DSUB: MOV A,R6 CPL ACC.7 MOV R6,A DADD: MOV A,R3 MOV C,ACC.7 MOV SR0,C XRL A,R6 MOV C,ACC.7 MOV A,R3 CLR ACC.7 MOV R3,A MOV A,R6 CLR ACC.7 MOV R6,A JC DAB2 NADD: MOV A,R4 ADD A,R7 MOV R4,A MOV A,R3 ADDC A,R6 MOV R3,A MOV A,R3 JB ACC.7,DABE DAB1: MOV C,SR0 MOV ACC.7,C MOV R3,A CLR OV RET DABE: SETB OV RET DAB2: LCALL NSUB MOV A,R3 JNB ACC.7,DAB1 LCALL CMPT CPL SR0 SJMP DAB1 RET