os_task.c

uCOS-II学习资料

/*
*********************************************************************************************************
*                                                uC/OS-II
*                                          The Real-Time Kernel
*                                            TASK MANAGEMENT
*
*                              (c) Copyright 1992-2007, Micrium, Weston, FL
*                                           All Rights Reserved
*
* File    : OS_TASK.C
* By      : Jean J. Labrosse
* Version : V2.86
*
* LICENSING TERMS:
* ---------------
*   uC/OS-II is provided in source form for FREE evaluation, for educational use or for peaceful research.  
* If you plan on using  uC/OS-II  in a commercial product you need to contact Micri祄 to properly license 
* its use in your product. We provide ALL the source code for your convenience and to help you experience 
* uC/OS-II.   The fact that the  source is provided does  NOT  mean that you can use it without  paying a 
* licensing fee.
*********************************************************************************************************
*/

#ifndef  OS_MASTER_FILE
#include <ucos_ii.h>
#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_ERR_NONE            is the call was successful
*              OS_ERR_PRIO_INVALID    if the priority you specify is higher that the maximum allowed
*                                     (i.e. >= OS_LOWEST_PRIO)
*              OS_ERR_PRIO_EXIST      if the new priority already exist.
*              OS_ERR_PRIO            there is no task with the specified OLD priority (i.e. the OLD task does
*                                     not exist.
*              OS_ERR_TASK_NOT_EXIST  if the task is assigned to a Mutex PIP.
*********************************************************************************************************
*/

#if OS_TASK_CHANGE_PRIO_EN > 0
INT8U  OSTaskChangePrio (INT8U oldprio, INT8U newprio)
{
#if (OS_EVENT_EN)
    OS_EVENT  *pevent;
#if (OS_EVENT_MULTI_EN > 0)
    OS_EVENT **pevents;
#endif
#endif
    OS_TCB    *ptcb;
    INT8U      y_new;
    INT8U      x_new;
    INT8U      y_old;
#if OS_LOWEST_PRIO <= 63
    INT8U      bity_new;
    INT8U      bitx_new;
    INT8U      bity_old;
    INT8U      bitx_old;
#else
    INT16U     bity_new;
    INT16U     bitx_new;
    INT16U     bity_old;
    INT16U     bitx_old;
#endif
#if OS_CRITICAL_METHOD == 3
    OS_CPU_SR  cpu_sr = 0;                                  /* Storage for CPU status register         */
#endif


/*$PAGE*/
#if OS_ARG_CHK_EN > 0
    if (oldprio >= OS_LOWEST_PRIO) {
        if (oldprio != OS_PRIO_SELF) {
            return (OS_ERR_PRIO_INVALID);
        }
    }
    if (newprio >= OS_LOWEST_PRIO) {
        return (OS_ERR_PRIO_INVALID);
    }
#endif
    OS_ENTER_CRITICAL();
    if (OSTCBPrioTbl[newprio] != (OS_TCB *)0) {             /* New priority must not already exist     */
        OS_EXIT_CRITICAL();
        return (OS_ERR_PRIO_EXIST);
    }
    if (oldprio == OS_PRIO_SELF) {                          /* See if changing self                    */
        oldprio = OSTCBCur->OSTCBPrio;                      /* Yes, get priority                       */
    }
    ptcb = OSTCBPrioTbl[oldprio];
    if (ptcb == (OS_TCB *)0) {                              /* Does task to change exist?              */
        OS_EXIT_CRITICAL();                                 /* No, can't change its priority!          */
        return (OS_ERR_PRIO);
    }
    if (ptcb == OS_TCB_RESERVED) {                          /* Is task assigned to Mutex               */
        OS_EXIT_CRITICAL();                                 /* No, can't change its priority!          */
        return (OS_ERR_TASK_NOT_EXIST);
    }
#if OS_LOWEST_PRIO <= 63
    y_new                 = (INT8U)(newprio >> 3);          /* Yes, compute new TCB fields             */
    x_new                 = (INT8U)(newprio & 0x07);
    bity_new              = (INT8U)(1 << y_new);
    bitx_new              = (INT8U)(1 << x_new);
#else
    y_new                 = (INT8U)((newprio >> 4) & 0x0F);
    x_new                 = (INT8U)( newprio & 0x0F);
    bity_new              = (INT16U)(1 << y_new);
    bitx_new              = (INT16U)(1 << x_new);
#endif

    OSTCBPrioTbl[oldprio] = (OS_TCB *)0;                    /* Remove TCB from old priority            */
    OSTCBPrioTbl[newprio] =  ptcb;                          /* Place pointer to TCB @ new priority     */
    y_old                 =  ptcb->OSTCBY;
    bity_old              =  ptcb->OSTCBBitY;
    bitx_old              =  ptcb->OSTCBBitX;
    if ((OSRdyTbl[y_old] &   bitx_old) != 0) {              /* If task is ready make it not            */
         OSRdyTbl[y_old] &= ~bitx_old;
         if (OSRdyTbl[y_old] == 0) {
             OSRdyGrp &= ~bity_old;
         }
         OSRdyGrp        |= bity_new;                       /* Make new priority ready to run          */
         OSRdyTbl[y_new] |= bitx_new;
    }

#if (OS_EVENT_EN)
    pevent = ptcb->OSTCBEventPtr;
    if (pevent != (OS_EVENT *)0) {
        pevent->OSEventTbl[y_old] &= ~bitx_old;             /* Remove old task prio from wait list     */
        if (pevent->OSEventTbl[y_old] == 0) {
            pevent->OSEventGrp    &= ~bity_old;
        }
        pevent->OSEventGrp        |= bity_new;              /* Add    new task prio to   wait list     */
        pevent->OSEventTbl[y_new] |= bitx_new;
    }
#if (OS_EVENT_MULTI_EN > 0)
    if (ptcb->OSTCBEventMultiPtr != (OS_EVENT **)0) {
        pevents =  ptcb->OSTCBEventMultiPtr;
        pevent  = *pevents;
        while (pevent != (OS_EVENT *)0) {
            pevent->OSEventTbl[y_old] &= ~bitx_old;         /* Remove old task prio from wait lists    */
            if (pevent->OSEventTbl[y_old] == 0) {
                pevent->OSEventGrp    &= ~bity_old;
            }
            pevent->OSEventGrp        |= bity_new;          /* Add    new task prio to   wait lists    */
            pevent->OSEventTbl[y_new] |= bitx_new;
            pevents++;
            pevent                     = *pevents;
        }
    }
#endif
#endif

    ptcb->OSTCBPrio = newprio;                              /* Set new task priority                   */
    ptcb->OSTCBY    = y_new;
    ptcb->OSTCBX    = x_new;
    ptcb->OSTCBBitY = bity_new;
    ptcb->OSTCBBitX = bitx_new;
    OS_EXIT_CRITICAL();
    if (OSRunning == OS_TRUE) {
        OS_Sched();                                         /* Find new highest priority task          */
    }
    return (OS_ERR_NONE);
}
#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
*
*              p_arg    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 'p_arg' as follows:
*
*                           void Task (void *p_arg)
*                           {
*                               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_ERR_NONE             if the function was successful.
*              OS_PRIO_EXIT            if the task priority already exist
*                                      (each task MUST have a unique priority).
*              OS_ERR_PRIO_INVALID     if the priority you specify is higher that the maximum allowed
*                                      (i.e. >= OS_LOWEST_PRIO)
*              OS_ERR_TASK_CREATE_ISR  if you tried to create a task from an ISR.
*********************************************************************************************************
*/

#if OS_TASK_CREATE_EN > 0
INT8U  OSTaskCreate (void (*task)(void *p_arg), void *p_arg, OS_STK *ptos, INT8U prio)
{
    OS_STK    *psp;
    INT8U      err;
#if OS_CRITICAL_METHOD == 3                  /* Allocate storage for CPU status register               */
    OS_CPU_SR  cpu_sr = 0;
#endif



#if OS_ARG_CHK_EN > 0
    if (prio > OS_LOWEST_PRIO) {             /* Make sure priority is within allowable range           */
        return (OS_ERR_PRIO_INVALID);
    }
#endif
    OS_ENTER_CRITICAL();
    if (OSIntNesting > 0) {                  /* Make sure we don't create the task from within an ISR  */
        OS_EXIT_CRITICAL();
        return (OS_ERR_TASK_CREATE_ISR);
    }
    if (OSTCBPrioTbl[prio] == (OS_TCB *)0) { /* Make sure task doesn't already exist at this priority  */
        OSTCBPrioTbl[prio] = OS_TCB_RESERVED;/* Reserve the priority to prevent others from doing ...  */
                                             /* ... the same thing until task is created.              */
        OS_EXIT_CRITICAL();
        psp = OSTaskStkInit(task, p_arg, ptos, 0);              /* Initialize the task's stack         */
        err = OS_TCBInit(prio, psp, (OS_STK *)0, 0, 0, (void *)0, 0);
        if (err == OS_ERR_NONE) {
            if (OSRunning == OS_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_ERR_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
*
*              p_arg     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 'p_arg' as follows:
*
*                            void Task (void *p_arg)
*                            {
*                                for (;;) {