/*
*********************************************************************************************************
*                                               uC/OS-II
*                                         The Real-Time Kernel
*
*                         (c) Copyright 1992-2002, Jean J. Labrosse, Weston, FL
*                                          All Rights Reserved
*
*
*                                       80x86/80x88 Specific code
*                                          LARGE MEMORY MODEL
*
*                                          Borland C/C++ V4.51
*
* File         : OS_CPU_C.C
* By           : Jean J. Labrosse
*********************************************************************************************************
*/

#define  OS_CPU_GLOBALS
#include "uCOS_II.H"

/*
*********************************************************************************************************
*                                        INITIALIZE A TASK'S STACK
*
* Description: This function is called by either OSTaskCreate() or OSTaskCreateExt() to initialize the
*              stack frame of the task being created.  This function is highly processor specific.
*
* Arguments  : task          is a pointer to the task code
*
*              ppdata         is a pointer to a user supplied data area that will be passed to the task
*                            when the task first executes.
*
*              ptos          is a pointer to the top of stack.  It is assumed that 'ptos' points to
*                            a 'free' entry on the task stack.  If OS_STK_GROWTH is set to 1 then 
*                            'ptos' will contain the HIGHEST valid address of the stack.  Similarly, if
*                            OS_STK_GROWTH is set to 0, the 'ptos' will contains the LOWEST valid address
*                            of the stack.
*
*              opt           specifies options that can be used to alter the behavior of OSTaskStkInit().
*                            (see uCOS_II.H for OS_TASK_OPT_???).
*
* Returns    : Always returns the location of the new top-of-stack' once the processor registers have
*              been placed on the stack in the proper order.
*
* Note(s)    : Interrupts are enabled when your task starts executing. You can change this by setting the
*              PSW to 0x0002 instead.  In this case, interrupts would be disabled upon task startup.  The
*              application code would be responsible for enabling interrupts at the beginning of the task
*              code.  You will need to modify OSTaskIdle() and OSTaskStat() so that they enable 
*              interrupts.  Failure to do this will make your system crash!
*********************************************************************************************************
*/

OS_STK *OSTaskStkInit (void (*task)(void *pd) OS_REENTRANT, void *ppdata, OS_STK *ptos, INT16U opt) OS_REENTRANT
{    
    OS_STK *stk;

    ppdata = ppdata;
    opt    = opt;                               //opt沒被用到，保留此語句防止告警產生    
    stk    = ptos;                              //用戶堆棧最低有效地址
    *stk++ = 15;                                //用戶堆棧長度
    *stk++ = (INT16U)task & 0xFF;               //任務地址低8位
    *stk++ = (INT16U)task >> 8;                 //任務地址高8位    
    *stk++ = 0x0A;                              //ACC
    *stk++ = 0x0B;                              //B
    *stk++ = 0x00;                              //DPH
    *stk++ = 0x00;                              //DPL
    *stk++ = 0x00;                              //PSW
    *stk++ = 0x00;                              //R0
    
	//R3、R2、R1用于傳遞任務參數ppdata，其中R3代表存儲器類型，R2為高字節偏移，R1為低字節位移。
	//通過分析KEIL匯編，了解到任務的void *ppdata參數恰好是用R3、R2、R1傳遞，不是通過虛擬堆棧。
    *stk++ = (INT16U)ppdata & 0xFF;             //R1
    *stk++ = (INT16U)ppdata >> 8;               //R2
    *stk++ = 0x01;                              //R3  因為我用的全是XDATA，所以存儲器類型固定為1，見C51.PDF第178頁說明。

    *stk++ = 0x04;                              //R4
    *stk++ = 0x05;                              //R5
    *stk++ = 0x06;                              //R6
    *stk++ = 0x07;                              //R7
                                                //不用保存SP，任務切換時根據用戶堆棧長度計算得出。    
    *stk++ = (INT16U) (ptos+MaxStkSize) >> 8;   //?C_XBP 仿真堆棧指針高8位
    *stk++ = (INT16U) (ptos+MaxStkSize) & 0xFF; //?C_XBP 仿真堆棧指針低8位
        
    return ((void *)ptos);
}

/*
*********************************************************************************************************
*                                       OS INITIALIZATION HOOK
*                                            (BEGINNING)
*
* Description: This function is called by OSInit() at the beginning of OSInit().
*
* Arguments  : none
*
* Note(s)    : 1) Interrupts should be disabled during this call.
*********************************************************************************************************
*/
#if OS_CPU_HOOKS_EN > 0 && OS_VERSION > 203
void  OSInitHookBegin (void) OS_REENTRANT
{
}
#endif

/*
*********************************************************************************************************
*                                       OS INITIALIZATION HOOK
*                                               (END)
*
* Description: This function is called by OSInit() at the end of OSInit().
*
* Arguments  : none
*
* Note(s)    : 1) Interrupts should be disabled during this call.
*********************************************************************************************************
*/
#if OS_CPU_HOOKS_EN > 0 && OS_VERSION > 203
void  OSInitHookEnd (void) OS_REENTRANT
{
}
#endif

/*
*********************************************************************************************************
*                                          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.
*********************************************************************************************************
*/
#if OS_CPU_HOOKS_EN > 0 
void  OSTaskCreateHook (OS_TCB *ptcb) OS_REENTRANT
{
    ptcb = ptcb;                       /* Prevent compiler warning                                     */
}
#endif


/*
*********************************************************************************************************
*                                           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.
*********************************************************************************************************
*/
#if OS_CPU_HOOKS_EN > 0 && OS_TASK_DEL_EN > 0
void  OSTaskDelHook (OS_TCB *ptcb) OS_REENTRANT
{
    ptcb = ptcb;                       /* Prevent compiler warning                                     */
}
#endif

/*
*********************************************************************************************************
*                                             IDLE TASK HOOK
*
* Description: This function is called by the idle task.  This hook has been added to allow you to do  
*              such things as STOP the CPU to conserve power.
*
* Arguments  : none
*
* Note(s)    : 1) Interrupts are enabled during this call.
*********************************************************************************************************
*/
#if OS_CPU_HOOKS_EN > 0 && OS_VERSION >= 251
void  OSTaskIdleHook (void) OS_REENTRANT
{
}
#endif

/*
*********************************************************************************************************
*                                           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
*********************************************************************************************************
*/

#if OS_CPU_HOOKS_EN > 0 && OS_TASK_STAT_EN > 0
void  OSTaskStatHook (void) OS_REENTRANT
{
}
#endif

/*
*********************************************************************************************************
*                                           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) OS_REENTRANT
{
}
#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) OS_REENTRANT
{
    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) OS_REENTRANT
{
}
#endif

/* 
*********************************************************************************************************
* ucOS-II系統時鐘初始化,中斷處理程序,使用51定時器0
*********************************************************************************************************
*/
void OSTickInit(void)
{
	TMOD &= 0xf0;
    TMOD |= 0x01;
    TR0  = 1;
    ET0  = 1;
}
void OSTickISR(void) interrupt 1
{
    OSIntEnter();					// Must be called first at every hardware interrupt entry point 
    TH0=0x70;    					//MCS51定時器方式1，必須在發生中斷時，重新賦值并再次啟動計時
    TL0=0;            				//Tick=50次/秒(即0.02秒/次)，晶振22.1184M
   	OSTimeTick();					// Must be called during tick isr 
   	OSIntExit();					// Must be called finally at every hardware interupt exit point 
}