    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 data sharing and long-term archiving,
    taking into account both data integrity and decoder availability:

       * The lzip format provides very safe integrity checking and some data
         recovery means. The program lziprecover can repair bit flip errors
         (one of the most common forms of data corruption) in lzip files, and
         provides data recovery capabilities, including error-checked merging
         of damaged copies of a file.

       * The lzip format is as simple as possible (but not simpler). The lzip
         manual provides the source code of a simple decompressor along with a
         detailed explanation of how it works, so that with the only help of the
         lzip manual it would be possible for a digital archaeologist to extract
         the data from a lzip file long after quantum computers eventually
         render LZMA obsolete.

       * Additionally the lzip reference implementation is copylefted, which
         guarantees that it will remain free forever.

    A nice feature of the lzip format is that a corrupt byte is easier to repair
    the nearer it is from the beginning of the file. Therefore, with the help of
    lziprecover, losing an entire archive just because of a corrupt byte near
    the beginning is a thing of the past.

    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 'bbexample.c', 'ffexample.c', and 'main.c' from the source
    distribution.

    Compression/decompression is done by repeatedly calling a couple of
    read/write functions until all the data have 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
    a read call, even if a lot of data are written. If you want the data to be
    compressed in advance, just call the read function with a size equal to 0.

    If all the data to be compressed are written in advance, lzlib will
    automatically adjust the header of the compressed data to use the largest
    dictionary size that does not exceed neither the data size nor the limit
    given to 'LZ_compress_open'. This feature reduces the amount of memory
    needed for decompression and allows minilzip to produce identical compressed
    output as lzip.

    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.

    Lzlib is able to compress and decompress streams of unlimited size by
    automatically creating multimember output. The members so created are large,
    about 2 PiB each.

    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.

    In spite of its name (Lempel-Ziv-Markov chain-Algorithm), LZMA is not a
    concrete algorithm; it is more like "any algorithm using the LZMA coding
    scheme". For example, the option '-0' of lzip uses the scheme in almost the
    simplest way possible; issuing the longest match it can find, or a literal
    byte if it can't find a match. Inversely, a much more elaborated way of
    finding coding sequences of minimum size than the one currently used by lzip
    could be developed, and the resulting sequence could also be coded using the
    LZMA coding scheme.

    Lzlib currently implements two variants of the LZMA algorithm; fast (used by
    option '-0' of minilzip) and normal (used by all other compression levels).

    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).

    LANGUAGE NOTE: Uncompressed = not compressed = plain data; it may never have
    been compressed. Decompressed is used to refer to data which have undergone
    the process of decompression.

    Copyright (C) 2009-2021 Antonio Diaz Diaz.

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

    The file Makefile.in is a data file used by configure to produce the
    Makefile. It has the same copyright owner and permissions that configure
    itself.