深入理解计算机系统 家庭作业 2.92

去负号f

float_bits float_negate(float_bits f)
{
        unsigned exp =f >> 23 & 0xff;
        unsigned sign = f >> 31;
        if(exp == 0xff)
                return f;
        if(sign == 0x000000001)
                f = f & 0x7fffffff;
        else
                f = f | 0x8fffffff;
        return f;    
}