os_cpu_c.c

《嵌入式系统-使用HCS12微控制器的设计与应用》在CodeWarrior开发环境下的源程序。

    // SCISend1(*(INT8U *)pdata);    
    stk  = (INT16U *)ptos;               //加载堆栈指针，空两个字节 
    *--stk = opt;                        //该一个字节为特殊选项，存用户参数
    *--stk = (INT16U)task;				       //PC入栈
    *--stk = (INT16U)(0x1122);	         //Y
    *--stk = (INT16U)(0x3344);			     //X    
    ((INT8U *)stk)--;
    *(INT8U *)stk = (INT8U)(((INT16U)pdata)>>8); //A
    ((INT8U *)stk)--;
    *(INT8U *)stk = (INT8U)(pdata);	     //B
    ((INT8U *)stk)--;
    *(INT8U *)stk = (INT8U)(0x00);       //CCR
    ((INT8U *)stk)--;
    *(INT8U *)stk = *(INT8U *)pdata;     //只有PPAGE一个内容  					   	  	
  	return ((void *)stk); 
}

/*$PAGE*/
/*
*********************************************************************************************************
*                        INITIALIZE A TASK'S STACK FOR FLOATING POINT EMULATION
*
* Description: This function MUST be called BEFORE calling either OSTaskCreate() or OSTaskCreateExt() in
*              order to initialize the task's stack to allow the task to use the Borland floating-point 
*              emulation.  The returned pointer MUST be used in the task creation call.
*
*              Ex.:   OS_STK TaskStk[1000];
*
*
*                     void main (void)
*                     {
*                         OS_STK *ptos;
*                         OS_STK *pbos;
*                         INT32U  size;
*
*
*                         OSInit();
*                         .
*                         .
*                         ptos  = &TaskStk[999];
*                         pbos  = &TaskStk[0];
*                         psize = 1000;
*                         OSTaskStkInit_FPE_x86(&ptos, &pbos, &size);
*                         OSTaskCreate(Task, (void *)0, ptos, 10);
*                         .
*                         .
*                         OSStart();
*                     }
*
* Arguments  : pptos         is the pointer to the task's top-of-stack pointer which would be passed to 
*                            OSTaskCreate() or OSTaskCreateExt().
*
*              ppbos         is the pointer to the new bottom of stack pointer which would be passed to
*                            OSTaskCreateExt().
*
*              psize         is a pointer to the size of the stack (in number of stack elements).  You 
*                            MUST allocate sufficient stack space to leave at least 384 bytes for the 
*                            floating-point emulation.
*
* Returns    : The new size of the stack once memory is allocated to the floating-point emulation.
*
* Note(s)    : 1) _SS  is a Borland 'pseudo-register' and returns the contents of the Stack Segment (SS)
*              2) The pointer to the top-of-stack (pptos) will be modified so that it points to the new
*                 top-of-stack.
*              3) The pointer to the bottom-of-stack (ppbos) will be modified so that it points to the new
*                 bottom-of-stack.
*              4) The new size of the stack is adjusted to reflect the fact that memory was reserved on
*                 the stack for the floating-point emulation.
*********************************************************************************************************
*/

/*$PAGE*/
//void  OSTaskStkInit_FPE_x86 (OS_STK **pptos, OS_STK **ppbos, INT32U *psize)
//{
//    INT32U   lin_tos;                                 /* 'Linear' version of top-of-stack    address   */
//    INT32U   lin_bos;                                 /* 'Linear' version of bottom-of-stack address   */
//    INT16U   seg;
//    INT16U   off;
//    INT32U   bytes;
//    seg      = FP_SEG(*pptos);                        /* Decompose top-of-stack pointer into seg:off   */
//    off      = FP_OFF(*pptos);
//    lin_tos  = ((INT32U)seg << 4) + (INT32U)off;      /* Convert seg:off to linear address             */
//    bytes    = *psize * sizeof(OS_STK);               /* Determine how many bytes for the stack        */
//    lin_bos  = (lin_tos - bytes + 15) & 0xFFFFFFF0L;  /* Ensure paragraph alignment for BOS            */   
//    seg      = (INT16U)(lin_bos >> 4);                /* Get new 'normalized' segment                  */
//    *ppbos   = (OS_STK *)MK_FP(seg, 0x0000);          /* Create 'normalized' BOS pointer               */
//    memcpy(*ppbos, MK_FP(_SS, 0), 384);               /* Copy FP emulation memory to task's stack      */
//    bytes    = bytes - 16;                            /* Loose 16 bytes because of alignment           */
//    *pptos   = (OS_STK *)MK_FP(seg, (INT16U)bytes);   /* Determine new top-of-stack                    */
//    *ppbos   = (OS_STK *)MK_FP(seg, 384);             /* Determine new bottom-of-stack                 */
//    bytes    = bytes - 384;
//    *psize   = bytes / sizeof(OS_STK);                /* Determine new stack size                      */
//}

/*$PAGE*/
/*
*********************************************************************************************************
*                                           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).
*********************************************************************************************************
*/
#if OS_CPU_HOOKS_EN > 0 
void  OSTaskSwHook (void)
{
}
#endif

/*
*********************************************************************************************************
*                                           OSTCBInit() HOOK
*
* Description: This function is called by OS_TCBInit() after setting up most of the TCB.
*
* Arguments  : ptcb    is a pointer to the TCB of the task being created.
*
* Note(s)    : 1) Interrupts may or may not be ENABLED during this call.
*********************************************************************************************************
*/
#if OS_CPU_HOOKS_EN > 0 && OS_VERSION > 203
void  OSTCBInitHook (OS_TCB *ptcb)
{
    ptcb = ptcb;                                           /* Prevent Compiler warning                 */
}
#endif


/*
*********************************************************************************************************
*                                               TICK HOOK
*
* Description: This function is called every tick.
*
* Arguments  : none
*
* Note(s)    : 1) Interrupts may or may not be ENABLED during this call.
*********************************************************************************************************
*/
#if OS_CPU_HOOKS_EN > 0 
void  OSTimeTickHook (void)
{
}
#endif

//OSStartHighRdy:让优先级最高的任务运行函数--------------------------------*
//功  能:让优先级最高的就绪态任务开始运行                                  *
//参  数:无                                                                *
//返  回:无                                                                *
//-------------------------------------------------------------------------*
void OSStartHighRdy(void) 
{
    OSTaskSwHook();   
    OSRunning = 1;
	  asm{
        ldx OSTCBCur  //将TCB的地址给X
        lds 0,X       //将值给SP
        pula
        staa $30      //恢复页面寄存器
        nop           //延时
        rti
	     }
}

//OSIntCtxSw:中断级任务切换函数--------------------------------------------*
//功  能:如果在中断服务结束时，中断中激活了更高优先级的任务，则调用该函数  *
//参  数:无                                                                *
//返  回:无                                                                *
//-------------------------------------------------------------------------*
void OSIntCtxSw(void) 
{
    OSTaskSwHook();
    OSTCBCur = OSTCBHighRdy;       //Change OSTCBCur and OSPrioCur
    OSPrioCur = OSPrioHighRdy;
    asm{
        ldx OSTCBCur		           //get the new task's TCB's address
        lds 0,x
        pula 
        staa $30
        nop			                   //retore ppage from stack
        rti
       }
}