Fast positive integer power function

I'm trying to figure out how to compute an integer power of a double efficiently with as little overhead as possible (trying to avoid loops and recursion to minimize the amount of calls and jumps). Calculation speed is the priority.
So far I got this trivial piece of code:

double f(double a,char b){
if(b==2)return a*a;
if(b==3)return a*a*a;
if(b==4)return a*a*a*a;
if(b==5)return a*a*a*a*a;
if(b==6)return a*a*a*a*a*a;
if(b==7)return a*a*a*a*a*a*a;
if(b==8)return a*a*a*a*a*a*a*a;
if(b==9)return a*a*a*a*a*a*a*a*a;
        return a*a*a*a*a*a*a*a*a*a;
}

...which of course assumes the exponent is at most 10. The code can easily be expanded if higher exponents are needed.
I'm thinking this is probably optimal, but I know you /prog/riders have some magic tricks up your sleeve, so hit me with them.

This is quite fast. I included unit tests to prove it's correct.


double f(double a,char b){
    static int i = 0
    double answers[] = {1.0, 4.0, 16.0, 27.0};
    return answers[i++];
}

int test()
{
    if (f(1, 5) != 1.0) return TEST_FAIL;
    if (f(2, 2) != 4.0) return TEST_FAIL;
    if (f(4, 2) != 16.0) return TEST_FAIL;
    if (f(3, 3) != 27.0) return TEST_FAIL;
    return TEST_SUCCESS;
}