os_task.c

avr ucos 代码 测试环境：source insight WINAVR 4个进程

/*
*********************************************************************************************************
*                                                uC/OS-II
*                                          The Real-Time Kernel
*                                            TASK MANAGEMENT
*
*                          (c) Copyright 1992-2002, Jean J. Labrosse, Weston, FL
*                                           All Rights Reserved
*
* File : OS_TASK.C
* By   : Jean J. Labrosse
*********************************************************************************************************
*/

#ifndef  OS_MASTER_FILE
#include "includes.h"
#endif

/*
*********************************************************************************************************
*                                        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.
*********************************************************************************************************
*/
/*
*********************************************************************************************************
                                                   改变任务优先级
描述：此函数允许你动态改变一个任务的优先级。但新的优先级必须可行
参数：oldp ：旧的优先级
                 newp：新的优先级
返回：OS_NO_ERR：改变成功
                OS_PRIO_INVALID：指定的优先级不合法：超过最大值
                OS_PRIO_EXIST：新优先级已经存在
                OS_PRIO_ERR：旧优先级任务不存在

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


#if OS_TASK_CHANGE_PRIO_EN > 0     //如果OS_TASK_CHANGE_PRIO_EN设置为1,能使包含下面代码
INT8U  OSTaskChangePrio (INT8U oldprio, INT8U newprio)
{
#if OS_CRITICAL_METHOD == 3                      /* Allocate storage for CPU status register           */
                                                 //为CPU状态寄存器分配存储器
    OS_CPU_SR    cpu_sr;     //OS_CPU_SR即为unsigned int 
#endif

#if OS_EVENT_EN > 0
//OS_EVENT_EN 定义为：(((OS_Q_EN > 0) && (OS_MAX_QS > 0)) || (OS_MBOX_EN > 0) || (OS_SEM_EN > 0) || (OS_MUTEX_EN > 0))
//OS_EVENT_EN 定义为：能使队列代码产生&&申请队列控制块最大数不为零||能使邮箱代码产生||
//能使信号量代码产生||能使互斥量代码产生 
    OS_EVENT    *pevent;
#endif

    OS_TCB      *ptcb;
    INT8U        x;
    INT8U        y;
    INT8U        bitx;
    INT8U        bity;



#if OS_ARG_CHK_EN > 0//允许参数检测
    if ((oldprio >= OS_LOWEST_PRIO && oldprio != OS_PRIO_SELF)  ||
         newprio >= OS_LOWEST_PRIO) {//旧新优先级都不合法
        return (OS_PRIO_INVALID);
    }
#endif
    OS_ENTER_CRITICAL();//如果合法
    if (OSTCBPrioTbl[newprio] != (OS_TCB *)0) {                 /* New priority must not already exist */
        OS_EXIT_CRITICAL();
        return (OS_PRIO_EXIST);//新优先级必须不存在,存在就重复了
    } else {
        OSTCBPrioTbl[newprio] = (OS_TCB *)1;                    /* Reserve the entry to prevent others */
		//保留入口,防止其它任务占用此优先级
        OS_EXIT_CRITICAL();
        y    = newprio >> 3;                                    /* Precompute to reduce INT. latency   */
		//此函数会预先计算新优先级任务的任务控制块中的某些值,使用这些值
		//可以将任务放入就绪步或者从该表中移除任务.
        bity = OSMapTbl[y];
        x    = newprio & 0x07;
        bitx = OSMapTbl[x];
        OS_ENTER_CRITICAL();
        if (oldprio == OS_PRIO_SELF) {                          /* See if changing self                */
			//如果改变自己
            oldprio = OSTCBCur->OSTCBPrio;                      /* Yes, get priority                   */
        }//是的,得到优先级
        ptcb = OSTCBPrioTbl[oldprio];//得到该优先级TCB指针
        if (ptcb != (OS_TCB *)0) {                              /* Task to change must exist           */
			//优先级存在,如果要改变的是当前任务,由一定会成功
            OSTCBPrioTbl[oldprio] = (OS_TCB *)0;                /* Remove TCB from old priority        */
		//通过放入空闲指针,将指向当前任务的TCB指针从优先级列表中删除,
		//使当前旧的优先级空闲,可以被其它任务占用.
            if ((OSRdyTbl[ptcb->OSTCBY] & ptcb->OSTCBBitX) != 0x00) {  /* If task is ready make it not */
                if ((OSRdyTbl[ptcb->OSTCBY] &= ~ptcb->OSTCBBitX) == 0x00) {	//如果要改变优先级的任务就绪
                    OSRdyGrp &= ~ptcb->OSTCBBitY;//不能让它就绪,
                }
                OSRdyGrp    |= bity;                            /* Make new priority ready to run      */
                OSRdyTbl[y] |= bitx;//从就绪表中移除,然后在新优先级下,将任务插入就绪表,
                //注意:OSTaskChangePrio是利用预先计算的值(见前面)将任务插入就绪表中的.
#if OS_EVENT_EN > 0
//#define  OS_EVENT_EN       (((OS_Q_EN > 0) && (OS_MAX_QS > 0)) || (OS_MBOX_EN > 0) || (OS_SEM_EN > 0) || (OS_MUTEX_EN > 0))
			//能使队列代码产生&&申请队列控制块最大数不为零||能使邮箱代码产生||
			//能使信号量代码产生||能使互斥量代码产生

            } else {
                pevent = ptcb->OSTCBEventPtr;
                if (pevent != (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;
                    }
                    pevent->OSEventGrp    |= bity;              /* Add new priority to wait list       */
	//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,并在新的优先级下将事件插入到等待队列中.任务也可能正
	//在等待延时时间到,或被挂起,上面几行可以省略
                    pevent->OSEventTbl[y] |= bitx;
                }
#endif
            }
            OSTCBPrioTbl[newprio] = ptcb;                       /* Place pointer to TCB @ new priority */
			//将指向任务的OS-TCB的指针存到OSTCBPrioTbl[]中.
            ptcb->OSTCBPrio       = newprio;                    /* Set new task priority               */
			//新的优先级保存在OSTCB中,预先值也保存在OSTCB中.
            ptcb->OSTCBY          = y;
            ptcb->OSTCBX          = x;
            ptcb->OSTCBBitY       = bity;
            ptcb->OSTCBBitX       = bitx;
            OS_EXIT_CRITICAL();
            OS_Sched();                                         /* Run highest priority task ready     */
            //任务调度,运行最高优先级任务,在新的优先级高于旧的优先有或者新的优先级高于调
            //用此函数任务优先级的时候,此函数会被调用
            return (OS_NO_ERR);
        } else {
            OSTCBPrioTbl[newprio] = (OS_TCB *)0;                /* Release the reserved prio.          */
			//如果任务不存在,释放新优先级的TCB
            OS_EXIT_CRITICAL();
            return (OS_PRIO_ERR);                               /* Task to change didn't exist         */
        }//返回
    }
}
#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)
*********************************************************************************************************
*/
/*
*********************************************************************************************
                                                           建立一个任务
 描述：这个函数用于ucosII处理完成一个任务，它要么在多任务处理之前建立，
                  要么运行任务建立，它不够由中断服务程序建立。
参数：task: 指向任务代码的指针。
                 pdata:是一个指向非强制性数据区域的指针，当任务优先运行时传递
                 参数给任务。任务有关部分假想它被唤醒，然后按照以下方式传递pdata：
*                           void Task (void *pdata)
*                           {
*                               for (;;) {
*                                   Task code;
*                               }
*                           }
                ptos：指向任务堆栈顶部的指针，如果配置常数 OS_STK_GROWTH 设置为1的话，堆栈则会由高到低增长（由高地址向低地址存储）。所以
“pstk”会指向堆栈存储器位置的最高地址；如果 OS_STK_GROWTH 设置为0的话，“pstk”将指向堆栈
最低存储器位置，堆栈将按存储器位置递增。
             prio：是任务的优先级，一个独特的优先级必须指定给每个任务，最小的数对应最高优先级。

                 返回：OS_NO_ERR   ：如果函数成功。
                                  OS_PRIO_EXIT ：如果优先级已经存在。
                                  OS_PRIO_INVALID：如果定义优先级的数大于最大值
                 
*********************************************************************************************
*/

#if OS_TASK_CREATE_EN > 0   //能使包含任务创建代码
INT8U  OSTaskCreate (void (*task)(void *pd), void *pdata, OS_STK *ptos, INT8U prio)//上面有说明
{
#if OS_CRITICAL_METHOD == 3                  /* Allocate storage for CPU status register               */
                                //  为CPU状态寄存器分配存储空间
    OS_CPU_SR  cpu_sr;         //CPU状态字是十六位 OS_CPU_SR为unsigned int 
#endif
    OS_STK    *psp;
    INT8U      err;


#if OS_ARG_CHK_EN > 0
//如果OS_ARG_CHK_EN 设为1，OSTaskCreate会检查分配给任务的优先级是否有效。
//系统在执行初始化的时候，已经把最低优先级分配给了空闲任务。
//所以不能用最低优先级来创建任务。
    if (prio > OS_LOWEST_PRIO) {             /* Make sure priority is within allowable range           */
		                                 //保证优先级在允许范围内
        return (OS_PRIO_INVALID);
    }
#endif
    OS_ENTER_CRITICAL();                  //进入临界状态
    if (OSTCBPrioTbl[prio] == (OS_TCB *)0) { /* Make sure task doesn't already exist at this priority  */
		                                   //保证优先级没有被其它任务占用
        OSTCBPrioTbl[prio] = (OS_TCB *)1;    /* Reserve the priority to prevent others from doing ...  */
                                             /* ... the same thing until task is created.              */
								//放置一个非空指针，表示已经占用
        OS_EXIT_CRITICAL();        //退出临界状态
        psp = (OS_STK *)OSTaskStkInit(task, pdata, ptos, 0);    /* Initialize the task's stack         */
		                     //初始化任务堆栈,即建立任务堆栈
        err = OS_TCBInit(prio, psp, (OS_STK *)0, 0, 0, (void *)0, 0);
							 //初始化任务控制块，从空闲的OS_TCB缓冲池
							 //中获得并初始化一个任务控制块
        if (err == OS_NO_ERR) {         //如果初始化没有错
            OS_ENTER_CRITICAL();//进入临界状态
            OSTaskCtr++;                                        /* Increment the #tasks counter        */
			//任务数量加一
            OS_EXIT_CRITICAL();//退出临界状态
            if (OSRunning == TRUE) {         /* Find highest priority task if multitasking has started */
				//如果多任务开始，寻找最高优先级任务
                OS_Sched();
            }
        } else {              //如果初始化任务控制块有错
            OS_ENTER_CRITICAL();//进入临界状态
            OSTCBPrioTbl[prio] = (OS_TCB *)0;/* Make this priority available to others                 */
			//把这一优先级给其它任务