ZSTD Compression Backend Added

[pete4abw]

The -Z | --zstd option has been added to lrzip-next to access zstd compression. While results don't really shine, zstd is being used everywhere. So, why not here? But it is very fast. See select results below.

See The zstd_poc branch

Some notes.

• zstd compression levels are only 1-9 as enumerated here

/* Compression strategies, listed from fastest to strongest */
typedef enum { ZSTD_fast=1,
               ZSTD_dfast=2,
               ZSTD_greedy=3,
               ZSTD_lazy=4,
               ZSTD_lazy2=5,
               ZSTD_btlazy2=6,
               ZSTD_btopt=7,
               ZSTD_btultra=8,
               ZSTD_btultra2=9
               /* note : new strategies _might_ be added in the future.
                         Only the order (from fast to strong) is guaranteed */
} ZSTD_strategy;

• The basic compression and decompression functions are used

/***************************************
*  Simple API
***************************************/
/*! ZSTD_compress() :
 *  Compresses `src` content as a single zstd compressed frame into already allocated `dst`.
 *  Hint : compression runs faster if `dstCapacity` >=  `ZSTD_compressBound(srcSize)`.
 *  @return : compressed size written into `dst` (<= `dstCapacity),
 *            or an error code if it fails (which can be tested using ZSTD_isError()). */
ZSTDLIB_API size_t ZSTD_compress( void* dst, size_t dstCapacity,
                            const void* src, size_t srcSize,
                                  int compressionLevel);

/*! ZSTD_decompress() :
 *  `compressedSize` : must be the _exact_ size of some number of compressed and/or skippable frames.
 *  `dstCapacity` is an upper bound of originalSize to regenerate.
 *  If user cannot imply a maximum upper bound, it's better to use streaming mode to decompress data.
 *  @return : the number of bytes decompressed into `dst` (<= `dstCapacity`),
 *            or an errorCode if it fails (which can be tested using ZSTD_isError()). */
ZSTDLIB_API size_t ZSTD_decompress( void* dst, size_t dstCapacity,
                              const void* src, size_t compressedSize);

Some results.

$ LRZIP=NOCONFIG src/lrzip-next -L7 --zstd -O $PWD -S .L7.zstd.lrz linux-6.x.tar
linux-6.x.tar - Compression Ratio: 9.169. bpb: 0.873. Average Compression Speed: 99.900MB/s.
Total time: 00:00:20.22
$ LRZIP=NOCONFIG src/lrzip-next -L7 --lzma -O $PWD -S .L7.lzma.lrz linux-6.x.tar
linux-6.x.tar - Compression Ratio: 11.708. bpb: 0.683. Average Compression Speed: 13.779MB/s.
Total time: 00:02:25.24

228,542,125 Jan 26 12:44 linux-6.x.tar.L7.zstd.lrz
178,973,691 Jan 26 12:44 linux-6.x.tar.L7.lzma.lrz

[pete4abw]

Merged into whats-next branch

[pete4abw]

Some distros do not include the static zstd library, libzstd.a (like Slackware), or package it separately. Considering adding the library of zstd to the source tree which will permit static building of lrzip-next. Will probably release main branch anyway, but this will be a new item to tackle.

[pete4abw]

Merged into lzma-22.01 branch. However, see #112 for some fixes proposed. These are in the whats-next branch