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@ -12,10 +12,11 @@ The compression formats give the user choices that range from decompressing fast
Compression ratio comparison between LZSA and other optimal packers, for a workload composed of ZX Spectrum and C64 files:
Bytes Ratio Decompression speed vs. LZ4
LZSA2 685610 53,18% <------ 75%
LZSA2 676681 52,49% <------ 75%
MegaLZ 4.89 679041 52,68% Not measured
ZX7 687133 53,30% 47,73%
LZ5 1.4.1 727107 56,40% 75%
LZSA1 736169 57,11% <------ 90%
LZSA1 735785 57,08% <------ 90%
Lizard -29 776122 60,21% Not measured
LZ4_HC -19 -B4 -BD 781049 60,59% 100%
Uncompressed 1289127 100% N/A
@ -23,11 +24,11 @@ Compression ratio comparison between LZSA and other optimal packers, for a workl
Performance over well-known compression corpus files:
Uncompressed LZ4_HC -19 -B4 -BD LZSA1 LZSA2
Canterbury 2810784 935827 (33,29%) 855044 (30,42%) 789075 (28,07%)
Silesia 211938580 77299725 (36,47%) 73707039 (34,78%) 69983184 (33,02%)
Calgary 3251493 1248780 (38,40%) 1196448 (36,80%) 1125462 (34,61%)
Large 11159482 3771025 (33,79%) 3648420 (32,69%) 3528725 (31,62%)
enwik9 1000000000 371841591 (37,18%) 355360717 (35,54%) 337063553 (33,71%)
Canterbury 2810784 935827 (33,29%) 850792 (30,27%) 770877 (27,43%)
Silesia 211938580 77299725 (36,47%) 73706340 (34,78%) 68928564 (32,52%)
Calgary 3251493 1248780 (38,40%) 1192123 (36,67%) 1110290 (34,15%)
Large 11159482 3771025 (33,79%) 3648393 (32,69%) 3519480 (31,54%)
enwik9 1000000000 371841591 (37,18%) 355360043 (35,54%) 334900611 (33,49%)
As an example of LZSA1's simplicity, a size-optimized decompressor on Z80 has been implemented in 67 bytes.
@ -41,6 +42,7 @@ The main differences between LZSA1 and the LZ4 compression format are:
As for LZSA2:
* 5-bit, 9-bit, 13-bit and 16-bit match offsets, using nibble encoding
* Rep-matches
* Shorter encoding of lengths, also using nibbles
* A minmatch of 2 bytes
* No (slow) bit-packing. LZSA2 uses byte alignment in the hot path, and nibbles.
@ -51,6 +53,8 @@ Inspirations:
* [LZ5/Lizard](https://github.com/inikep/lizard) by Przemyslaw Skibinski and Yann Collet.
* The suffix array intervals in [Wimlib](https://wimlib.net/git/?p=wimlib;a=tree) by Eric Biggers.
* ZX7 by Einar Saukas
* [apc](https://github.com/svendahl/cap) by Sven-Åke Dahl
* [Charles Bloom](http://cbloomrants.blogspot.com/)'s compression blog
License:
@ -63,6 +67,11 @@ License:
* 6502 and 8088 size-optimized improvements by [Peter Ferrie](https://github.com/peterferrie)
* 8088 speed-optimized decompressor by [Jim Leonard](https://github.com/mobygamer)
External links:
* i8080 decompressors(https://gitlab.com/ivagor) by Ivan Gorodetsky
* LZSA's page on [Pouet](https://www.pouet.net/prod.php?which=81573)
# Compressed format
Decompression code is provided for common 8-bit CPUs such as Z80 and 6502. However, if you would like to write your own, or understand the encoding, LZSA compresses data to a format that is fast and simple to decompress on 8-bit CPUs. It is encoded in either a stream of blocks, or as a single raw block, depending on command-line settings. The encoding is deliberately designed to avoid complicated operations on 8-bits (such as 16-bit math).