8086汇编求最小公约数（输入范围：-32768~32767，有提示信息）

Posted 2021-12-07 u25th_engineer

图 1 运行示意（正数、负数）

图 2 运行示意（四位整数）

图 3 运行示意（五位整数）

图 4 运行示意（正数、负数）

stack	segment stack
        db 512 dup(?)
stack	ends

data    segment
        string1 db 'Enter the first number M:', 0ah, 0dh, '$'
		string2 db 'Enter the second number N:', 0ah, 0dh, '$'
		string3 db 'The greatest common divisor(GCD) of M and N is:', 0ah, 0dh, '$'
data    ends

code 	segment
        assume ds: data, cs: code, ss: stack

start:
		mov 	ax, stack
		mov 	ss, ax
		mov		ax, data
		mov		ds, ax
		
		lea 	dx, string1
		mov 	bh, ah
		mov 	ah, 09h
		int 	21h
		mov 	ah, bh
		
		push	ax
		call	far ptr readsiw
		
		lea 	dx, string2
		mov 	bh, ah
		mov 	ah, 09h
		int 	21h
		mov 	ah, bh
		
		push	ax
		call	far ptr readsiw
		push	ax
		call	far ptr gcd
		
		lea 	dx, string3
		mov 	bh, ah
		mov 	ah, 09h
		int 	21h
		mov 	ah, bh
		
		call	far ptr dispsiw
		call	far ptr lineFeed
		jmp		done

readsiw proc far
		push bx
		push cx
		push dx
		xor bx, bx   
		xor cx, cx   
		mov ah, 1
		int 21h
		cmp al, '+'
		jz rsiw1
		cmp al, '-'
		jnz rsiw2
		mov cx, -1
rsiw1: 
		mov ah,  1
		int 21h
rsiw2:    
		cmp al, '0'
		jb rsiw3
		cmp al, '9'
		ja rsiw3
		sub al, 30h
		xor ah, ah
		shl bx, 1
		mov dx, bx
		shl bx, 1
		shl bx, 1
		add bx, dx
		add bx, ax
		jmp rsiw1
rsiw3:
		cmp cx, 0
		jz rsiw4
		neg bx
rsiw4:
		mov ax, bx
		pop dx
		pop cx
		pop bx
		ret
readsiw endp

dispsiw proc far
		push ax
		push bx
		push dx
		test ax, ax 
		jnz dsiw1
		mov dl, '0' 
		mov ah, 2
		int 21h
		jmp dsiw5
dsiw1:
		jns dsiw2  
		mov bx, ax
		mov dl, '-'
		mov ah, 2
		int 21h
		mov ax, bx
		neg ax 
dsiw2:  
		mov bx, 10
		push bx 
dsiw3:
		cmp ax, 0
		jz dsiw4
		xor dx, dx 
		div bx  
		add dl, 30h  
		push dx     
		jmp dsiw3
dsiw4:
		pop dx
		cmp dl, 10
		je dsiw5
		mov ah, 2
		int 21h
		jmp dsiw4
dsiw5:
		pop dx
		pop bx
		pop ax
		ret
dispsiw endp

lineFeed proc far
		push ax
		push dx
		mov dl, 0dh
		mov ah, 2
		int 21h
		mov dl, 0ah
		mov ah, 2
		int 21h
		pop dx
		pop ax
		ret
lineFeed endp

gcd		proc	far
		push	bp
		mov	bp,sp
		push	si
		push	di
		mov	si,word ptr [bp+6]
		mov	di,word ptr [bp+8]
		jmp	short gcd_judge
gcd_judge:
		mov	ax,si
		cwd	
		idiv	di
		mov	si,dx
		mov	ax,dx
		xor	di,ax
		mov	ax,di
		xor	si,ax
		mov	ax,si
		xor	di,ax
		jne	short gcd_judge
	  
		mov	ax,si
		jmp	short gcd_done
gcd_done:
		pop	di
		pop	si
		pop	bp
		ret	
gcd		endp

done:
		mov 	ax, 4c00h
		int 	21h	
	
code	ends

		end start