逐字逐句解析ucos ii 源代码-》OS_TASK.c
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//BY 简单的元清 //部分内容引用了其他博主的文章，对这些博主表示感谢，时间关系就不一一指出了。 //如有转载，请说明，谢谢 /*
*********************************************************************************************************
* uC/OS-II
* The Real-Time Kernel
* TASK MANAGEMENT
*
* (c) Copyright 1992-1998, Jean J. Labrosse, Plantation, FL
* All Rights Reserved
*
* V2.00
*
* File : OS_TASK.C
* By : Jean J. Labrosse
*********************************************************************************************************
*/#ifndef OS_MASTER_FILE
#include "software\includes.h"
#endif/*
*********************************************************************************************************
* LOCAL FUNCTION PROTOTYPES
*********************************************************************************************************
*///static void OSDummy(void) reentrant;/*
*********************************************************************************************************
* DUMMY FUNCTION
*
* Description: This function doesn't do anything. It is called by OSTaskDel() to ensure that interrupts
* are disabled immediately after they are enabled.
*
* Arguments : none
*
* Returns : none
*********************************************************************************************************
*/
//确保中断开启到关闭至少有一个指令周期，无具体功能意义
#if OS_TASK_DEL_EN
static void OSDummy (void) reentrant
{}
#endif
/*$PAGE*/
/*
*********************************************************************************************************
* CHANGE PRIORITY OF A TASK
*
* Description: This function allows you to change the priority of a task dynamically. Note that the new
* priority MUST be available.
*
* Arguments : oldp is the old priority
*
* newp is the new priority
*
* Returns : OS_NO_ERR is the call was successful
* OS_PRIO_INVALID if the priority you specify is higher that the maximum allowed
* (i.e. >= OS_LOWEST_PRIO)
* OS_PRIO_EXIST if the new priority already exist.
* OS_PRIO_ERR there is no task with the specified OLD priority (i.e. the OLD task does
* not exist.
*********************************************************************************************************
*/
//改变任务的优先级
#if OS_TASK_CHANGE_PRIO_EN
INT8U OSTaskChangePrio (INT8U oldprio, INT8U newprio) reentrant
{OS_TCB *ptcb;OS_EVENT *pevent;INT8U x;INT8U y;INT8U bitx;INT8U bity;if ((oldprio >= OS_LOWEST_PRIO && oldprio != OS_PRIO_SELF) || newprio >= OS_LOWEST_PRIO) {return (OS_PRIO_INVALID);//判断优先级是否为有效的优先级}OS_ENTER_CRITICAL();//进入临界区if (OSTCBPrioTbl[newprio] != (OS_TCB *)0) { /* New priority must not already exist *///优先级是之前的优先级列表中没有的OS_EXIT_CRITICAL();//退出临界区return (OS_PRIO_EXIST);//返回优先级} else {OSTCBPrioTbl[newprio] = (OS_TCB *)1; /* Reserve the entry to prevent others *///？？？OS_EXIT_CRITICAL();//退出临界区y = newprio >> 3; /* Precompute to reduce INT. latency */bity = OSMapTbl[y];x = newprio & 0x07;bitx = OSMapTbl[x];//改编优先级操作OS_ENTER_CRITICAL();//进入临界区if (oldprio == OS_PRIO_SELF) { /* See if changing self */oldprio = OSTCBCur->OSTCBPrio; /* Yes, get priority */}//如果旧的优先级是自己，将优先级赋值给旧优先级if ((ptcb = OSTCBPrioTbl[oldprio]) != (OS_TCB *)0) { /* Task to change must exist *///要改变的优先级的任务必须存在OSTCBPrioTbl[oldprio] = (OS_TCB *)0; /* Remove TCB from old priority *///先从旧的优先级表中删除if (OSRdyTbl[ptcb->OSTCBY] & ptcb->OSTCBBitX) { /* If task is ready make it not ready *///判断是否有任务就绪if ((OSRdyTbl[ptcb->OSTCBY] &= ~ptcb->OSTCBBitX) == 0) {OSRdyGrp &= ~ptcb->OSTCBBitY;//如果有任务就绪则取消就绪}OSRdyGrp |= bity; /* Make new priority ready to run */OSRdyTbl[y] |= bitx;//新的优先级进入运行} else {if ((pevent = ptcb->OSTCBEventPtr) != (OS_EVENT *)0) { /* Remove from event wait list *///如果任务没有就绪,那么可能在等一个信号量,一个互斥型信号量,一个邮箱,队列等,如果OSTCBEventPtr非空,那么此函数会知道任务正在等以上的某件事.if ((pevent->OSEventTbl[ptcb->OSTCBY] &= ~ptcb->OSTCBBitX) == 0) {pevent->OSEventGrp &= ~ptcb->OSTCBBitY;//从等待列表中移除}pevent->OSEventGrp |= bity; /* Add new priority to wait list */pevent->OSEventTbl[y] |= bitx;//添加新的优先级到等待列表}}OSTCBPrioTbl[newprio] = ptcb; /* Place pointer to TCB @ new priority */ptcb->OSTCBPrio = newprio; /* Set new task priority */ptcb->OSTCBY = y;ptcb->OSTCBX = x;ptcb->OSTCBBitY = bity;ptcb->OSTCBBitX = bitx;//把新的优先级信息填充到PTCB块中OS_EXIT_CRITICAL();//退出临界区OSSched(); /* Run highest priority task ready *///进行一次调度return (OS_NO_ERR);} else {OSTCBPrioTbl[newprio] = (OS_TCB *)0; /* Release the reserved prio. *///如果任务正在等某事件发生,OSTCBEventPtr必须将任务从事件控制块的等待队列(旧的优先级下)中移除OS_EXIT_CRITICAL();//退出临界区return (OS_PRIO_ERR); /* Task to change didn't exist */}}
}
#endif
/*$PAGE*/
/*
*********************************************************************************************************
* CREATE A TASK
*
* Description: This function is used to have uC/OS-II manage the execution of a task. Tasks can either
* be created prior to the start of multitasking or by a running task. A task cannot be
* created by an ISR.
*
* Arguments : task is a pointer to the task's code
*
* pdata is a pointer to an optional data area which can be used to pass parameters to
* the task when the task first executes. Where the task is concerned it thinks
* it was invoked and passed the argument 'pdata' as follows:
*
* void Task (void *pdata)
* {
* for (;;) {
* Task code;
* }
* }
*
* ptos is a pointer to the task's top of stack. If the configuration constant
* OS_STK_GROWTH is set to 1, the stack is assumed to grow downward (i.e. from high
* memory to low memory). 'pstk' will thus point to the highest (valid) memory
* location of the stack. If OS_STK_GROWTH is set to 0, 'pstk' will point to the
* lowest memory location of the stack and the stack will grow with increasing
* memory locations.
*
* prio is the task's priority. A unique priority MUST be assigned to each task and the
* lower the number, the higher the priority.
*
* Returns : OS_NO_ERR if the function was successful.
* OS_PRIO_EXIT if the task priority already exist
* (each task MUST have a unique priority).
* OS_PRIO_INVALID if the priority you specify is higher that the maximum allowed
* (i.e. >= OS_LOWEST_PRIO)
*********************************************************************************************************
*/#if OS_TASK_CREATE_EN
//创建一个任务
INT8U OSTaskCreate (void (*task)(void *pd), void *ppdata, OS_STK *ptos, INT8U prio) reentrant
{void *psp;INT8U err;if (prio > OS_LOWEST_PRIO) { /* Make sure priority is within allowable range */return (OS_PRIO_INVALID);//判断优先级是否有效}OS_ENTER_CRITICAL();//进入临界区if (OSTCBPrioTbl[prio] == (OS_TCB *)0) { /* Make sure task doesn't already exist at this priority */OSTCBPrioTbl[prio] = (OS_TCB *)1; /* Reserve the priority to prevent others from doing ... *//* ... the same thing until task is created. *///判断该优先级是否被占用OS_EXIT_CRITICAL();//退出临界区psp = (void *)OSTaskStkInit(task, ppdata, ptos, 0); /* Initialize the task's stack *///初始化堆栈err = OSTCBInit(prio, psp, (void *)0, 0, 0, (void *)0, 0); //初始化任务控制块if (err == OS_NO_ERR) {//判断初始化是否成功OS_ENTER_CRITICAL();//进入临界区OSTaskCtr++; /* Increment the #tasks counter *///任务计数加加
//**********OSTaskCreateHook(OSTCBPrioTbl[prio]); /* Call user defined hook */OS_EXIT_CRITICAL();//退出临界区if (OSRunning) { /* Find highest priority task if multitasking has started */OSSched();//如果有任务已经开始了，进行调度}} else {OS_ENTER_CRITICAL();//进入临界区OSTCBPrioTbl[prio] = (OS_TCB *)0;/* Make this priority available to others *///这个优先级可以被其他任务调用OS_EXIT_CRITICAL();//退出临界区}return (err);} else {OS_EXIT_CRITICAL();//退出临界区return (OS_PRIO_EXIST);}
}
#endif
/*$PAGE*/
/*
*********************************************************************************************************
* CREATE A TASK (Extended Version)
*
* Description: This function is used to have uC/OS-II manage the execution of a task. Tasks can either
* be created prior to the start of multitasking or by a running task. A task cannot be
* created by an ISR. This function is similar to OSTaskCreate() except that it allows
* additional information about a task to be specified.
*
* Arguments : task is a pointer to the task's code
*
* pdata is a pointer to an optional data area which can be used to pass parameters to
* the task when the task first executes. Where the task is concerned it thinks
* it was invoked and passed the argument 'pdata' as follows:
*
* void Task (void *pdata)
* {
* for (;;) {
* Task code;
* }
* }
*
* ptos is a pointer to the task's top of stack. If the configuration constant
* OS_STK_GROWTH is set to 1, the stack is assumed to grow downward (i.e. from high
* memory to low memory). 'pstk' will thus point to the highest (valid) memory
* location of the stack. If OS_STK_GROWTH is set to 0, 'pstk' will point to the
* lowest memory location of the stack and the stack will grow with increasing
* memory locations. 'pstk' MUST point to a valid 'free' data item.
*
* prio is the task's priority. A unique priority MUST be assigned to each task and the
* lower the number, the higher the priority.
*
* id is the task's ID (0..65535)
*
* pbos is a pointer to the task's bottom of stack. If the configuration constant
* OS_STK_GROWTH is set to 1, the stack is assumed to grow downward (i.e. from high
* memory to low memory). 'pbos' will thus point to the LOWEST (valid) memory
* location of the stack. If OS_STK_GROWTH is set to 0, 'pbos' will point to the
* HIGHEST memory location of the stack and the stack will grow with increasing
* memory locations. 'pbos' MUST point to a valid 'free' data item.
*
* stk_size is the size of the stack in number of elements. If OS_STK is set to INT8U,
* 'stk_size' corresponds to the number of bytes available. If OS_STK is set to
* INT16U, 'stk_size' contains the number of 16-bit entries available. Finally, if
* OS_STK is set to INT32U, 'stk_size' contains the number of 32-bit entries
* available on the stack.
*
* pext is a pointer to a user supplied memory location which is used as a TCB extension.
* For example, this user memory can hold the contents of floating-point registers
* during a context switch, the time each task takes to execute, the number of times
* the task has been switched-in, etc.
*
* opt contains additional information (or options) about the behavior of the task. The
* LOWER 8-bits are reserved by uC/OS-II while the upper 8 bits can be application
* specific. See OS_TASK_OPT_??? in uCOS-II.H.
*
* Returns : OS_NO_ERR if the function was successful.
* OS_PRIO_EXIT if the task priority already exist
* (each task MUST have a unique priority).
* OS_PRIO_INVALID if the priority you specify is higher that the maximum allowed
* (i.e. > OS_LOWEST_PRIO)
*********************************************************************************************************
*/
/*$PAGE*/
#if OS_TASK_CREATE_EXT_EN //创建一个任务（相比于上面那个创建函数，多了一些配置内容）
INT8U OSTaskCreateExt (void (*task)(void *pd), void *ppdata, OS_STK *ptos, INT8U prio,INT16U id,OS_STK *pbos,INT32U stk_size,void *pext,INT16U opt) reentrant
{void *psp;INT8U err;INT16U i;OS_STK *pfill;if (prio > OS_LOWEST_PRIO) { /* Make sure priority is within allowable range */return (OS_PRIO_INVALID);}//先判断优先级是否有效OS_ENTER_CRITICAL();//进入临界区if (OSTCBPrioTbl[prio] == (OS_TCB *)0) { /* Make sure task doesn't already exist at this priority */OSTCBPrioTbl[prio] = (OS_TCB *)1; /* Reserve the priority to prevent others from doing ... *///判断该优先级是否被占用 /* ... the same thing until task is created. */OS_EXIT_CRITICAL();//退出临界区if (opt & OS_TASK_OPT_STK_CHK) { /* See if stack checking has been enabled *///判断可选项是否使能if (opt & OS_TASK_OPT_STK_CLR) { /* See if stack needs to be cleared *///判断opt的内容是否为清除pfill = pbos; /* Yes, fill the stack with zeros *///把栈清零for (i = 0; i < stk_size; i++) {#if OS_STK_GROWTH == 1*pfill++ = (OS_STK)0;#else*pfill-- = (OS_STK)0;#endif}}}//和上面的一样，不再分析psp = (void *)OSTaskStkInit(task, ppdata, ptos, opt); /* Initialize the task's stack */err = OSTCBInit(prio, psp, pbos, id, stk_size, pext, opt); if (err == OS_NO_ERR) {OS_ENTER_CRITICAL();OSTaskCtr++; /* Increment the #tasks counter */OSTaskCreateHook(OSTCBPrioTbl[prio]); /* Call user defined hook */OS_EXIT_CRITICAL();if (OSRunning) { /* Find highest priority task if multitasking has started */OSSched();}} else {OS_ENTER_CRITICAL();OSTCBPrioTbl[prio] = (OS_TCB *)0;/* Make this priority available to others */OS_EXIT_CRITICAL();}return (err);} else {OS_EXIT_CRITICAL();return (OS_PRIO_EXIST);}
}
#endif
/*$PAGE*/
/*
*********************************************************************************************************
* DELETE A TASK
*
* Description: This function allows you to delete a task. The calling task can delete itself by
* its own priority number. The deleted task is returned to the dormant state and can be
* re-activated by creating the deleted task again.
*
* Arguments : prio is the priority of the task to delete. Note that you can explicitely delete
* the current task without knowing its priority level by setting 'prio' to
* OS_PRIO_SELF.
*
* Returns : OS_NO_ERR if the call is successful
* OS_TASK_DEL_IDLE if you attempted to delete uC/OS-II's idle task
* OS_PRIO_INVALID if the priority you specify is higher that the maximum allowed
* (i.e. >= OS_LOWEST_PRIO) or, you have not specified OS_PRIO_SELF.
* OS_TASK_DEL_ERR if the task you want to delete does not exist
* OS_TASK_DEL_ISR if you tried to delete a task from an ISR
*
* Notes : 1) To reduce interrupt latency, OSTaskDel() 'disables' the task:
* a) by making it not ready
* b) by removing it from any wait lists
* c) by preventing OSTimeTick() from making the task ready to run.
* The task can then be 'unlinked' from the miscellaneous structures in uC/OS-II.
* 2) The function OSDummy() is called after OS_EXIT_CRITICAL() because, on most processors,
* the next instruction following the enable interrupt instruction is ignored. You can
* replace OSDummy() with a macro that basically executes a NO OP (i.e. OS_NOP()). The
* NO OP macro would avoid the execution time of the function call and return.
* 3) An ISR cannot delete a task.
* 4) The lock nesting counter is incremented because, for a brief instant, if the current
* task is being deleted, the current task would not be able to be rescheduled because it
* is removed from the ready list. Incrementing the nesting counter prevents another task
* from being schedule. This means that the ISR would return to the current task which is
* being deleted. The rest of the deletion would thus be able to be completed.
*********************************************************************************************************
*/
/*$PAGE*/
#if OS_TASK_DEL_EN
//
INT8U OSTaskDel (INT8U prio) reentrant
{OS_TCB *ptcb;OS_EVENT *pevent;if (prio == OS_IDLE_PRIO) { /* Not allowed to delete idle task */return (OS_TASK_DEL_IDLE);}//空闲任务不能被删除if (prio >= OS_LOWEST_PRIO && prio != OS_PRIO_SELF) { /* Task priority valid ? */return (OS_PRIO_INVALID);}//确认优先级是否有效OS_ENTER_CRITICAL();//进入临界区if (OSIntNesting > 0) { /* See if trying to delete from ISR */OS_EXIT_CRITICAL();return (OS_TASK_DEL_ISR);}//如果有中断产生，退出临界区if (prio == OS_PRIO_SELF) { /* See if requesting to delete self */prio = OSTCBCur->OSTCBPrio; /* Set priority to delete to current */}//判断是否为删除自身if ((ptcb = OSTCBPrioTbl[prio]) != (OS_TCB *)0) { /* Task to delete must exist *///判断任务是否存在if ((OSRdyTbl[ptcb->OSTCBY] &= ~ptcb->OSTCBBitX) == 0) {/* Make task not ready */OSRdyGrp &= ~ptcb->OSTCBBitY;}//确认任务不再就绪态if ((pevent = ptcb->OSTCBEventPtr) != (OS_EVENT *)0) { /* If task is waiting on event *///判断是否有事件发生if ((pevent->OSEventTbl[ptcb->OSTCBY] &= ~ptcb->OSTCBBitX) == 0) { /* ... remove task from */pevent->OSEventGrp &= ~ptcb->OSTCBBitY; /* ... event ctrl block */}//把等待状态的任务从组中删除}ptcb->OSTCBDly = 0; /* Prevent OSTimeTick() from updating *///把等待时间设置为零ptcb->OSTCBStat = OS_STAT_RDY; /* Prevent task from being resumed *///PTCB的状态进行设置OSLockNesting++;//调度锁加一OS_EXIT_CRITICAL(); /* Enabling INT. ignores next instruc. *///退出临界区OSDummy(); /* ... Dummy ensures that INTs will be *///该函数并不会进行任何实质性的工作。这样做只是因为想确保处理器在中断允许的情况下至少执行一个指令OS_ENTER_CRITICAL(); /* ... disabled HERE! *///进入临界区OSLockNesting--;//调度锁减一OSTaskDelHook(ptcb); /* Call user defined hook *///删除钩子函数OSTaskCtr--; /* One less task being managed *///任务的数量减一OSTCBPrioTbl[prio] = (OS_TCB *)0; /* Clear old priority entry *///删除原来优先级的指针指向if (ptcb->OSTCBPrev == (OS_TCB *)0) { /* Remove from TCB chain */ptcb->OSTCBNext->OSTCBPrev = (OS_TCB *)0;OSTCBList = ptcb->OSTCBNext;//删除TCB链} else {ptcb->OSTCBPrev->OSTCBNext = ptcb->OSTCBNext;ptcb->OSTCBNext->OSTCBPrev = ptcb->OSTCBPrev;//删除TCB链}ptcb->OSTCBNext = OSTCBFreeList; /* Return TCB to free TCB list *///把OSTCBNext指向空的列表OSTCBFreeList = ptcb;//OSTCBFreeList指向ptcbOS_EXIT_CRITICAL();//退出临界区OSSched(); /* Find new highest priority task *///进行一次调度return (OS_NO_ERR);} else {OS_EXIT_CRITICAL();//退出临界区return (OS_TASK_DEL_ERR);}
}
#endif
/*$PAGE*/
/*
*********************************************************************************************************
* REQUEST THAT A TASK DELETE ITSELF
*
* Description: This function is used to:
* a) notify a task to delete itself.
* b) to see if a task requested that the current task delete itself.
* This function is a little tricky to understand. Basically, you have a task that needs
* to be deleted however, this task has resources that it has allocated (memory buffers,
* semaphores, mailboxes, queues etc.). The task cannot be deleted otherwise these
* resources would not be freed. The requesting task calls OSTaskDelReq() to indicate that
* the task needs to be deleted. Deleting of the task is however, deferred to the task to
* be deleted. For example, suppose that task #10 needs to be deleted. The requesting task
* example, task #5, would call OSTaskDelReq(10). When task #10 gets to execute, it calls
* this function by specifying OS_PRIO_SELF and monitors the returned value. If the return
* value is OS_TASK_DEL_REQ, another task requested a task delete. Task #10 would look like
* this:
*
* void Task(void *data)
* {
* .
* .
* while (1) {
* OSTimeDly(1);
* if (OSTaskDelReq(OS_PRIO_SELF) == OS_TASK_DEL_REQ) {
* Release any owned resources;
* De-allocate any dynamic memory;
* OSTaskDel(OS_PRIO_SELF);
* }
* }
* }
*
* Arguments : prio is the priority of the task to request the delete from
*
* Returns : OS_NO_ERR if the task exist and the request has been registered
* OS_TASK_NOT_EXIST if the task has been deleted. This allows the caller to know whether
* the request has been executed.
* OS_TASK_DEL_IDLE if you requested to delete uC/OS-II's idle task
* OS_PRIO_INVALID if the priority you specify is higher that the maximum allowed
* (i.e. >= OS_LOWEST_PRIO) or, you have not specified OS_PRIO_SELF.
* OS_TASK_DEL_REQ if a task (possibly another task) requested that the running task be
* deleted.
*********************************************************************************************************
*/
/*$PAGE*/
#if OS_TASK_DEL_EN
//请求删除任务函数
INT8U OSTaskDelReq (INT8U prio) reentrant
{BOOLEAN stat;INT8U err;OS_TCB *ptcb;if (prio == OS_IDLE_PRIO) { /* Not allowed to delete idle task */return (OS_TASK_DEL_IDLE);}//判断是否为空闲任务if (prio >= OS_LOWEST_PRIO && prio != OS_PRIO_SELF) { /* Task priority valid ? */return (OS_PRIO_INVALID);}//判断是否为有效的任务if (prio == OS_PRIO_SELF) { /* See if a task is requesting to ... *///判断是否为删除自身OS_ENTER_CRITICAL(); /* ... this task to delete itself *///进入临界区stat = OSTCBCur->OSTCBDelReq; /* Return request status to caller *///把删除请求状态配置给statOS_EXIT_CRITICAL();//退出临界区return (stat);//返回stat} else {OS_ENTER_CRITICAL();//进入临界区if ((ptcb = OSTCBPrioTbl[prio]) != (OS_TCB *)0) { /* Task to delete must exist *///判断任务是否存在ptcb->OSTCBDelReq = OS_TASK_DEL_REQ; /* Set flag indicating task to be DEL. *///删除请求赋值给ptcberr = OS_NO_ERR;//返回错误码} else {err = OS_TASK_NOT_EXIST; /* Task must be deleted *///任务不存在返回错误码}OS_EXIT_CRITICAL();//退出临界区return (err);}
}
#endif
/*$PAGE*/
/*
*********************************************************************************************************
* RESUME A SUSPENDED TASK
*
* Description: This function is called to resume a previously suspended task. This is the only call that
* will remove an explicit task suspension.
*
* Arguments : prio is the priority of the task to resume.
*
* Returns : OS_NO_ERR if the requested task is resumed
* OS_PRIO_INVALID if the priority you specify is higher that the maximum allowed
* (i.e. >= OS_LOWEST_PRIO)
* OS_TASK_RESUME_PRIO if the task to resume does not exist
* OS_TASK_NOT_SUSPENDED if the task to resume has not been suspended
*********************************************************************************************************
*/#if OS_TASK_SUSPEND_EN
//恢复任务函数
INT8U OSTaskResume (INT8U prio) reentrant
{OS_TCB *ptcb;if (prio >= OS_LOWEST_PRIO) { /* Make sure task priority is valid */return (OS_PRIO_INVALID);}//判断优先级是否有效OS_ENTER_CRITICAL();//进入临界区if ((ptcb = OSTCBPrioTbl[prio]) == (OS_TCB *)0) { /* Task to suspend must exist *///被挂起的任务必须存在OS_EXIT_CRITICAL();//退出临界区return (OS_TASK_RESUME_PRIO);} else {if (ptcb->OSTCBStat & OS_STAT_SUSPEND) { /* Task must be suspended *///确认任务的状态是挂起态if (((ptcb->OSTCBStat &= ~OS_STAT_SUSPEND) == OS_STAT_RDY) && /* Remove suspension *///确认是挂起态同时等待时间为0(ptcb->OSTCBDly == 0)) { /* Must not be delayed */OSRdyGrp |= ptcb->OSTCBBitY; /* Make task ready to run */OSRdyTbl[ptcb->OSTCBY] |= ptcb->OSTCBBitX;//把任务加入就绪列表OS_EXIT_CRITICAL();//退出临界区OSSched();//进行调度} else {OS_EXIT_CRITICAL();//退出临界区}return (OS_NO_ERR);} else {OS_EXIT_CRITICAL();return (OS_TASK_NOT_SUSPENDED);}}
}
#endif
/*$PAGE*/
/*
*********************************************************************************************************
* STACK CHECKING
*
* Description: This function is called to check the amount of free memory left on the specified task's
* stack.
*
* Arguments : prio is the task priority
*
* pdata is a pointer to a data structure of type OS_STK_DATA.
*
* Returns : OS_NO_ERR upon success
* OS_PRIO_INVALID if the priority you specify is higher that the maximum allowed
* (i.e. > OS_LOWEST_PRIO) or, you have not specified OS_PRIO_SELF.
* OS_TASK_NOT_EXIST if the desired task has not been created
* OS_TASK_OPT_ERR if you did NOT specified OS_TASK_OPT_STK_CHK when the task was created
*********************************************************************************************************
*/
#if OS_TASK_CREATE_EXT_EN
//任务堆栈状态检查函数
INT8U OSTaskStkChk (INT8U prio, OS_STK_DATA *ppdata) reentrant
{OS_TCB *ptcb;OS_STK *pchk;INT32U free;INT32U size;ppdata->OSFree = 0; /* Assume failure, set to 0 size */ppdata->OSUsed = 0;if (prio > OS_LOWEST_PRIO && prio != OS_PRIO_SELF) { /* Make sure task priority is valid */return (OS_PRIO_INVALID);}//判断优先级是否有效OS_ENTER_CRITICAL();//进入临界区if (prio == OS_PRIO_SELF) { /* See if check for SELF */prio = OSTCBCur->OSTCBPrio;}//判断是否为自身，需要将prio的值更改为当前正在执行任务的优先级*/ ptcb = OSTCBPrioTbl[prio];//根据任务的优先级和TCB优先级表，找到所要进程堆栈检测任务的TCBif (ptcb == (OS_TCB *)0) { /* Make sure task exist *///确认任务是否存在OS_EXIT_CRITICAL();//退出临界区return (OS_TASK_NOT_EXIST);}if ((ptcb->OSTCBOpt & OS_TASK_OPT_STK_CHK) == 0) { /* Make sure stack checking option is set *///判断是否允许进行堆栈检查OS_EXIT_CRITICAL();//退出临界区return (OS_TASK_OPT_ERR);}free = 0;// 将需要存放空闲堆栈大小的单元清零 size = ptcb->OSTCBStkSize;//读取任务的堆栈的大小 pchk = ptcb->OSTCBStkBottom;//读取栈底的值OS_EXIT_CRITICAL();//退出临界区
#if OS_STK_GROWTH == 1while (*pchk++ == 0) { /* Compute the number of zero entries on the stk */free++;}
#elsewhile (*pchk-- == 0) {free++;}
#endif
// /*根据系统硬件的情况，进行空闲堆栈的计算*/ ppdata->OSFree = free * sizeof(OS_STK); /* Compute number of free bytes on the stack */ppdata->OSUsed = (size - free) * sizeof(OS_STK); /* Compute number of bytes used on the stack */return (OS_NO_ERR);// 堆栈使用情况计算完毕，填写到所要存储的单元中,并返回堆栈查询没有出错
}
#endif
/*$PAGE*/
/*
*********************************************************************************************************
* SUSPEND A TASK
*
* Description: This function is called to suspend a task. The task can be the calling task if the
* priority passed to OSTaskSuspend() is the priority of the calling task or OS_PRIO_SELF.
*
* Arguments : prio is the priority of the task to suspend. If you specify OS_PRIO_SELF, the
* calling task will suspend itself and rescheduling will occur.
*
* Returns : OS_NO_ERR if the requested task is suspended
* OS_TASK_SUSPEND_IDLE if you attempted to suspend the idle task which is not allowed.
* OS_PRIO_INVALID if the priority you specify is higher that the maximum allowed
* (i.e. >= OS_LOWEST_PRIO) or, you have not specified OS_PRIO_SELF.
* OS_TASK_SUSPEND_PRIO if the task to suspend does not exist
*
* Note : You should use this function with great care. If you suspend a task that is waiting for
* an event (i.e. a message, a semaphore, a queue ...) you will prevent this task from
* running when the event arrives.
*********************************************************************************************************
*/#if OS_TASK_SUSPEND_EN
//将任务挂起函数
INT8U OSTaskSuspend (INT8U prio) reentrant
{BOOLEAN self;OS_TCB *ptcb;if (prio == OS_IDLE_PRIO) { /* Not allowed to suspend idle task */return (OS_TASK_SUSPEND_IDLE);}//不能挂起空闲任务if (prio >= OS_LOWEST_PRIO && prio != OS_PRIO_SELF) { /* Task priority valid ? */return (OS_PRIO_INVALID);}//判断任务是否有效OS_ENTER_CRITICAL();//进入临界区if (prio == OS_PRIO_SELF) { /* See if suspend SELF */prio = OSTCBCur->OSTCBPrio;self = TRUE;//判断挂起的任务是否是自身，如果是自身，需要更新自身的优先级} else if (prio == OSTCBCur->OSTCBPrio) { /* See if suspending self */self = TRUE;//将自身的标志位置位} else {self = FALSE; /* No suspending another task *///不是自身就不置位}if ((ptcb = OSTCBPrioTbl[prio]) == (OS_TCB *)0) { /* Task to suspend must exist *///判断任务是否存在 OS_EXIT_CRITICAL();//退出临界区return (OS_TASK_SUSPEND_PRIO);//返回被挂起的优先级} else {if ((OSRdyTbl[ptcb->OSTCBY] &= ~ptcb->OSTCBBitX) == 0) { /* Make task not ready *///判断任务是否就绪OSRdyGrp &= ~ptcb->OSTCBBitY;//从就绪列表中删除}ptcb->OSTCBStat |= OS_STAT_SUSPEND; /* Status of task is 'SUSPENDED' *///Ptcb快的状态改为挂起态OS_EXIT_CRITICAL();//退出临界区if (self == TRUE) { /* Context switch only if SELF */OSSched();//如果挂起自身，进行一次调度}return (OS_NO_ERR);}
}
#endif
/*$PAGE*/
/*
*********************************************************************************************************
* QUERY A TASK
*
* Description: This function is called to obtain a copy of the desired task's TCB.
*
* Arguments : prio is the priority of the task to obtain information from.
*
* Returns : OS_NO_ERR if the requested task is suspended
* OS_PRIO_INVALID if the priority you specify is higher that the maximum allowed
* (i.e. > OS_LOWEST_PRIO) or, you have not specified OS_PRIO_SELF.
* OS_PRIO_ERR if the desired task has not been created
*********************************************************************************************************
*/#if OS_TASK_QUERY_EN > 0
//查询任务的状态
INT8U OSTaskQuery (INT8U prio, OS_TCB *ppdata) reentrant
{OS_TCB *ptcb;if (prio > OS_LOWEST_PRIO && prio != OS_PRIO_SELF) { /* Task priority valid ? */return (OS_PRIO_INVALID);}//判断任务的优先级是否有效OS_ENTER_CRITICAL();//进入临界区if (prio == OS_PRIO_SELF) { /* See if suspend SELF */prio = OSTCBCur->OSTCBPrio;}//判断挂起的任务是否是自身，如果是自身，需要更新自身的优先级if ((ptcb = OSTCBPrioTbl[prio]) == (OS_TCB *)0) { /* Task to query must exist *///判断任务是否存在OS_EXIT_CRITICAL();//退出临界区return (OS_PRIO_ERR);}*ppdata = *ptcb; /* Copy TCB into user storage area *///把pctb指针指向ppdataOS_EXIT_CRITICAL();//退出临界区return (OS_NO_ERR);//返回错误码
}
#endif
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