x86汇编

高级语言的while循环如下：

while( val1 < val2 )
{
    val1++；
    val2 --；
}

用汇编语言实现这个结构时，可以很方便地改变循环条件，当条件为真时，跳转到 endwhile。

.data
val1 word 2
val2 word 9
 
.code
main proc
	nop
	begin_while:
	mov ax, val1
	cmp ax, val2
	jnl end_while
	inc word ptr val1
	dec word ptr val2
	jmp begin_while
	end_while:
	invoke ExitProcess, 0
main endp
end main

高级语言尤其善于表示嵌套的控制结构。如下 C++ 代码所示，在一个 WHILE 循环中有嵌套 IF 语句。它计算所有大于 sample 值的数组元素之和：

int array[] = {10,60,20,33,72,89,45,65,72,18};
int sample  =  50;
int ArraySize = sizeof array / sizeof sample;
int index = 0;
int sum  =  0;
while( index < ArraySize )
{
    if( array[index] > sample )
    {
        sum += array[index];
    }
    index++;
}

.data
array sdword 10,60,20,33,72,89,45,-65,-72,18
sample sdword 50
sum dword 0
 
.code
main proc
	nop
    mov eax, sum
    mov edx, sample
    mov ecx, lengthof array
    mov esi, 0
    begin_while:
        cmp esi, ecx
        jae end_while
        cmp array[esi*type array], edx
        jng L1
        add eax, array[esi*type array]
        L1: inc esi 
        jmp begin_while
    end_while:
    mov sum, eax
	invoke ExitProcess, 0
main endp
end main