[求助]汇编的乘法、除法怎么实现

麻烦大家看看这个C程序怎么用汇编程序实现，小弟万分感激
double tanh(double x)
{
float a;
float b;
float c;
double y;
if (x > 20)
return 1;
else if (x < -20)
return -1;
else
{
a = expf(x);
b = expf(-x);
c=(a-b)/(a+b);
y=(double)c;
return y;
}
}