devel/base64: Add base64 0.5.2

This is an implementation of a base64 stream encoding/decoding library in C99
with SIMD (AVX2, AVX512, NEON, AArch64/NEON, SSSE3, SSE4.1, SSE4.2, AVX) and
OpenMP acceleration. It also contains wrapper functions to encode/decode simple
length-delimited strings. This library aims to be:
- FAST;
- easy to use;
- elegant.

On x86, the library does runtime feature detection. The first time it's called,
the library will determine the appropriate encoding/decoding routines for the
machine. It then remembers them for the lifetime of the program. If your
processor supports AVX2, SSSE3, SSE4.1, SSE4.2 or AVX instructions, the library
will pick an optimized codec that lets it encode/decode 12 or 24 bytes at a
time, which gives a speedup of four or more times compared to the "plain"
bytewise codec.

AVX512 support is only for encoding at present, utilizing the AVX512 VL and VBMI
instructions. Decoding part reused AVX2 implementations. For CPUs later than
Cannonlake (manufactured in 2018) supports these instructions.

NEON support is hardcoded to on or off at compile time, because portable runtime
feature detection is unavailable on ARM.

Even if your processor does not support SIMD instructions, this is a very fast
library. The fallback routine can process 32 or 64 bits of input in one round,
depending on your processor's word width, which still makes it significantly
faster than naive bytewise implementations. On some 64-bit machines, the 64-bit
routines even outperform the SSSE3 ones.

0 files changed, 0 insertions, 0 deletions