Where can I find a C# implementation of SHA-1 not using the built in libraries?

I am trying to rewrite the SHA-1 algorithm for parallelization in a personal project of mine. Just wondering if anyone knows where I can find a C# implementation of the actual mat开发者_Python百科hematical operations to perform the hash, not just the System.Security.Cryptography function.

FIPS PUB 180. I'm not going to comment whether rolling your own implementation of any crypto algorithm is a good idea...