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Merging upstream version 1.7~rc1.

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Signed-off-by: Daniel Baumann <daniel@debian.org>
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Daniel Baumann 2025-02-17 20:40:18 +01:00
parent d13efc182f
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Signed by: daniel
GPG key ID: FBB4F0E80A80222F
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43
doc/clzip.texi
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@ -6,8 +6,8 @@
@finalout
@c %**end of header
@set UPDATED 26 February 2015
@set VERSION 1.7-pre1
@set UPDATED 23 May 2015
@set VERSION 1.7-rc1
@dircategory Data Compression
@direntry
@ -58,8 +58,7 @@ to copy, distribute and modify it.
Clzip is a lossless data compressor with a user interface similar to the
one of gzip or bzip2. Clzip is about as fast as gzip, compresses most
files more than bzip2, and is better than both from a data recovery
perspective. Clzip is a clean implementation of the LZMA
(Lempel-Ziv-Markov chain-Algorithm) "algorithm".
perspective.
Clzip uses the lzip file format; the files produced by clzip are fully
compatible with lzip-1.4 or newer, and can be rescued with lziprecover.
@ -162,23 +161,24 @@ multivolume compressed tar archives.
Clzip is able to compress and decompress streams of unlimited size by
automatically creating multi-member output. The members so created are
large, about 64 PiB each.
large, about 2 PiB each.
@node Algorithm
@chapter Algorithm
@cindex algorithm
There is no such thing as a "LZMA algorithm"; it is more like a "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 price than the one
currently used by lzip could be developed, and the resulting sequence
could also be coded using the LZMA coding scheme.
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.
Clzip currently implements two variants of the LZMA algorithm; fast (used
by option -0) and normal (used by all other compression levels).
Clzip currently implements two variants of the LZMA algorithm; fast
(used by option -0) 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
@ -245,7 +245,7 @@ clzip [@var{options}] [@var{files}]
Clzip supports the following options:
@table @samp
@table @code
@item -h
@itemx --help
Print an informative help message describing the options and exit.
@ -258,7 +258,7 @@ Print the version number of clzip on the standard output and exit.
@itemx --member-size=@var{bytes}
Set the member size limit to @var{bytes}. A small member size may
degrade compression ratio, so use it only when needed. Valid values
range from 100 kB to 64 PiB. Defaults to 64 PiB.
range from 100 kB to 2 PiB. Defaults to 2 PiB.
@item -c
@itemx --stdout
@ -441,13 +441,12 @@ A four byte string, identifying the lzip format, with the value "LZIP"
Just in case something needs to be modified in the future. 1 for now.
@item DS (coded dictionary size, 1 byte)
Lzip divides the distance between any two powers of 2 into 8 equally
spaced intervals, named "wedges". The dictionary size is calculated by
taking a power of 2 (the base size) and substracting from it a number of
wedges between 0 and 7. The size of a wedge is (base_size / 16).@*
The dictionary size is calculated by taking a power of 2 (the base size)
and substracting from it a fraction between 0/16 and 7/16 of the base
size.@*
Bits 4-0 contain the base 2 logarithm of the base size (12 to 29).@*
Bits 7-5 contain the number of wedges (0 to 7) to substract from the
base size to obtain the dictionary size.@*
Bits 7-5 contain the numerator of the fraction (0 to 7) to substract
from the base size to obtain the dictionary size.@*
Example: 0xD3 = 2^19 - 6 * 2^15 = 512 KiB - 6 * 32 KiB = 320 KiB@*
Valid values for dictionary size range from 4 KiB to 512 MiB.