This repository contains my journey of improving the performance of decoding a block of UUEncoded (Unix-to-Unix Encoding) text to 8-bit data.
Although it shows the algorithm for decoding the 6-bit (base-64) encoded text to 8-bit binary, this is not a complete implementation of the UUEncoding scheme.
It should not be used for anything more than a reference.
I started out with various scalar ways of decoding 4-byte blocks, and then went on to try my hands on vectorization. The fastest implementations are a 256 bit Avx2 version, and an unrolled 2x128 bit Sse2/Ssse3 version.
The benchmarks are in the order of implementation, though some of them are identical.
Initially, I didn't use [MethodImpl( MethodImplOptions.AggressiveInlining )],
but I chose to do it for all the methods here.
This means Decode16Bytes_v10 and Decode16Bytes_v10_Inline are identical.
- There are no checks whether the CPU supports the instructions needed. Use with care.
Thanks to the people on Discord who's helped me.