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#define uCOS 0x80 /* Interrupt vector # used for context switch */
#define OS_TASK_SW() asm INT uCOS
_OSCtxSw PROC FAR
;
PUSHA ; Save current task's context
PUSH ES ;
PUSH DS ;
;
MOV AX, SEG _OSTCBCur ; Reload DS in case it was altered
MOV DS, AX ;
;
LES BX, DWORD PTR DS:_OSTCBCur ; OSTCBCur->OSTCBStkPtr = SS:SP
MOV ES:[BX+2], SS ;
MOV ES:[BX+0], SP ;
;
CALL FAR PTR _OSTaskSwHook ; Call user defined task switch hook
;
MOV AX, WORD PTR DS:_OSTCBHighRdy+2 ; OSTCBCur = OSTCBHighRdy
MOV DX, WORD PTR DS:_OSTCBHighRdy ;
MOV WORD PTR DS:_OSTCBCur+2, AX ;
MOV WORD PTR DS:_OSTCBCur, DX ;
;
MOV AL, BYTE PTR DS:_OSPrioHighRdy ; OSPrioCur = OSPrioHighRdy
MOV BYTE PTR DS:_OSPrioCur, AL ;
;
LES BX, DWORD PTR DS:_OSTCBHighRdy ; SS:SP = OSTCBHighRdy->OSTCBStkPtr
MOV SS, ES:[BX+2] ;
MOV SP, ES:[BX] ;
;
POP DS ; Load new task's context
POP ES ;
POPA ;
;
IRET ; Return to new task
;
_OSCtxSw ENDP
PAGE ; /*$PAGE*/
PC_VectSet(uCOS, OSCtxSw); /* Install uC/OS-II's context switch vector */
void PC_VectSet (INT8U vect, void (*isr)(void))
{
#if OS_CRITICAL_METHOD == 3 /* Allocate storage for CPU status register */
OS_CPU_SR cpu_sr;
#endif
INT16U *pvect;
pvect = (INT16U *)MK_FP(0x0000, vect * 4); /* Point into IVT at desired vector location */
OS_ENTER_CRITICAL();
*pvect++ = (INT16U)FP_OFF(isr); /* Store ISR offset */
*pvect = (INT16U)FP_SEG(isr); /* Store ISR segment */
OS_EXIT_CRITICAL();
}