSched()完成的。中斷級(jí)的調(diào)度是由另一個(gè)函數(shù)OSIntExt()完成的). * Arguments : none *參數(shù)：無(wú) * Returns : none *返回值：無(wú) * Notes : 1) This function is INTERNAL to uC/OS-II and your application should not call it. * 2) Rescheduling is prevented when the scheduler is locked (see OS_SchedLock()) 注釋： 1）該功能為內(nèi)部函數(shù)，你的應(yīng)用程序不能調(diào)用2） 給調(diào)度器上鎖用于禁止任務(wù)調(diào)度 (查看 OSSchedLock()函數(shù)) ********************************************************************************************************* */void OS_Sched(void) /*任務(wù)調(diào)度函數(shù)*/ { #if OS_CRITICAL_METHOD == 3u /*中斷函數(shù)被設(shè)定為模式3*/OS_CPU_SR cpu_sr = 0u; #endifOS_ENTER_CRITICAL(); /*關(guān)中斷*/if (OSIntNesting == 0u) { /*如果所有的中斷都完成了 */if (OSLockNesting == 0u) { /* 并且調(diào)度器沒(méi)有被鎖 */OS_SchedNew(); /*找到要運(yùn)行的任務(wù)*/OSTCBHighRdy = OSTCBPrioTbl[OSPrioHighRdy]; /*為實(shí)現(xiàn)任務(wù)切換，OSTCBHighRdy必須指向優(yōu)先級(jí)最高的那個(gè)任務(wù)控制塊OS_TCB，這是通過(guò)將以O(shè)SPrioHighRdy為下標(biāo)的OSTCBPrioTbl[]數(shù)組中的那個(gè)元素賦給OSTCBHighRdy來(lái)實(shí)現(xiàn)的*/if (OSPrioHighRdy != OSPrioCur) { /*找到最高優(yōu)先級(jí)任務(wù)后，函數(shù)檢查這個(gè)優(yōu)先級(jí)最高的任務(wù)是否是當(dāng)前正在運(yùn)行的任務(wù)，以避免不必要的任務(wù)調(diào)度，多花時(shí)間*/#if OS_TASK_PROFILE_EN > 0uOSTCBHighRdy->OSTCBCtxSwCtr++; /* Inc. # of context switches to this task */#endifOSCtxSwCtr++; /*任務(wù)切換計(jì)數(shù)值加1，統(tǒng)計(jì)切換次數(shù) */OS_TASK_SW(); /*進(jìn)行實(shí)際的任務(wù)交換 */}}}OS_EXIT_CRITICAL(); /*開(kāi)中斷*/ }

這兩個(gè)函數(shù)中讓人費(fèi)解的還是計(jì)算優(yōu)先級(jí)那一塊。回頭看了（9）中介紹的有關(guān)知識(shí)，感覺(jué)描述的還是不夠清楚。有時(shí)間重新梳理一下，盡量描述詳盡。

?OS_StrLen(INT8U *psrc)確定一個(gè)ASCII字符串的長(zhǎng)度的函數(shù)：

/*$PAGE*/ /*2018/2/8 ********************************************************************************************************* * DETERMINE THE LENGTH OF AN ASCII STRING * 確定一個(gè)ASCII字符串的長(zhǎng)度 * Description: This function is called by other uC/OS-II services to determine the size of an ASCII string * (excluding the NUL character). *描述：該功能被其他服務(wù)調(diào)用，用來(lái)確定一個(gè)ASCII字符串的長(zhǎng)度，包括最后的null字符。 * Arguments : psrc is a pointer to the string for which we need to know the size. *參數(shù)： --psrc指向字符串 * Returns : The size of the string (excluding the NUL terminating character) *返回值： 返回字符串的大小（包括最后空終止字符）。 * Notes : 1) This function is INTERNAL to uC/OS-II and your application should not call it. * 2) The string to check must be less than 255 characters long.注釋： 1）該功能是內(nèi)部函數(shù)，你的應(yīng)用程序不能調(diào)用它；2）要確定的字符串必須小于255字符。 ********************************************************************************************************* */#if (OS_EVENT_NAME_EN > 0u) || (OS_FLAG_NAME_EN > 0u) || (OS_MEM_NAME_EN > 0u) || (OS_TASK_NAME_EN > 0u) || (OS_TMR_CFG_NAME_EN > 0u) INT8U OS_StrLen(INT8U *psrc) {INT8U len;len = 0u; /*剛開(kāi)始初始化len為0*/while (*psrc != OS_ASCII_NUL) /*字符串沒(méi)有到結(jié)尾*/{psrc++; /*指針后移*/len++; /*長(zhǎng)度加1*/} return (len); /*返回長(zhǎng)度len*/ } #endif

這個(gè)函數(shù)不需要多說(shuō)。

?OS_TaskIdle(void *p_arg)空閑任務(wù)函數(shù)：

/*$PAGE*/ /*2018/2/8 ********************************************************************************************************* * IDLE TASK * 空閑任務(wù) * 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. *描述： 這個(gè)函數(shù)是uC/OS-II內(nèi)部函數(shù)，uC/OS-II總要建立一個(gè)空閑任務(wù)，這個(gè)任務(wù)在沒(méi)有其它任務(wù)進(jìn)入就緒態(tài)時(shí)投入運(yùn)行。 這個(gè)空閑任務(wù)永遠(yuǎn)設(shè)為最低優(yōu)先級(jí)，即OS_LOWEST_PRIO.空閑任務(wù)不可能被應(yīng)用軟件刪除。 * Arguments : none *參數(shù):無(wú) * Returns : none *返回值：無(wú) * 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.注釋：1）OSTaskIdleHook（）......（自行百度）2）讓CPU執(zhí)行STOP指令，從而進(jìn)入低功耗模式，當(dāng)應(yīng)用系統(tǒng)由電池供電時(shí)，這種方式特別有用。 ********************************************************************************************************* */void OS_TaskIdle(void *p_arg) { #if OS_CRITICAL_METHOD == 3u /* 中斷號(hào)設(shè)置為3 */OS_CPU_SR cpu_sr = 0u; #endifp_arg = p_arg; /*賦值給自己本身，防止編譯器出現(xiàn)錯(cuò)誤*/for (;;) {OS_ENTER_CRITICAL(); /*關(guān)中斷*/OSIdleCtr++; /*空閑任務(wù)數(shù)量加1*/OS_EXIT_CRITICAL(); /*開(kāi)中斷*/OSTaskIdleHook(); /* 調(diào)用用戶自定義的鉤子函數(shù) */} }

空閑任務(wù)函數(shù)主要是統(tǒng)計(jì)空閑任務(wù)數(shù)量，調(diào)用用戶自定義的鉤子函數(shù)。

OS_TaskStatStkChk(void)檢查所有的任務(wù)堆棧函數(shù)：

/*$PAGE*/ /*2018/2/9 ********************************************************************************************************* * CHECK ALL TASK STACKS * 檢查所有的任務(wù)堆棧 * Description: This function is called by OS_TaskStat() to check the stacks of each active task. *描述：該功能被OS_TaskStat（）統(tǒng)計(jì)任務(wù)調(diào)用，用來(lái)家產(chǎn)每個(gè)活躍的任務(wù)的堆棧 * Arguments : none *參數(shù)：無(wú) * Returns : none 返回值：無(wú) ********************************************************************************************************* */#if (OS_TASK_STAT_STK_CHK_EN > 0u) && (OS_TASK_CREATE_EXT_EN > 0u) void OS_TaskStatStkChk(void) {OS_TCB *ptcb;OS_STK_DATA stk_data;INT8U err;INT8U prio;for (prio = 0u; prio <= OS_TASK_IDLE_PRIO; prio++) {err = OSTaskStkChk(prio, &stk_data); /*檢測(cè)任務(wù)是否有問(wèn)題*/if (err == OS_ERR_NONE) /*如果沒(méi)問(wèn)題*/{ptcb = OSTCBPrioTbl[prio]; /*從優(yōu)先級(jí)為0的任務(wù)開(kāi)始檢查*/if (ptcb != (OS_TCB *)0) { if (ptcb != OS_TCB_RESERVED) /*確定任務(wù)是有效任務(wù)*/{ #if OS_TASK_PROFILE_EN > 0u#if OS_STK_GROWTH == 1u/*向下增長(zhǎng)方式，就是從高地址向低地址增長(zhǎng)，棧頂在高地址端。*/ptcb->OSTCBStkBase = ptcb->OSTCBStkBottom + ptcb->OSTCBStkSize;/*改變棧底指針位置*/#elseptcb->OSTCBStkBase = ptcb->OSTCBStkBottom - ptcb->OSTCBStkSize;/*改變棧底指針位置*/#endifptcb->OSTCBStkUsed = stk_data.OSUsed; /* 存儲(chǔ)已經(jīng)使用的字節(jié)數(shù)*/#endif}}}} } #endif上面的：

OS_STK_DATA stk_data;這個(gè)語(yǔ)句中，解釋一下OS_STK_DATA結(jié)構(gòu)體，方便大家理解：

/* *2018/1/30 ********************************************************************************************************* * TASK STACK DATA * 任務(wù)堆棧數(shù)據(jù) ********************************************************************************************************* */#if OS_TASK_CREATE_EXT_EN > 0u typedef struct os_stk_data {INT32U OSFree; /* Number of free bytes on the stack 堆棧中未使用的字節(jié)數(shù) */INT32U OSUsed; /* Number of bytes used on the stack 堆棧中已使用的字節(jié)數(shù) */ } OS_STK_DATA; #endif

?OS_TaskStat(void *p_arg)統(tǒng)計(jì)任務(wù)函數(shù)：

/*$PAGE*/ /*2018/2/8 ********************************************************************************************************* * STATISTICS TASK * 統(tǒng)計(jì)任務(wù) * 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: *描述：這個(gè)任務(wù)是uc/os-ii內(nèi)部任務(wù)，并且被用來(lái)計(jì)算一些關(guān)于多任務(wù)環(huán)境的統(tǒng)計(jì)數(shù)據(jù)。最關(guān)鍵的是用OS_TaskStat（）函數(shù)計(jì)算CPU的使用率 * OSIdleCtr * OSCPUUsage = 100 * (1 - ------------) (units are in %) * OSIdleCtrMax * cpu的使用率=100*（1-空閑任務(wù)數(shù)/設(shè)定的空閑任務(wù)總數(shù)） * Arguments : parg this pointer is not used at this time. *參數(shù)： --parg：這個(gè)時(shí)候不使用parg * Returns : none *返回值： 無(wú) * Notes : 1) This task runs at a priority level higher than the idle task. In fact, it runs at the * next higher priority, OS_TASK_IDLE_PRIO-1. * 2) You can disable this task by setting the configuration #define OS_TASK_STAT_EN to 0. * 3) You MUST have at least a delay of 2/10 seconds to allow for the system to establish the * maximum value for the idle counter.注釋： 1） uC/OS-II已經(jīng)將空閑任務(wù)的優(yōu)先級(jí)設(shè)為最低，即OS_LOWEST_PR10，統(tǒng)計(jì)任務(wù)的優(yōu)先級(jí)設(shè)為次低，OS_LOWEST_PR10-1.2）你可以通過(guò)設(shè)置配置禁用該任務(wù) #define OS_TASK_STAT_EN to 0.3）你必須有至少0.2s（2個(gè)時(shí)鐘節(jié)拍）的延遲來(lái)使系統(tǒng)能夠?yàn)榭臻e任務(wù)計(jì)數(shù)器設(shè)置最大值 ********************************************************************************************************* */#if OS_TASK_STAT_EN > 0u void OS_TaskStat(void *p_arg) /*任務(wù)統(tǒng)計(jì)函數(shù)*/ { #if OS_CRITICAL_METHOD == 3u /*將中斷類型設(shè)置為3*/OS_CPU_SR cpu_sr = 0u; #endifp_arg = p_arg; /*自己給自己賦值，防止編譯出現(xiàn)錯(cuò)誤*/while (OSStatRdy == OS_FALSE) /*如果統(tǒng)計(jì)任務(wù)狀態(tài)不是就緒的，通過(guò)延遲函數(shù)OSTimeDly（）等待*/{ OSTimeDly(2u * OS_TICKS_PER_SEC / 10u); /* Wait until statistic task is ready*/}OSIdleCtrMax /= 100uL; /*將最大空閑計(jì)數(shù)值對(duì)100求整*/if (OSIdleCtrMax == 0uL) /*如果最大空閑計(jì)數(shù)值為0*/{OSCPUUsage = 0u; /*CPU使用率為0*/#if OS_TASK_SUSPEND_EN > 0u /*如果允許任務(wù)掛起*/(void)OSTaskSuspend(OS_PRIO_SELF);/*調(diào)用任務(wù)掛起函數(shù)（參數(shù)為自身的優(yōu)先級(jí)）*/#else /*不允許任務(wù)掛起*/for (;;) {OSTimeDly(OS_TICKS_PER_SEC); /*就通過(guò)延遲函數(shù)進(jìn)行等待*/}#endif}for (;;) {OS_ENTER_CRITICAL(); /*關(guān)中斷*/OSIdleCtrRun = OSIdleCtr; /*將此時(shí)統(tǒng)計(jì)的空閑計(jì)數(shù)值賦給OSIdleCtrRun這個(gè)臨時(shí)變量*/OSIdleCtr = 0uL; /*將OSIdleCtr重新設(shè)置為0，然后進(jìn)行下一秒鐘的計(jì)數(shù)*/OS_EXIT_CRITICAL(); /*開(kāi)中斷*/OSCPUUsage = (INT8U)(100uL - OSIdleCtrRun / OSIdleCtrMax); /*計(jì)算CPU的使用率*/OSTaskStatHook(); /*執(zhí)行用戶自定義的鉤子函數(shù)*/#if (OS_TASK_STAT_STK_CHK_EN > 0u) && (OS_TASK_CREATE_EXT_EN > 0u)OS_TaskStatStkChk(); /*任務(wù)堆棧檢測(cè)*/#endifOSTimeDly(OS_TICKS_PER_SEC / 10u); /*調(diào)用延遲函數(shù)OSTimeDly()將自身延時(shí)1個(gè)時(shí)鐘節(jié)拍以停止自身的運(yùn)行*/} } #endif

在這個(gè)函數(shù)中想解釋一下幾點(diǎn)：

1.任務(wù)統(tǒng)計(jì)函數(shù)中最主要的幾個(gè)語(yǔ)句是：

OSIdleCtrMax /= 100uL; /*將最大空閑計(jì)數(shù)值對(duì)100求整*/ OSIdleCtrRun = OSIdleCtr; /*將此時(shí)統(tǒng)計(jì)的空閑計(jì)數(shù)值賦給OSIdleCtrRun這個(gè)臨時(shí)變量*/ OSIdleCtr = 0uL; /*將OSIdleCtr重新設(shè)置為0，然后進(jìn)行下一秒鐘的計(jì)數(shù)*/ OSCPUUsage = (INT8U)(100uL - OSIdleCtrRun / OSIdleCtrMax); /*計(jì)算CPU的使用率*/

2.在這個(gè)函數(shù)中：解釋一下下面這個(gè)語(yǔ)句：

OSIdleCtrMax /= 100uL; /*將最大空閑計(jì)數(shù)值對(duì)100求整*/

大家可能看到這個(gè)語(yǔ)句時(shí)和我有著同樣的疑問(wèn)：為什么要對(duì)100取整？有什么必要性？

?這里將最大值除以100是為了之后的計(jì)算。若是不除100，根據(jù)前面提到的公式來(lái)的話，?OSIdleCtr / OSIdleCtrMax這里我們希望得到的是一個(gè)浮點(diǎn)數(shù)，也就是一個(gè)小于1的小數(shù)，但是因?yàn)镺SIdleCtr、OSIdleCtrMax 都是整數(shù)，且OSIdleCtr < OSIdleCtrMax,則兩個(gè)數(shù)相除就必定為0，則OSCPUUsage 始終會(huì)等于100。所以先OSIdleCtrMax /100，然后再OSIdleCtrRun / OSIdleCtrMax，這個(gè)結(jié)果就不會(huì)是一個(gè)小于0的數(shù)，這個(gè)時(shí)候就不會(huì)出現(xiàn)始終等于0的情況 。同時(shí)在算數(shù)邏輯上100 - OSIdleCtrRun / OSIdleCtrMax=100 -OSIdleCtrRun *100/ OSIdleCtrMax = 100(1 -OSIdleCtrRun / OSIdleCtrMax )。這樣計(jì)算能夠接近數(shù)學(xué)運(yùn)算的結(jié)果。

3.第三個(gè)關(guān)于這個(gè)函數(shù)的疑問(wèn)是：在for循環(huán)最后的一行語(yǔ)句：

OSTimeDly(OS_TICKS_PER_SEC / 10u); /*調(diào)用延遲函數(shù)OSTimeDly()將自身延時(shí)1個(gè)時(shí)鐘節(jié)拍以停止自身的運(yùn)行*/

我們知道這個(gè)語(yǔ)句是延遲函數(shù)。但是這里為什么要用呢？

實(shí)際上，OSTimeDly（）函數(shù)可以看作一個(gè)延時(shí)函數(shù)，但是它真正的內(nèi)涵是將CPU讓給其他的任務(wù)。將自身的任務(wù)延時(shí)，在OSTimeDly（Ticks）這段時(shí)間內(nèi)調(diào)用OS_Sched（）函數(shù)找出任務(wù)就緒列表中優(yōu)先級(jí)最高的任務(wù)并將當(dāng)前CPU切換到該任務(wù)。

關(guān)于這個(gè)函數(shù)就介紹到這里。

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

初始化TCB函數(shù)：

/*$PAGE*/ /*2018/2/9 ********************************************************************************************************* * INITIALIZE TCB * 初始化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()). *描述：該功能是內(nèi)部函數(shù)，當(dāng)有任務(wù)被創(chuàng)建時(shí)（詳情見(jiàn)OSTaskCreate（）函數(shù)和OSTaskCreateExt（）函數(shù)），該函數(shù)被用來(lái)初始化任務(wù)控制塊， * Arguments : prio is the priority of the task being created *參數(shù)： --prio是被創(chuàng)建任務(wù)的優(yōu)先級(jí) * 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. * --ptos：假設(shè)CPU寄存器被堆棧占用，ptos就是指向棧頂?shù)闹羔槨Ｗ⒁?#xff1a;如果內(nèi)存增長(zhǎng)方式被設(shè)定為1（從高地址到低地址），那么ptos（棧頂）指向的是高地址；相反，如果增長(zhǎng)方式被設(shè)定為0（從低地址到高地址），那么ptos（棧頂）指向的是低地址。具體是什么增長(zhǎng)方式取決于不同的CPU * pbos is a pointer to the bottom of stack. A NULL pointer is passed if called by * 'OSTaskCreate()'. * --pbos：指向棧底的指針。如果是使用OSTaskCreate（）創(chuàng)建任務(wù)，pbos被設(shè)定為null空。 * id is the task's ID (0..65535) * --id是棧的ID號(hào) * 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()'. * --stk_size：是棧的大小（或者準(zhǔn)確講師棧單元的大小）。如果棧單元是8位的，stk_size值得就是8位可以表示的字節(jié)大小（2的8次方字節(jié)）。如果棧單元室32位的，這個(gè)棧就有4*stk_size字節(jié)這么大。棧單元是通過(guò) #define constant OS_STK來(lái)定義的。與CPU類型相關(guān) * 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(). * --pext擴(kuò)展指針：指向用戶可使用的內(nèi)存單元，該內(nèi)存單元是為了擴(kuò)大任務(wù)控制塊。這樣可以存儲(chǔ)浮點(diǎn)數(shù)寄存器、MMU寄存器或者其他在上下文交換時(shí)可用的寄存器中的內(nèi)容。甚至可以設(shè)定每個(gè)任務(wù)的名稱，并將該名稱存儲(chǔ)在TCB擴(kuò)展中。 * opt options as passed to 'OSTaskCreateExt()' or, * 0 if called from 'OSTaskCreate()'. * --opt：如果是OSTaskCreateExt（）調(diào)用，代表OS_TCB的選擇項(xiàng)，如果是OSTaskCreate（）調(diào)用，opt為0 * Returns : OS_ERR_NONE if the call was successful * OS_ERR_TASK_NO_MORE_TCB if there are no more free TCBs to be allocated and thus, the task cannot * be created. *返回值：OS_ERR_NONE：調(diào)用成功返回該值OS_ERR_TASK_NO_MORE_TCB：如果沒(méi)有空閑的TCB了，任務(wù)不能被創(chuàng)建，返回該值 * Note : This function is INTERNAL to uC/OS-II and your application should not call it. 注釋： 該功能是內(nèi)部函數(shù)，你的應(yīng)用程序不能調(diào)用 ********************************************************************************************************* */INT8U OS_TCBInit(INT8U prio, OS_STK *ptos,OS_STK *pbos,INT16U id,INT32U stk_size,void *pext,INT16U opt) {OS_TCB *ptcb; /*指向TCB的指針*/ #if OS_CRITICAL_METHOD == 3u /*將中斷類型設(shè)置為3*/OS_CPU_SR cpu_sr = 0u; #endif #if OS_TASK_REG_TBL_SIZE > 0uINT8U i; #endifOS_ENTER_CRITICAL(); /*關(guān)中斷*/ptcb = OSTCBFreeList; /*ptcb指針指向空閑TCB列表，來(lái)獲得一個(gè)空閑的TCB*/if (ptcb != (OS_TCB *)0) /*如果ptcb不為0，即還有空閑的TCB*/{OSTCBFreeList = ptcb->OSTCBNext; /* Update pointer to free TCB list更新一下空閑TCB列表指針（起始指針后移一個(gè)）*/OS_EXIT_CRITICAL(); /*關(guān)中斷*/ptcb->OSTCBStkPtr = ptos; /*將棧頂指針存儲(chǔ)在ptch中的OSTCBStkPtr */ptcb->OSTCBPrio = prio; /*將優(yōu)先級(jí)存儲(chǔ)在OSTCBPrio中*/ptcb->OSTCBStat = OS_STAT_RDY; /*將TCB的狀態(tài)設(shè)置為就緒態(tài)*/ptcb->OSTCBStatPend = OS_STAT_PEND_OK; /* Clear pend status將掛起狀態(tài)設(shè)置為OS_STAT_PEND_OK*/ptcb->OSTCBDly = 0u; /* Task is not delayed無(wú)任務(wù)延遲，直接執(zhí)行*/#if OS_TASK_CREATE_EXT_EN > 0u /*如果創(chuàng)建的是擴(kuò)展型任務(wù)，存儲(chǔ)有關(guān)的信息*/ptcb->OSTCBExtPtr = pext; ptcb->OSTCBStkSize = stk_size; ptcb->OSTCBStkBottom = pbos; ptcb->OSTCBOpt = opt; ptcb->OSTCBId = id; #else /*不是擴(kuò)展型任務(wù)*/pext = pext; /*pext只針對(duì)擴(kuò)展型任務(wù)，所以這里自己給自己賦值，防止編譯出錯(cuò)*/stk_size = stk_size;pbos = pbos;opt = opt;id = id;#endif#if OS_TASK_DEL_EN > 0uptcb->OSTCBDelReq = OS_ERR_NONE;/*將刪除TCB的請(qǐng)求設(shè)置為OS_ERR_NONE*//*如果可以刪除任務(wù)本身，可以從每個(gè)OS_TCB中節(jié)省出一個(gè)布爾量*/#endif/*提前進(jìn)行相關(guān)計(jì)算，為了節(jié)省CPU的操作事件*/#if OS_LOWEST_PRIO <= 63u ptcb->OSTCBY = (INT8U)(prio >> 3u);ptcb->OSTCBX = (INT8U)(prio & 0x07u);#else ptcb->OSTCBY = (INT8U)((INT8U)(prio >> 4u) & 0xFFu);ptcb->OSTCBX = (INT8U)(prio & 0x0Fu);#endif/* Pre-compute BitX and BitY */ptcb->OSTCBBitY = (OS_PRIO)(1uL << ptcb->OSTCBY);/*提前計(jì)算位掩碼*/ptcb->OSTCBBitX = (OS_PRIO)(1uL << ptcb->OSTCBX);#if (OS_EVENT_EN)ptcb->OSTCBEventPtr = (OS_EVENT *)0; /* 如果不打算在應(yīng)用程序中使用各類事件，OS_TCB中OSTCBEventPt就不會(huì)出現(xiàn)任務(wù)就不會(huì)被掛起Task is not pending on an event*/#if (OS_EVENT_MULTI_EN > 0u)ptcb->OSTCBEventMultiPtr = (OS_EVENT **)0; /* Task is not pending on any events任務(wù)不會(huì)因?yàn)槿魏问录粧炱?/#endif#endif#if (OS_FLAG_EN > 0u) && (OS_MAX_FLAGS > 0u) && (OS_TASK_DEL_EN > 0u)ptcb->OSTCBFlagNode = (OS_FLAG_NODE *)0; /* Task is not pending on an event flag任務(wù)不會(huì)因?yàn)槭录?biāo)志被掛起 */#endif#if (OS_MBOX_EN > 0u) || ((OS_Q_EN > 0u) && (OS_MAX_QS > 0u))ptcb->OSTCBMsg = (void *)0; /* No message received消息數(shù)設(shè)為0*/#endif#if OS_TASK_PROFILE_EN > 0uptcb->OSTCBCtxSwCtr = 0uL; /* Initialize profiling variables初始化分析變量 */ptcb->OSTCBCyclesStart = 0uL;ptcb->OSTCBCyclesTot = 0uL;ptcb->OSTCBStkBase = (OS_STK *)0;ptcb->OSTCBStkUsed = 0uL;#endif#if OS_TASK_NAME_EN > 0uptcb->OSTCBTaskName = (INT8U *)(void *)"?";/*初始化TCB任務(wù)名稱*/#endif#if OS_TASK_REG_TBL_SIZE > 0u /* Initialize the task variables初始化任務(wù)變量*/for (i = 0u; i < OS_TASK_REG_TBL_SIZE; i++) {ptcb->OSTCBRegTbl[i] = 0u;}#endifOSTCBInitHook(ptcb); /*初始化鉤子函數(shù)*/OSTaskCreateHook(ptcb); /* Call user defined hook調(diào)用用戶自定義的鉤子函數(shù)*/OS_ENTER_CRITICAL(); /*關(guān)中斷*/OSTCBPrioTbl[prio] = ptcb; ptcb->OSTCBNext = OSTCBList; /* Link into TCB chain鏈接到任務(wù)控制塊鏈接串*/ptcb->OSTCBPrev = (OS_TCB *)0; if (OSTCBList != (OS_TCB *)0) {OSTCBList->OSTCBPrev = ptcb;}OSTCBList = ptcb;OSRdyGrp |= ptcb->OSTCBBitY; /*通過(guò)掩碼計(jì)算就緒組號(hào)*/OSRdyTbl[ptcb->OSTCBY] |= ptcb->OSTCBBitX;/*通過(guò)掩碼計(jì)算在就緒表中的位置*/OSTaskCtr++; /* 任務(wù)數(shù)目加1*/OS_EXIT_CRITICAL(); /*開(kāi)中斷*/return (OS_ERR_NONE);}OS_EXIT_CRITICAL(); /*開(kāi)中斷*/return (OS_ERR_TASK_NO_MORE_TCB); }
相關(guān)介紹：http://blog.csdn.net/m0_37411189/article/details/72967962

解析在創(chuàng)建任務(wù)時(shí)對(duì)該任務(wù)控制塊的初始化過(guò)程（三步走）：

被創(chuàng)建任務(wù)從空閑任務(wù)控制鏈表（OSTCBFreeList）中獲取一個(gè)任務(wù)控制塊?

2.用任務(wù)的屬性對(duì)任務(wù)控制塊各個(gè)成員進(jìn)行賦值

3.把這個(gè)任務(wù)控制塊鏈入到任務(wù)控制塊鏈表（OSTCBList），并在任務(wù)就緒表中登記該任務(wù)

個(gè)人感覺(jué)源代碼讀起來(lái)有些費(fèi)神，但是這三個(gè)圖表現(xiàn)的很清楚。

到這里，OS_CORE.C文件讀完。

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