?? 2.2.4多字節有符號數減法.txt
字號:
MBFSUB:
SETB F0
AS:
LCALL MVR1
MOV C,F0
RRC A
XRL A,@R1
MOV C,ACC.7
ASN:
MOV 1EH,C
XRL A,@R0
RLC A
MOV F0,C
LCALL MVR0
LCALL AS1
MOV0:
INC R0
INC R0
MOV A,R4
MOV @R0,A
DEC R0
MOV A,R3
MOV @R0,A
DEC R0
MOV A,R2
MOV C,1FH
MOV ACC.7,C
MOV @R0,A
CLR ACC.7
CLR OV
CJNE A,#3FH,MV01
SETB OV
MV01:
MOV A,@R0
RET
MVR0:
MOV A,@R0
MOV C,ACC.7
MOV 1FH,C
MOV C,ACC.6
MOV ACC.7,C
MOV R2,A
INC R0
MOV A,@R0
MOV R3,A
INC R0
MOV A,@R0
MOV R4,A
DEC R0
DEC R0
RET
MVR1:
MOV A,@R1
MOV C,ACC.7
MOV 1EH,C
MOV C,ACC.6
MOV ACC.7,C
MOV R5,A
INC R1
MOV A,@R1
MOV R6,A
INC R1
MOV A,@R1
MOV R7,A
DEC R1
DEC R1
RET
AS1:
MOV A,R6
ORL A,R7
JZ AS2
MOV A,R3
ORL A,R4
JNZ EQ1
MOV A,R6
MOV R3,A
MOV A,R7
MOV R4,A
MOV A,R5
MOV R2,A
MOV C,1EH
MOV 1FH,C
AS2:
RET
EQ1:
MOV A,R2
XRL A,R5
JZ AS4
JB ACC.7,EQ3
MOV A,R2
CLR C
SUBB A,R5
JC EQ4
EQ2:
CLR C
MOV A,R6
RRC A
MOV R6,A
MOV A,R7
RRC A
MOV R7,A
INC R5
ORL A,R6
JNZ EQ1
MOV A,R2
MOV R5,A
SJMP AS4
EQ3:
MOV A,R2
JNB ACC.7,EQ2
EQ4:
CLR C
LCALL RR1
ORL A,R3
JNZ EQ1
MOV A,R5
MOV R2,A
AS4:
JB F0,AS5
MOV A,R4
ADD A,R7
MOV R4,A
MOV A,R3
ADDC A,R6
MOV R3,A
JNC AS2
LJMP RR1
AS5:
CLR C
MOV A,R4
SUBB A,R7
MOV B,A
MOV A,R3
SUBB A,R6
JC AS6
MOV R4,B
MOV R3,A
LJMP RLN
AS6:
CPL 1FH
CLR C
MOV A,R7
SUBB A,R4
MOV R4,A
MOV A,R6
SUBB A,R3
MOV R3,A
RLN:
MOV A,R3
ORL A,R4
JNZ RLN1
MOV R2,#0C1H
RET
RLN1:
MOV A,R3
JB ACC.7,RLN2
CLR C
LCALL RL1
SJMP RLN
RLN2:
CLR OV
RET
RL1:
MOV A,R4
RLC A
MOV R4,A
MOV A,R3
RLC A
MOV R3,A
DEC R2
CJNE R2,#0C0H,RL1E
CLR A
MOV R3,A
MOV R4,A
MOV R2,#0C1H
RL1E:
CLR OV
RET
RR1:
MOV A,R3
RRC A
MOV R3,A
MOV A,R4
RRC A
MOV R4,A
INC R2
CLR OV
CJNE R2,#40H,RR1E
MOV R2,#3FH
SETB OV
RR1E:
RET
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