双字节除法.doc

ORG 0000H;8051 071205MOV R7,#08H;r7r6r7MOV R6,#05H;r5r4r5MOV R5,#03HMOV R4,#03HMOV R0,#00H;r0LOOP: CLR CMOV A,R6MOV R2,A;r2SUBB A,R4MOV R6,AMOV A,R7MOV R3,A;r3SUBB A,R5MOV R7,AJC OVER;r7r6r5r4INC R0AJMP LOOPOVER: NOP;r3r2r3END& =;IN: R7R6R5R4R3R2 =;OUT: OV=0 R7R6OV=1 =;USE: PSWABR1R2 =;=UI_DIV: CLR C MOV A,R6SUBB A,R2MOV A,R7SUBB A,R3JC UI_DV1SETB OV RETUI_DV1: MOV B,#10H UI_DV2: CLR C MOV A,R4RLC AMOV R4,AMOV A,R5RLC AMOV R5,AMOV A,R6RLC AMOV R6,AXCH A,R7RLC AXCH A,R7MOV F0,C CLR CSUBB A,R2 R7R6-R3R2MOV R1,AMOV A,R7SUBB A,R3ANL C,/F0 JC UI_DV3MOV R7,A MOV A,R1MOV R6,AINC R4 UI_DV3: DJNZ B,UI_DV2;R5R4MOV A,R5 R7R6MOV R7,AMOV A,R4MOV R6,ACLR OV UIDEND: RET&;*;* / *;*;R7R6R5R4/R3R2=R7R6R5R4().R1R0();DIV4BY2: MOV 46H, #20HMOV R0, #00HMOV R1, #00HDIVLOOP1: MOV A, R4RLC AMOV R4, AMOV A, R5RLC AMOV R5, AMOV A, R6RLC AMOV R6, AMOV A, R7RLC AMOV R7, AMOV A, R0RLC AMOV R0, AMOV A, R1RLC AMOV R1, ACLR CMOV A, R0SUBB A, R2MOV B, AMOV A, R1SUBB A, R3,1988(),:(1) IBM PC ,(2),(3)(),:, 6.3.7 :,:1,2,()MCS-51DQ51.ASM,:1:R0R1R0R1:R0=123456H,(R0)=30H,(30H)=12H,(31H)=34H,(32H)=56H2:3:PSWABR2R7,(1) : BCDA:BCD:R7,R0,R1:R0,CY:PSWAR2 : 2BCDA: MOV A,R7 ;R2MOV R2,AADD A,R0 ;MOV R0,AMOV A,R2ADD A,R1MOV R1,ACLR CBCD1: DEC R0 ;DEC R1MOV A,R0ADDC A,R1 ;DA A ;MOV R0,A ;R0DJNZ R2,BCD1 ;RET(2) : BCDB:BCD:R7,R0,R1MOV A,R0 ;SWAP A ;MOV R0,A ;MOV A,R3 ;XCHD A,R0 ;MOV R3,A ;DJNZ R2,BRL1 ;RET(5) : MULD:R2R3,R6R7:R2R3R4R5:PSWABR2R7 : 2MULD: MOV A,R3 ;R3R7MOV B,R7MUL ABMOV R4,B ;MOV R5,AMOV A,R3 ;R3R6MOV B,R6MUL ABADD A,R4 ;MOV R4,ACLR AADDC A,BMOV R3,AMOV A,R2 ;R2R7MOV B,R7MUL ABADD A,R4 ;MOV R4,AMOV A,R3ADDC A,BMOV R3,ACLR ARLC AXCH A,R2 ;R2R6MOV B,R6MUL ABADD A,R3 ;MOV R3,AMOV A,R2ADDC A,BMOV R2,ARET(6) : MUL2:R2R3:R2R3R4R5:PSWABR2R5 : 2MOV R3,AXCH A,R2RLC AXCH A,R2MOV F0,C ;CLR CSUBB A,R7 ;(R2R3-R6R7)MOV R1,AMOV A,R2SUBB A,R6ANL C,/F0 ;JC DVD3MOV R2,A ;,MOV A,R1MOV R3,AINC R5 ;DVD3: DJNZ B,DVD2 ;(R4R5)MOV A,R4 ;R2R3MOV R2,AMOV A,R5MOV R3,ACLR OV ;RET(8) : D457:R4R5,R7:OV=0 ,R3,OV=1 :PSWAR3R7 : 2D457: CLR CMOV A,R4SUBB A,R7JC DV50SETB OV ;RETDV50: MOV R6,#8 ;(R4R5/R7-R3)DV51: MOV