Generating 32-bit random number seed on 16-bit CPU

Question

I'm writing a program in assembly for a 16-bit CPU (8086), and I need to generate a 32-bit random number seed. I have about 80 bits of entropy, but many of those bits are not completely uniformly random. How do I combine those 80 bits to a random number seed of 32 bits, so that each bit of the seed (and the entire seed itself) would be much more uniformly distributed random than each of the original 80 bits?

Preferably I need a short and simple algorithm, C code or 8086 assembly code.

I need something better than just xor the entropy bits together, preferably something which was proven to be high quality by randomness probes and/or mathematical theory.

I need something shorter than just compute the MD5 and take the first 32 bits, because the MD5 algorithm implementation is quote long.

I'm aware of MurmurHash3 32-bit (see C implementation), but it's too long, and it uses too many 32-bit operations (e.g. multiplication). I need something shorter and simpler for a 16-bit CPU.