8位单片机乘法函数

;NAME:F_Mul
;INPUT:R_opA,R_opB
;OUTPUT:R_opRes,R_opMod
;FUN:R_opMod积高位(当积大于255)，R_opRes积低位
;--------------------------------------------
.IFJ_MulOpera
F_Mul:
LDAR_opB
PHA

LDA#00H
STAR_opMod
STAR_opRes

LDAR_opA
ORAR_opB
BEQEND_MUL

MUL_LOOP:
%ClearWDT

LDAR_opB
BEQEND_MUL

CLC
LDAR_opRes
ADCR_opA
STAR_opRes

LDA#00H
ADCR_opMod
STAR_opMod

DECR_opB
JMPMUL_LOOP

END_MUL:
PLA
STAR_opB
LDAR_opRes
RTS
.ENDIF