Speedup a short to float cast?

Question

I have a short to float cast in C++ that is bottlenecking my code.

The code translates from a hardware device buffer which is natively shorts, this represents the in

Answer 1

You could try to approximate the expression

float factor = 1.0f/value;

by an fraction numerator/denomitator where both numerator and denominator are ints. This can be done to the precision you need in your application like

int denominator = 10000;
int numerator = factor * denominator;

Then you can do your computation in integer arithmetics like

int value = source[i];
destination[i] = (value * numerator) / numerator;

You have to take care of overflows, perhaps you need to switch to long (or even long long on 64bit systems) for the calculation.