Description

Lzlib is a data compression library providing in-memory LZMA compression
and decompression functions, including integrity checking of the
decompressed data. The compressed data format used by the library is the
lzip format. Lzlib is written in C.

The lzip file format is designed for long-term data archiving. It is
clean, provides very safe 4 factor integrity checking, and is backed by
the recovery capabilities of lziprecover.

The functions and variables forming the interface of the compression
library are declared in the file lzlib.h. Usage examples of the library
are given in the files main.c and bbexample.c from the source
distribution.

Compression/decompression is done by repeatedly calling a couple of
read/write functions until all the data has been processed by the
library. This interface is safer and less error prone than the
traditional zlib interface.

Compression/decompression is done when the read function is called. This
means the value returned by the position functions will not be updated
until some data is read, even if you write a lot of data. If you want
the data to be compressed in advance, just call the read function with a
size equal to 0.

Lzlib will correctly decompress a data stream which is the concatenation
of two or more compressed data streams. The result is the concatenation
of the corresponding decompressed data streams. Integrity testing of
concatenated compressed data streams is also supported.

All the library functions are thread safe. The library does not install
any signal handler. The decoder checks the consistency of the compressed
data, so the library should never crash even in case of corrupted input.

Lzlib implements a simplified version of the LZMA (Lempel-Ziv-Markov
chain-Algorithm) algorithm. The high compression of LZMA comes from
combining two basic, well-proven compression ideas: sliding dictionaries
(LZ77/78) and markov models (the thing used by every compression
algorithm that uses a range encoder or similar order-0 entropy coder as
its last stage) with segregation of contexts according to what the bits
are used for.

The ideas embodied in lzlib are due to (at least) the following people:
Abraham Lempel and Jacob Ziv (for the LZ algorithm), Andrey Markov (for
the definition of Markov chains), G.N.N. Martin (for the definition of
range encoding), Igor Pavlov (for putting all the above together in
LZMA), and Julian Seward (for bzip2's CLI).


Copyright (C) 2009, 2010, 2011, 2012, 2013 Antonio Diaz Diaz.

This file is free documentation: you have unlimited permission to copy,
distribute and modify it.

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