#include "INCLUDES.H"


OS_STK *OSTaskStkInit (void (*task)(void *pd), void *pdata, OS_STK *ptos, INT16U opt)
{
    INT32U *stk;							//console 下寄存器為32位寬
	
	
    opt    = opt;                           /* 'opt' is not used, prevent warning                      */
    stk    = (INT32U *)ptos;                /* Load stack pointer                                      */
    *--stk = (INT32U)pdata;         /* Simulate call to function with argument                 */                                    
	*--stk = (INT32U)0X00000000;	//子程序是從當前esp＋4處取得傳入的參數，所以此處要空出4個字節
	*--stk = (INT32U)task;          /* Put pointer to task   on top of stack                   */
    *--stk = (INT32U)0x00000202;				/* EFL = 0X00000202												*/
	*--stk = (INT32U)0xAAAAAAAA;                /* EAX = 0xAAAAAAAA                                              */
    *--stk = (INT32U)0xCCCCCCCC;                /* ECX = 0xCCCCCCCC                                             */
    *--stk = (INT32U)0xDDDDDDDD;                /* EDX = 0xDDDDDDDD                                             */
    *--stk = (INT32U)0xBBBBBBBB;                /* EBX = 0xBBBBBBBB                                             */
    *--stk = (INT32U)0x00000000;                /* ESP = 0x00000000  esp可以任意，因為                                           */
    *--stk = (INT32U)0x11111111;                /* EBP = 0x11111111                                             */
    *--stk = (INT32U)0x22222222;                /* ESI = 0x22222222                                             */
    *--stk = (INT32U)0x33333333;                /* EDI = 0x33333333                                             */
	
    return ((OS_STK *)stk);
}


void OSStartHighRdy(void)
{
	OSTaskSwHook();
	OSRunning = TRUE;
	_asm{
		mov ebx, [OSTCBCur]	;//OSTCBCur結構的第一個參數就是esp
		mov esp, [ebx]		;//恢復堆棧
		
		popad		;//恢復所有通用寄存器，共8個
		popfd		;//恢復標志寄存器
		ret			;//ret 指令相當于pop eip 但保護模式下不容許使用eip
		;//永遠都不返回
	}
}



void OSCtxSw(void)
{
	_asm{
		lea	 eax, nextstart	;//任務切換回來后從nextstart開始
		push eax
			pushfd				;//標志寄存器的值
		pushad				;//保存EAX -- EDI		
		mov ebx, [OSTCBCur]
			mov [ebx], esp		;//把堆棧入口的地址保存到當前TCB結構中
	}
	
	OSTaskSwHook();
	OSTCBCur = OSTCBHighRdy;	
	OSPrioCur = OSPrioHighRdy;
	
	_asm{
		mov ebx, [OSTCBCur]
		mov esp, [ebx]		;//得到OSTCBHighRdy的esp
		
		popad				;//恢復所有通用寄存器，共8個
		popfd				;//恢復標志寄存器
		ret					;//跳轉到指定任務運行
	}
nextstart:			//任務切換回來的運行地址
	return;
}


extern CONTEXT Context;
extern HANDLE mainhandle;

void OSIntCtxSw(void)
{
	OS_STK *sp;
	OSTaskSwHook();
	
	
	sp = (OS_STK *)Context.Esp;	//得到主線程當前堆棧指針
	//在堆棧中保存相應寄存器。
	*--sp = Context.Eip;	//先保存eip
	*--sp = Context.EFlags;	//保存efl
	*--sp = Context.Eax;
	*--sp = Context.Ecx;
	*--sp = Context.Edx;
	*--sp = Context.Ebx;
	*--sp = Context.Esp;	//此時保存的esp是錯誤的，但OSTCBCur保存了正確的
	*--sp = Context.Ebp;
	*--sp = Context.Esi;
	*--sp = Context.Edi;	
	OSTCBCur->OSTCBStkPtr = (OS_STK *)sp;	//保存當前esp
	
	OSTCBCur = OSTCBHighRdy;		//得到當前就緒最高優先級任務的tcb
	OSPrioCur = OSPrioHighRdy;		//得到當前就緒任務最高優先級數
	sp = OSTCBHighRdy->OSTCBStkPtr;	//得到重新執行的任務的堆棧指針
	
	
	//恢復所有處理器的寄存器
	Context.Edi = *sp++;
	Context.Esi = *sp++;
	Context.Ebp = *sp++;
	Context.Esp = *sp++;		//此時上下文中得到的esp是不正確的
	Context.Ebx = *sp++;
	Context.Edx = *sp++;
	Context.Ecx = *sp++;
	Context.Eax = *sp++;
	Context.EFlags = *sp++; 
	Context.Eip = *sp++;
	
	Context.Esp = (unsigned long)sp;		//得到正確的esp
	
	SetThreadContext(mainhandle, &Context);	//保存主線程上下文
}




void OSInitHookBegin (void)
{
}

void OSInitHookEnd (void)
{
}

void OSTaskCreateHook (OS_TCB *ptcb)
{
    ptcb = ptcb;                       /* Prevent compiler warning                                     */
}

void OSTaskDelHook (OS_TCB *ptcb)
{
    ptcb = ptcb;                       /* Prevent compiler warning                                     */
}

void OSTaskSwHook (void)
{

}

void OSTaskStatHook (void)
{

}

void OSTCBInitHook (OS_TCB *ptcb)
{
    ptcb = ptcb;                                           /* Prevent Compiler warning                 */
}

void OSTimeTickHook (void)
{

}

void OSTaskIdleHook (void)
{
	Sleep(1);
}


void CALLBACK OSTickISR(unsigned int a,unsigned int b,unsigned long c,unsigned long d,unsigned long e)
{
	if(!FlagEn)
		return;	//如果當前中斷被屏蔽則返回


	//掛起線程  --//中止主線程的運行，模擬中斷產生.但沒有保存寄存器
	SuspendThread(mainhandle);

	//得到主線程上下文，為切換任務做準備
	GetThreadContext(mainhandle, &Context);	

	OSIntNesting++;
	if (OSIntNesting == 1) 
	{
		OSTCBCur->OSTCBStkPtr = (OS_STK *)Context.Esp;	//保存當前esp
	}	
	OSTimeTick();		// ucos內部定時

	OSIntExit();		// 由于不能使用中斷返回指令，所以此函數是要返回的
	

	ResumeThread(mainhandle);	//模擬中斷返回，主線程得以繼續執行
	
}