Base64 decoding with SIMD instructions

Introduction Surprisingly good results of base64 encoding with SIMD instructions forced me to check the opposite algorithm, i.e. the decoding. The decoding is slightly more complicated as it has to check the input's validity. A decoder must also consider character '=' at the end of input, but since it's done once, I didn't bother with this in a sample code. 2016-12-18 note: in the initial version

[kazuhooku]

あとで