μCOS-II中OS_TASK.C源码中文注释版.doc

xilentz的网络文摘博客园 首页 新随笔 联系 订阅 管理 随笔 - 204 文章 - 0评论 - 10trackbacks - 0 OS_TASK.C/* 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 (OSTCBPrioTblnewprio != (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 OSTCBPrioTblnewprio = (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 = OSMapTbly; x = newprio & 0x07; bitx = OSMapTblx; 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 = OSTCBPrioTbloldprio;/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 OSTCBPrioTbloldprio = (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 (OSRdyTblptcb-OSTCBY & ptcb-OSTCBBitX) != 0x00) /* If task is ready make it not */ if (OSRdyTblptcb-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 */ OSRdyTbly |= 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-OSEventTblptcb-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-OSEventTbly |= bitx; #endif OSTCBPrioTblnewprio = 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 OSTCBPrioTblnewprio = (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 didnt 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 tasks 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 tasks 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 tasks 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 (OSTCBPrioTblprio = (OS_TCB *)0) /* Make sure task doesnt already exist at this priority */ /保证优先级没有被其它任务占用 OSTCBPrioTblprio = (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 tasks 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 OSTCBPrioTblprio = (OS_TCB *)0;/* Make this priority available to others */ /把这一优先级给其它任务 OS_EXIT_CRITICAL();/退出临界状态 return (err);/返回错误信息 OS_EXIT_CRITICAL();/如果优先级占用，退出临界状态 return (OS_PRIO_EXIST);/返回优先级存在#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 tasks 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 tasks 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 tasks priority. A unique priority MUST be assigned to each task and the* lower the number, the higher the priority.* id is the tasks ID (0.65535)* pbos is a pointer to the tasks 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)*/* 建立一个任务的扩展版函数描述：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。 它与OSTaskCreate()功能相似，但它允许一个特殊任务的更多信息。参数：task: 指向任务代码的指针 pdata：任务开始执行时，传递给任务参数的指针，用法见上。 ptos：分配给任务堆栈的栈顶指针 prio:分配给任务的优先级 id:为任务创建一个特殊标志符，扩展版本有用。在这里设为和优先级一样即可。 pbos：指向任务堆栈栈底指针，用于堆栈检验 stk_size:用于指定堆栈容量。例：如果堆栈入口宽度为4B，那么stk_size为1000， 说明堆栈有4000B pext：指向用户附加的数据域指针，用来扩展任务的任务控制块OS_TCB opt：设定OSTaskCreateExt的选项，指定是否允许堆栈检验，是否将堆栈清零，是否 进行浮点数操作等。具体见uCOS_II中每一位定义。只要将相应位与opt相或即可返回：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 */*$PAGE*/#if OS_TASK_CREAT