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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 2025-02-20 20:54:52 +01:00
parent cb8306f68b
commit f559c459b4
Signed by: daniel
GPG key ID: FBB4F0E80A80222F
17 changed files with 120 additions and 123 deletions
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30
doc/lzlib.texi
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@ -6,8 +6,8 @@
@finalout
@c %**end of header
@set UPDATED 24 February 2015
@set VERSION 1.7-pre1
@set UPDATED 23 May 2015
@set VERSION 1.7-rc1
@dircategory Data Compression
@direntry
@ -126,13 +126,14 @@ 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.
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.
Lzlib currently implements two variants of the LZMA algorithm; fast
(used by option -0 of minilzip) and normal (used by all other
@ -667,13 +668,12 @@ 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.