/***********************************************************************************************************                                                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_ENINT8U 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_ENINT8U 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.