SDOMUL: MOV 24H,R1 MOV A,R1 ADD A,R2 DEC A MOV R1,A MOV A,@R1 ANL A,#80H MOV R6,A JZ NEG0 NEG1: MOV R1,24H MOV 22H,R2 ACALL NEGTUN NEG0: MOV 28H,R0 MOV A,R0 ADD A,R3 DEC A MOV R0,A MOV A,@R0 ANL A,#80H MOV R7,A JZ DDOMUL MOV R1,#28H MOV 22H,R3 ACALL NEGTUN DDOMUL: MOV A,R6 XRL A,R7 MOV 23H,A MOV R0,28H MOV R1,24H ACALL DOMUL JNB 1FH,RETURN NEG2: MOV R1,27H MOV 22H,R5 ACALL NEGTUN RETURN: RET NEGTUN: SETB C LP: MOV A,@R1 CPL A ADDC A,#00H MOV @R1,A INC R1 DJNZ 22H,LP RET