移位指令实现乘法

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include irvine32.inc; .data i dword 0; sum qword 0; str1 byte “请输入16进制的(32位整数)乘数和被乘数”,0 str2 byte “乘积为：”,0; j dword 0;

.code

main proc

L1: mov edx,offset str1; call writestring;

mov j,0; mov eax,0;eax为（低32位）乘积值； mov ebx,0;edx为（低32位）乘积值的中间值 mov edx,0; mov esi,0;dsi为（高32位）乘积值的中间值 mov edi,0;edi为（高32位）乘积值； mov cl,0;cl为移位的位数

call readhex; cmp eax,80000000h;

jna L4; neg eax; inc j; L4: mov ebx,eax; ebx存储乘数（来移位的） ;call writeint;

call readhex; cmp eax,80000000h;

jna L5; neg eax; inc j; L5: mov i,eax; ;call writeint; mov eax,0; cmp ebx, 0; jne L2; cmp i,0; je finally;

L2: cmp ebx,0; jz quit; shr ebx,1; jnc next;if(ZF==0)

mov esi,0;每次都要清零； mov edx,i;

shld esi,edx,cl; shl edx,cl;

add eax,edx; jnc L3;if(ZF==0) add edi,1;

L3: add edi,esi; next: inc cl; jmp L2;

quit: call crlf; mov edx,offset str2; call writestring; mov ebx,eax;

cmp j,1; jne L6; add edi,80000000h ;call writestring L6:

mov eax,edi; call writehex;

mov eax,ebx; call writehex;

call crlf;

jmp L1;

finally:

exit main endp; end main

转载于:https://www.cnblogs.com/hqu-ye/archive/2013/02/25/2932588.html

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