os_task.c

这是一个uC/OS-II For S3C44B0x的移植项目源代码．可以在uCOSV252.exe上运行

/*
*********************************************************************************************************
*                                                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 "includes.h"
#endif

/*
*********************************************************************************************************
*                                        LOCAL FUNCTION PROTOTYPES
*********************************************************************************************************
*/


static  void  OSDummy(void);

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

static void  OSDummy (void)
{
}

/*$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.
*********************************************************************************************************
*/

#if OS_TASK_CHANGE_PRIO_EN
INT8U OSTaskChangePrio (INT8U oldprio, INT8U newprio)
{
    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);
    }
    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                   */
        }
        if ((ptcb = OSTCBPrioTbl[oldprio]) != (OS_TCB *)0) {    /* Task to change must exist           */
            OSTCBPrioTbl[oldprio] = (OS_TCB *)0;                /* Remove TCB from old priority        */
            if (OSRdyTbl[ptcb->OSTCBY] & ptcb->OSTCBBitX) {     /* If task is ready make it not ready  */
                if ((OSRdyTbl[ptcb->OSTCBY] &= ~ptcb->OSTCBBitX) == 0) {
                    OSRdyGrp &= ~ptcb->OSTCBBitY;
                }
                OSRdyGrp    |= bity;                            /* Make new priority ready to run      */
                OSRdyTbl[y] |= bitx;
            } else {
                if ((pevent = ptcb->OSTCBEventPtr) != (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;
                }
            }
            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();
            OSSched();                                          /* 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
INT8U OSTaskCreate (void (*task)(void *pd), void *pdata, OS_STK *ptos, INT8U prio)
{
    void   *psp;
    INT8U   err;


    if (prio > OS_LOWEST_PRIO) {             /* Make sure priority is within allowable range           */
        return (OS_PRIO_INVALID);
    }
    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 = (void *)OSTaskStkInit(task, pdata, ptos, 0); /* Initialize the task's stack              */
        err = OSTCBInit(prio, psp, (void *)0, 0, 0, (void *)0, 0);         
        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*/
/*
*********************************************************************************************************
*                                     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.