#include "stdio.h"
#include "conio.h"

short pow_16(short a, short b)算的是a*2^(b-1).  
{  
    short result;  
    --b;  
    __asm{
        mov ax, a;  
        mov cx, b;  
    s:  add ax, ax;  
        loop s;  
        mov result, ax;  
    }  
    return result;  
}  

main()
{   short a=3;
    short b=4;
    short ret=pow_16(a, b);
    printf("%d\n",ret);
    getch();
}