os_task.c

完整的ucos实例

/* 
********************************************************************************************************* 
*                                                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. 
********************************************************************************************************* 
*/ 
 
#if OS_TASK_CHANGE_PRIO_EN > 0 
INT8U  OSTaskChangePrio (INT8U oldprio, INT8U newprio) 
{ 
#if OS_CRITICAL_METHOD == 3                      /* Allocate storage for CPU status register           */ 
    OS_CPU_SR    cpu_sr; 
#endif 
 
#if OS_EVENT_EN > 0 
    OS_EVENT    *pevent; 
#endif 
 
    OS_TCB      *ptcb; 
    INT8U        x; 
    INT8U        y; 
    INT8U        bitx; 
    INT8U        bity; 
 
 
 
#if OS_ARG_CHK_EN > 0 
    if ((oldprio >= OS_LOWEST_PRIO && oldprio != OS_PRIO_SELF)  || 
         newprio >= OS_LOWEST_PRIO) { 
        return (OS_PRIO_INVALID); 
    } 
#endif 
    OS_ENTER_CRITICAL(); 
    if (OSTCBPrioTbl[newprio] != (OS_TCB *)0) {                 /* New priority must not already exist */ 
        OS_EXIT_CRITICAL(); 
        return (OS_PRIO_EXIST); 
    } else { 
        OSTCBPrioTbl[newprio] = (OS_TCB *)1;                    /* Reserve the entry to prevent others */ 
        OS_EXIT_CRITICAL(); 
        y    = newprio >> 3;                                    /* Precompute to reduce INT. latency   */ 
        bity = OSMapTbl[y]; 
        x    = newprio & 0x07; 
        bitx = OSMapTbl[x]; 
        OS_ENTER_CRITICAL(); 
        if (oldprio == OS_PRIO_SELF) {                          /* See if changing self                */ 
            oldprio = OSTCBCur->OSTCBPrio;                      /* Yes, get priority                   */ 
        } 
        ptcb = OSTCBPrioTbl[oldprio]; 
        if (ptcb != (OS_TCB *)0) {                              /* Task to change must exist           */ 
            OSTCBPrioTbl[oldprio] = (OS_TCB *)0;                /* Remove TCB from old priority        */ 
            if ((OSRdyTbl[ptcb->OSTCBY] & ptcb->OSTCBBitX) != 0x00) {  /* If task is ready make it not */ 
                if ((OSRdyTbl[ptcb->OSTCBY] &= ~ptcb->OSTCBBitX) == 0x00) { 
                    OSRdyGrp &= ~ptcb->OSTCBBitY; 
                } 
                OSRdyGrp    |= bity;                            /* Make new priority ready to run      */ 
                OSRdyTbl[y] |= bitx; 
#if OS_EVENT_EN > 0 
            } else { 
                pevent = ptcb->OSTCBEventPtr; 
                if (pevent != (OS_EVENT *)0) {                  /* Remove from event wait list  */ 
                    if ((pevent->OSEventTbl[ptcb->OSTCBY] &= ~ptcb->OSTCBBitX) == 0) { 
                        pevent->OSEventGrp &= ~ptcb->OSTCBBitY; 
                    } 
                    pevent->OSEventGrp    |= bity;              /* Add new priority to wait list       */ 
                    pevent->OSEventTbl[y] |= bitx; 
                } 
#endif 
            } 
            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; 
            OS_EXIT_CRITICAL(); 
            OS_Sched();                                         /* Run highest priority task ready     */ 
            return (OS_NO_ERR); 
        } else { 
            OSTCBPrioTbl[newprio] = (OS_TCB *)0;                /* Release the reserved prio.          */ 
            OS_EXIT_CRITICAL(); 
            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 > 0 
INT8U  OSTaskCreate (void (*task)(void *pd), void *pdata, OS_STK *ptos, INT8U prio) 
{ 
#if OS_CRITICAL_METHOD == 3                  /* Allocate storage for CPU status register               */ 
    OS_CPU_SR  cpu_sr; 
#endif 
    OS_STK    *psp; 
    INT8U      err; 
 
 
#if OS_ARG_CHK_EN > 0 
    if (prio > OS_LOWEST_PRIO) {             /* Make sure priority is within allowable range           */ 
        return (OS_PRIO_INVALID); 
    } 
#endif 
    OS_ENTER_CRITICAL(); 
    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.              */ 
        OS_EXIT_CRITICAL(); 
        psp = (OS_STK *)OSTaskStkInit(task, pdata, ptos, 0);    /* Initialize the task's stack         */ 
        err = OS_TCBInit(prio, psp, (OS_STK *)0, 0, 0, (void *)0, 0); 
        if (err == OS_NO_ERR) { 
            OS_ENTER_CRITICAL(); 
            OSTaskCtr++;                                        /* Increment the #tasks counter        */ 
            OS_EXIT_CRITICAL(); 
            if (OSRunning == TRUE) {         /* Find highest priority task if multitasking has started */ 
                OS_Sched(); 
            } 
        } else { 
            OS_ENTER_CRITICAL(); 
            OSTCBPrioTbl[prio] = (OS_TCB *)0;/* Make this priority available to others                 */ 
            OS_EXIT_CRITICAL(); 
        } 
        return (err); 
    } 
    OS_EXIT_CRITICAL(); 
    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.