os_cpu_c.c

uCOS2嵌入式操作系统源码

//-------------  2006-12-20 19:06  添加
void * OSTaskStkInit(  void ( * task )(void * pd),
                       void * ppdata,void * ptos,
                       INT16U opt
                    ) reentrant
{
	OS_STK * stk;
	ppdata = ppdata;
	opt = opt;              // opt没用到，防止警告
	stk = (OS_STK *)ptos;   // 用户堆栈最低有效地址
	*stk++ = 15;            // 用户堆栈长度
	*stk++ = (INT16U)task & 0xff;  // 任务地址低8位
	*stk++ = (INT16U)task >> 8;    // 任务地址高8位
	*stk++ = 0x00;          // PSW
	*stk++ = 0x0A;          // ACC
	*stk++ = 0x0B;          // B
	*stk++ = 0x00;          // DPL
	*stk++ = 0x00;          // DPH
	*stk++ = 0x00;          // R0
	
/*R3、R2、R1用于传递任务参数ppdata，其中R3代表存储器类型，R2为高字节偏移，R1为低字节偏移
  通过分析Keil汇编，了解到任务的void ppdata参数恰好是用R3、R2、R1传递，不是通过虚拟堆栈*/
  
  *stk++ = (INT16U)ppdata & 0xff;     // R1
  *stk++ = (INT16U)ppdata >> 8;       // R2
  *stk++ = 0x01;                      // R3
  *stk++ = 0x04;                      // R4
  *stk++ = 0x05;                      // R5
  *stk++ = 0x06;                      // R6
  *stk++ = 0x07;                      // R7
  
  //不用保存SP,任务切换时根据用户堆栈长度计算得出
  *stk++ = (INT16U)(ptos + MaxStkSize) >> 8;    //堆栈映像指针高8位
  *stk++ = (INT16U)(ptos + MaxStkSize) & 0xff;  //堆栈映像指针低8位
  return ((void *)ptos);
}

void InitTime0(void)  reentrant
{
	TMOD = TMOD & 0xf0;
	TMOD = TMOD | 0x01;  // 模式1（16位定时器），仅受TR0控制
	TH0 = 0x70;          // 定义Tick = 50 次/秒
	TL0 = 0x00;
	//ET0 = 1;   // 允许T0中断，此时EAV=0(缺省值)，中断还不会发生，满足在OSStart()前不产生中断的要求
	TR0 = 1;
}









/*$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