I need a cross-platform library/algorithm that will convert between 32-bit and 16-bit floating point numbers. I don't need to perform math with the 16-bit numbers; I just need to decrease the size of the 32-bit floats so they can be sent over the network. I am working in C++.
I understand how much precision I would be losing, but that's OK for my application.
The IEEE 16-bit format would be great.
std::frexp extracts the significand and exponent from normal floats or doubles -- then you need to decide what to do with exponents that are too large to fit in a half-precision float (saturate...?), adjust accordingly, and put the half-precision number together. This article has C source code to show you how to perform the conversion.