简单的乘法器
利用汇编语言写一个乘法器
.386 assume cs:code,ds:data,ss:stack data segment use16 dec_mul dw 10 num1 db 6 db ? db 6 dup(?) num2 db 6 db ? db 6 dup(?) data ends stack segment stack db 100h dup (?) stack ends code segment use16 main: mov ax,data mov ds,ax mov dx,offset num1 mov ah,0Ah int 21h ;读入第一个数据 mov dl,0Dh mov ah,2 int 21h mov dl,0Ah mov ah,2 int 21h ;移动光标至下一行行首 mov dx,offset num2 mov ah,0Ah int 21h ;读入第二个数据 mov dl,0Dh mov ah,2 int 21h mov dl,0Ah mov ah,2 int 21h ;移动光标至下一行行首 xor cx,cx mov cl,num1[1] jcxz done mov bx,offset num1+2 jmp again1 done: mov ah,4Ch int 21h again1: mov dl,[bx] mov ah,2 int 21h mov dh,30h sub dl,dh mov [bx],dl inc bx loop again1 ;显示第一个乘数 mov dl,'*' mov ah,02h int 21h ;显示乘号 xor cx,cx mov cl,num2[1] jcxz done mov bx,offset num2+2 again2: mov dl,[bx] mov ah,2 int 21h mov dh,30h sub dl,dh mov [bx],dl inc bx loop again2 ;显示第二个乘数 mov dl,'=' mov ah,02h int 21h ;显示等于号 mov dl,0Dh mov ah,2 int 21h mov dl,0Ah mov ah,2 int 21h ;移动光标至下一行行首 xor cx,cx mov cl,num1[1] mov bx,offset num1+2 xor dx,dx xor ax,ax mov al,[bx] dec cx inc bx jcxz out_1 again_1: mul dec_mul add al,[bx] inc bx loop again_1 out_1: push ax xor cx,cx mov cl,num2[1] mov bx,offset num2+2 xor dx,dx xor ax,ax mov al,[bx] dec cx inc bx jcxz out_2 again_2: mul dec_mul add al,[bx] inc bx loop again_2 out_2: mov bx,ax pop ax mov dx,0 mul bx ;dx:ax存放乘积的高、低16位 push ax push dx push ax mov ax,dx mov cl,16 shl eax,cl pop ax ;eax存放乘积 mov cl,0 dec_: xor edx,edx mov ebx,10 div ebx push edx inc cl cmp eax,0 jne dec_ dec_show: pop edx add dl,30h mov ah,02h int 21h loop dec_show mov dl,0Dh mov ah,2 int 21h mov dl,0Ah mov ah,2 int 21h ;移动光标至下一行行首 pop dx pop ax ;dx:ax存放乘积的高、低16位 push ax push dx push ax mov ax,dx ;mov ax,6 ;显示十六进制 mov cl,0 hex_dx: mov dx,ax mov bx,ax and bx,0fff0h sub dx,bx push dx inc cl push cx xor cx,cx mov cl,4 shr ax,cl pop cx test ax,ax jnz hex_dx hex_no_show_dx: cmp cx,0 je hex_out_dx dec cl pop dx mov dh,0 cmp dl,dh je hex_no_show_dx inc cl mov dh,0 cmp cl,dh je hex_out_dx xor ax,ax mov ah,02h jmp hex_compare_dx hex_show_dx: pop dx hex_compare_dx: mov dh,9 cmp dl,dh ja hex_show_char_dx hex_show_num_dx: add dl,30h int 21h loop hex_show_dx jmp hex_out_no_dx hex_show_char_dx: add dl,55 int 21h loop hex_show_dx hex_out_no_dx: jmp hex_ax_has_zero hex_out_dx: pop ax mov cl,0 hex_ax: mov dx,ax mov bx,ax and bx,0fff0h sub dx,bx push dx push cx xor cx,cx mov cl,4 shr ax,cl pop cx inc cl test ax,ax jnz hex_ax xor ax,ax mov ah,02h hex_show_ax: pop dx mov dh,9 cmp dl,dh ja hex_show_char_ax hex_show_num_ax: add dl,30h int 21h loop hex_show_ax jmp hex_out_ax hex_show_char_ax: add dl,55 int 21h loop hex_show_ax hex_out_ax: mov dl,'h' mov ah,2 int 21h jmp hex_out_zero hex_ax_has_zero: pop ax mov cl,0 hex_ax_zero: mov dx,ax mov bx,ax and bx,0fff0h sub dx,bx push dx push cx xor cx,cx mov cl,4 shr ax,cl pop cx inc cl test ax,ax jnz hex_ax_zero push cx mov dx,4 sub dx,cx mov cx,dx cmp cx,0 je hex_no_zero hex_show_zero: mov dl,'0' mov ah,02h int 21h loop hex_show_zero hex_no_zero: pop cx xor ax,ax mov ah,02h hex_show_ax_zero: pop dx mov dh,9 cmp dl,dh ja hex_show_char_ax_zero hex_show_num_ax_zero: add dl,30h int 21h loop hex_show_ax_zero jmp hex_out_ax hex_show_char_ax_zero: add dl,55 int 21h loop hex_show_ax_zero hex_out_ax_zero: mov dl,'h' mov ah,2 int 21h hex_out_zero: mov dl,0Dh mov ah,2 int 21h mov dl,0Ah mov ah,2 int 21h ;移动光标至下一行行首 pop dx ;pop ax ;dx:ax存放乘积的高、低16位 ;目前ax还在栈中 mov ax,dx mov cl,16 bin_show_dx: mov dx,ax mov bx,ax and bx,07fffh sub dx,bx push ax xor ax,ax mov ah,02h push cx mov cx,15 shr dx,cl add dl,30h int 21h pop cx cmp cx,16 je bin_dx mov ax,cx mov dl,4 div dl cmp ah,1 jnz bin_dx mov dl,' ' mov ah,02h int 21h bin_dx: pop ax shl ax,1 loop bin_show_dx pop ax mov cl,16 bin_show_ax: mov dx,ax mov bx,ax and bx,07fffh sub dx,bx push ax xor ax,ax mov ah,02h push cx mov cx,15 shr dx,cl pop cx add dl,30h int 21h mov ax,cx mov dl,4 div dl cmp ah,1 jnz bin_ax cmp al,0 jz bin_ax mov ah,02h mov dl,' ' int 21h bin_ax: pop ax shl ax,1 loop bin_show_ax mov dl,'B' mov ah,02h int 21h mov ah,4Ch int 21h code ends end main 结果如下：