os_core.c

使用mega8和iccavr编译器的一段ucos操作系统程序

#ifndef  OS_MASTER_FILE
#define  OS_GLOBALS
#include "includes.h"
#endif

/*
*********************************************************************************************************
*                                         LOCAL GLOBAL VARIABLES
*********************************************************************************************************
*/
                                       
static  INT8U        OSIntExitY;               /* Variable used by 'OSIntExit' to prevent using locals */
static  OS_STK       OSTaskIdleStk[OS_TASK_IDLE_STK_SIZE];       /* Idle       task stack              */

#if     OS_TASK_STAT_EN
static  OS_STK       OSTaskStatStk[OS_TASK_STAT_STK_SIZE];      /* Statistics task stack               */
#endif

static  OS_TCB       OSTCBTbl[OS_MAX_TASKS + OS_N_SYS_TASKS];   /* Table of TCBs                       */

/*$PAGE*/
/*
*********************************************************************************************************
*                              MAPPING TABLE TO MAP BIT POSITION TO BIT MASK
*
* Note: Index into table is desired bit position, 0..7
*       Indexed value corresponds to bit mask
*********************************************************************************************************
*/

INT8U const OSMapTbl[]   = {0x01, 0x02, 0x04, 0x08, 0x10, 0x20, 0x40, 0x80};

/*
*********************************************************************************************************
*                                       PRIORITY RESOLUTION TABLE
*
* Note: Index into table is bit pattern to resolve highest priority
*       Indexed value corresponds to highest priority bit position (i.e. 0..7)
*********************************************************************************************************
*/

INT8U const OSUnMapTbl[] = {
    0, 0, 1, 0, 2, 0, 1, 0, 3, 0, 1, 0, 2, 0, 1, 0,
    4, 0, 1, 0, 2, 0, 1, 0, 3, 0, 1, 0, 2, 0, 1, 0,
    5, 0, 1, 0, 2, 0, 1, 0, 3, 0, 1, 0, 2, 0, 1, 0,
    4, 0, 1, 0, 2, 0, 1, 0, 3, 0, 1, 0, 2, 0, 1, 0,
    6, 0, 1, 0, 2, 0, 1, 0, 3, 0, 1, 0, 2, 0, 1, 0,
    4, 0, 1, 0, 2, 0, 1, 0, 3, 0, 1, 0, 2, 0, 1, 0,
    5, 0, 1, 0, 2, 0, 1, 0, 3, 0, 1, 0, 2, 0, 1, 0,
    4, 0, 1, 0, 2, 0, 1, 0, 3, 0, 1, 0, 2, 0, 1, 0,
    7, 0, 1, 0, 2, 0, 1, 0, 3, 0, 1, 0, 2, 0, 1, 0,
    4, 0, 1, 0, 2, 0, 1, 0, 3, 0, 1, 0, 2, 0, 1, 0,
    5, 0, 1, 0, 2, 0, 1, 0, 3, 0, 1, 0, 2, 0, 1, 0,
    4, 0, 1, 0, 2, 0, 1, 0, 3, 0, 1, 0, 2, 0, 1, 0,
    6, 0, 1, 0, 2, 0, 1, 0, 3, 0, 1, 0, 2, 0, 1, 0,
    4, 0, 1, 0, 2, 0, 1, 0, 3, 0, 1, 0, 2, 0, 1, 0,
    5, 0, 1, 0, 2, 0, 1, 0, 3, 0, 1, 0, 2, 0, 1, 0,
    4, 0, 1, 0, 2, 0, 1, 0, 3, 0, 1, 0, 2, 0, 1, 0
};

/*$PAGE*/
/*
*********************************************************************************************************
*                                             INITIALIZATION
*
* Description: This function is used to initialize the internals of uC/OS-II and MUST be called prior to
*              creating any uC/OS-II object and, prior to calling OSStart().
*
* Arguments  : none
*
* Returns    : none
*********************************************************************************************************
*/

void OSInit (void)
{
    INT16U i;


    OSTime        = 0L;                                    /* Clear the 32-bit system clock            */
    OSIntNesting  = 0;                                     /* Clear the interrupt nesting counter      */
    OSLockNesting = 0;                                     /* Clear the scheduling lock counter        */
#if OS_TASK_CREATE_EN  || OS_TASK_CREATE_EXT_EN || OS_TASK_DEL_EN
    OSTaskCtr     = 0;                                     /* Clear the number of tasks                */
#endif
    OSRunning     = FALSE;                                 /* Indicate that multitasking not started   */
    OSIdleCtr     = 0L;                                    /* Clear the 32-bit idle counter            */

    OSCtxSwCtr    = 0;                                     /* Clear the context switch counter         */
    OSRdyGrp      = 0;                                     /* Clear the ready list                     */
    for (i = 0; i < OS_RDY_TBL_SIZE; i++) {
        OSRdyTbl[i] = 0;
    }
                
    OSPrioCur     = 0;
    OSPrioHighRdy = 0;                                           
    OSTCBHighRdy  = (OS_TCB *)0;                                 /* TCB Initialization                 */
    OSTCBCur      = (OS_TCB *)0;
    OSTCBList     = (OS_TCB *)0;
    for (i = 0; i < (OS_LOWEST_PRIO + 1); i++) {                 /* Clear the priority table           */
        OSTCBPrioTbl[i] = (OS_TCB *)0;
    }
    for (i = 0; i < (OS_MAX_TASKS + OS_N_SYS_TASKS - 1); i++) {  /* Init. list of free TCBs            */
        OSTCBTbl[i].OSTCBNext = &OSTCBTbl[i + 1];
    }
    OSTCBTbl[OS_MAX_TASKS + OS_N_SYS_TASKS - 1].OSTCBNext = (OS_TCB *)0;    /* Last OS_TCB             */
    OSTCBFreeList                                         = &OSTCBTbl[0];

#if OS_MAX_EVENTS >= 2
    for (i = 0; i < (OS_MAX_EVENTS - 1); i++) {            /* Init. list of free EVENT control blocks  */
        OSEventTbl[i].OSEventPtr = (OS_EVENT *)&OSEventTbl[i + 1];
    }
    OSEventTbl[OS_MAX_EVENTS - 1].OSEventPtr = (OS_EVENT *)0;
    OSEventFreeList                          = &OSEventTbl[0];    
#endif

#if OS_STK_GROWTH == 1
    OSTaskCreate(OSTaskIdle, (void *)0, &OSTaskIdleStk[OS_TASK_IDLE_STK_SIZE - 1], OS_IDLE_PRIO);
#else
    OSTaskCreate(OSTaskIdle, (void *)0, &OSTaskIdleStk[0], OS_IDLE_PRIO);
#endif

}
/*$PAGE*/
/*
*********************************************************************************************************
*                                               EXIT ISR
*
* Description: This function is used to notify uC/OS-II that you have completed serviving an ISR.  When 
*              the last nested ISR has completed, uC/OS-II will call the scheduler to determine whether
*              a new, high-priority task, is ready to run.
*
* Arguments  : none
*
* Returns    : none
*
* Notes      : 1) You MUST invoke OSIntEnter() and OSIntExit() in pair.  In other words, for every call
*                 to OSIntEnter() at the beginning of the ISR you MUST have a call to OSIntExit() at the
*                 end of the ISR.
*              2) Rescheduling is prevented when the scheduler is locked (see OSSchedLock())
*********************************************************************************************************
*/

void OSIntExit (void)
{
    OS_ENTER_CRITICAL();
    if ((--OSIntNesting | OSLockNesting) == 0) { /* Reschedule only if all ISRs completed & not locked */
        OSIntExitY    = OSUnMapTbl[OSRdyGrp];
        OSPrioHighRdy = (INT8U)((OSIntExitY << 3) + OSUnMapTbl[OSRdyTbl[OSIntExitY]]);
        if (OSPrioHighRdy != OSPrioCur) {        /* No context switch if current task is highest ready */
            OSTCBHighRdy  = OSTCBPrioTbl[OSPrioHighRdy];
            OSCtxSwCtr++;                        /* Keep track of the number of context switches       */
            OSIntCtxSw();                        /* Perform interrupt level context switch             */
        }
    }
    OS_EXIT_CRITICAL();
}
/*$PAGE*/
/*
*********************************************************************************************************
*                                              SCHEDULER
*
* Description: This function is called by other uC/OS-II services to determine whether a new, high
*              priority task has been made ready to run.  This function is invoked by TASK level code
*              and is not used to reschedule tasks from ISRs (see OSIntExit() for ISR rescheduling).
*
* Arguments  : none
*
* Returns    : none
*
* Notes      : 1) This function is INTERNAL to uC/OS-II and your application should not call it.
*              2) Rescheduling is prevented when the scheduler is locked (see OSSchedLock())
*********************************************************************************************************
*/

void OSSched (void)
{
    INT8U y;


    OS_ENTER_CRITICAL();
    if ((OSLockNesting | OSIntNesting) == 0) {   /* Task scheduling must be enabled and not ISR level  */
        y             = OSUnMapTbl[OSRdyGrp];    /* Get pointer to highest priority task ready to run  */
        OSPrioHighRdy = (INT8U)((y << 3) + OSUnMapTbl[OSRdyTbl[y]]);
        if (OSPrioHighRdy != OSPrioCur) {         /* No context switch if current task is highest ready */
            OSTCBHighRdy = OSTCBPrioTbl[OSPrioHighRdy];
            OSCtxSwCtr++;                        /* Increment context switch counter                   */
            OS_TASK_SW();                        /* Perform a context switch                           */