乘法.asm

本科优秀毕业设计,倒车雷达,用单片机和c51实现的!

  ORG 0000H
  JMP MAIN

MAIN: MOV R3,#01H
      MOV R2,#05H
	  MOV R1,#01H
	  MOV R0,#05H

;************************************
;*      两字节无符号数乘法程序		*
;************************************
;R7R6R5R4<=R3R2*R1R0
;因为是两字节，所以要做16次，即：10H次
MUL2BY2: CLR	A
	     MOV	R7, A
		 MOV	R6, A
		 MOV    R5, A
		 MOV	R4, A
		 MOV	52H, #10H
MULLOOP1:CLR	C
		 MOV	A, R4
		 RLC	A
		 MOV	R4, A
		 MOV	A,	R5
		 RLC	A
		 MOV	R5, A
		 MOV	A, R6
		 RLC	A
		 MOV	R6, A
		 MOV	A, R7
		 RLC	A
		 MOV    R7, A
		 MOV    A, R0
		 RLC    A
		 MOV	R0, A
		 MOV	A, R1
		 RLC	A
		 MOV	R1, A
		 JNC	MULLOOP2
		 MOV	A, R4
		 ADD	A, R2
		 MOV	R4, A
		 MOV	A, R5
		 ADDC	A, R3
		 MOV	R5, A
		 MOV	A, R6
		 ADDC	A, #00H
		 MOV	R6, A
		 MOV	A, R7
		 ADDC	A, #00H
		 MOV	R7, A
MULLOOP2:DJNZ	52H, MULLOOP1




END