uC/OS-II在51单片机上的移植1

tCtxSw()过程中压入堆栈的多余内容
SP=SP-4

MOV A,SP
CLR C
SUBB A,#4
MOV SP,A

LJMP OSIntCtxSw_in
-------------------------------------------------------------------------
CSEG AT 000BH ;OSTickISR
LJMP OSTickISR ;使用定时器0
RSEG ?PR?OSTickISR?OS_CPU_A

OSTickISR:

USING 0
PUSHALL

CLR TR0
MOV TH0,#70H ;定义Tick=50次/秒(即0.02秒/次)
MOV TL0,#00H ;OS_CPU_C.C 和 OS_TICKS_PER_SEC
SETB TR0

LCALL _?OSIntEnter
LCALL _?OSTimeTick
LCALL _?OSIntExit
POPALL
RETI
-------------------------------------------------------------------------
CSEG AT 0023H ;串口中断
LJMP SerialISR ;工作于系统态，无任务切换。
RSEG ?PR?_?serial?OS_CPU_A

SerialISR:

USING 0
PUSHALL
CLR EA
LCALL _?serial
SETB EA
POPALL
RETI
-------------------------------------------------------------------------
END
-------------------------------------------------------------------------

文件名 : OS_CPU_C.C

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

ppdata = ppdata;
opt = opt; //opt没被用到，保留此语句防止告警产生
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
*stk++ = 0x01; //R1
*stk++ = 0x02; //R2
*stk++ = 0x03; //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。
return ((void *)ptos);
}

#if OS_CPU_HOOKS_EN
void OSTaskCreateHook (OS_TCB *ptcb) reentrant
{
ptcb = ptcb;
}

void OSTaskDelHook (OS_TCB *ptcb) reentrant
{
ptcb = ptcb;
}

void OSTimeTickHook (void) reentrant
{
}
#endif

//初始化定时器0
void InitTimer0(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(即0.02秒/次)
TL0=0x00; //OS_CPU_A.ASM 和 OS_TICKS_PER_SEC
ET0=1; //允许T0中断
TR0=1;
}