os_cpu_c.c

讲UC/OS的书

/*
*********************************************************************************************************
*                                               uC/OS-II
*                                         The Real-Time Kernel
*
*                        (c) Copyright 1992-1998, Jean J. Labrosse, Plantation, FL
*                                          All Rights Reserved
*                        (c) Copyright ARM Limited 1999.  All rights reserved.
*
*                                          ARM Specific code
*
*
* File : OS_CPU_C.C
*********************************************************************************************************
*/

#define  OS_CPU_GLOBALS
#include "includes.h"

/*与CPU硬件及编译器相关的代码,在UCOS_II.H中声明*/
SYS_Stk sys_stk_info;
SYS_Stk *Sys_sp;

/*任务堆栈初始化*/
void *OSTaskStkInit (void (*task)(void *pd), void *pdata, void *ptos, INT16U opt)
{
    unsigned int *stk;

    opt    = opt;                           /* 'opt' is not used, prevent warning                      */
    stk    = (unsigned int *)ptos;          /* Load stack pointer 当前的栈底                                      */

    /* build a context for the new task */
    *--stk = opt;
    *--stk = (unsigned int) task;       /* opt maybe need pc */
    
    *--stk = (unsigned int) task;       /* pc */
    *--stk = 0x0000;    /* Y */
    *--stk = 0x0000;    /* X */
    *--stk = 0;                         /* A,B */
    ((INT8U *)stk)--;
    *(INT8U *)stk=(INT8U)(0x00);/*CCR*/
    //((INT8U *)stk)--;
    //*(INT8U *)stk=*(INT8U *)pdata;/*PPAGE*//*在建立任务时 需要利用pdata这个参数将PPAGE信息传入*/
    return ((void *)stk);
}


/*优先级最高的就绪任务开始运行*/
void OSStartHighRdy(void){

    OSRunning=1;
    Sys_sp=&sys_stk_info;//指向SYS_Stk这个结构体
    asm{
      ldx Sys_sp
      sts 0,x   //save sp to Sys_sp
    
      ldx  OSTCBCur
      lds 0,x
      //pula /*出栈并赋值给A*/
      //staa $30/*把A的值传递给 PPAGE(0x30)*/
      //nop
      rti/*出栈顺序CCR,B,A,X,Y,PC*/ 
    }
}

/*任务级任务切换函数*/
void OSCtxSw(void){
    asm{
      pshy
      pshx
      pshd
      pshc				//模拟中断保存现场 PC在Call OSCtxSw()已经保存
      //ldaa $30  //save PPAGE to A
      //psha      //save A to stack
      
      ldx OSTCBCur
      sts 0,x   //save sp to OSTCBCur
    }
    
    OSTCBCur = OSTCBHighRdy;
    OSPrioCur = OSPrioHighRdy;
    asm{
      ldx OSTCBCur   //Get the new OSTCBCur  to x
      lds 0,x        //load x to sp
      //pula
      //staa $30
      rti
    }
}

/*中断级任务切换函数*/
void OSIntCtxSw(void){
    //从系统堆栈切换回任务堆栈
    asm{
      ldx Sys_sp
      ins
      ins
      ins
      ins				//调整堆栈深度OSIntExit 2byte  OSIntCtxSw 2byte
      sts 0,x   //save sp to Sys_sp
    }
    
    //进入中断时系统已经在被打断任务的堆栈中保存了信息
    OSTCBCur = OSTCBHighRdy;
    OSPrioCur = OSPrioHighRdy;
    asm{
      ldx OSTCBCur	  //Get the new OSTCBCur  to x
      lds 0,x					//load x to sp
      //pula						//PPAGE 在中断调用时已经入栈
      //staa $30
      //nop 
      rti
    }
}

/*$PAGE*/
#if OS_CPU_HOOKS_EN
/*
*********************************************************************************************************
*                                          TASK CREATION HOOK
*
* Description: This function is called when a task is created.
*
* Arguments  : ptcb   is a pointer to the task control block of the task being created.
*
* Note(s)    : 1) Interrupts are disabled during this call.
*********************************************************************************************************
*/
void OSTaskCreateHook (OS_TCB *ptcb)
{
    ptcb = ptcb;                       /* Prevent compiler warning                                     */
}


/*
*********************************************************************************************************
*                                           TASK DELETION HOOK
*
* Description: This function is called when a task is deleted.
*
* Arguments  : ptcb   is a pointer to the task control block of the task being deleted.
*
* Note(s)    : 1) Interrupts are disabled during this call.
*********************************************************************************************************
*/
void OSTaskDelHook (OS_TCB *ptcb)
{
    ptcb = ptcb;                       /* Prevent compiler warning                                     */
}

/*
*********************************************************************************************************
*                                           TASK SWITCH HOOK
*
* Description: This function is called when a task switch is performed.  This allows you to perform other
*              operations during a context switch.
*
* Arguments  : none
*
* Note(s)    : 1) Interrupts are disabled during this call.
*              2) It is assumed that the global pointer 'OSTCBHighRdy' points to the TCB of the task that
*                 will be 'switched in' (i.e. the highest priority task) and, 'OSTCBCur' points to the 
*                 task being switched out (i.e. the preempted task).
*********************************************************************************************************
*/
void OSTaskSwHook (void)
{
}

/*
*********************************************************************************************************
*                                           STATISTIC TASK HOOK
*
* Description: This function is called every second by uC/OS-II's statistics task.  This allows your 
*              application to add functionality to the statistics task.
*
* Arguments  : none
*********************************************************************************************************
*/
void OSTaskStatHook (void)
{
}

/*
*********************************************************************************************************
*                                               TICK HOOK
*
* Description: This function is called every tick.
*
* Arguments  : none
*
* Note(s)    : 1) Interrupts may or may not be ENABLED during this call.
*********************************************************************************************************
*/

void OSTimeTickHook (void)
{
}
#endif