diff options
Diffstat (limited to 'doc')
| -rw-r--r-- | doc/lzlib.info | 71 | ||||
| -rw-r--r-- | doc/lzlib.texi | 54 | ||||
| -rw-r--r-- | doc/minilzip.1 | 6 |
3 files changed, 93 insertions, 38 deletions
diff --git a/doc/lzlib.info b/doc/lzlib.info index 1344ced..2017f3f 100644 --- a/doc/lzlib.info +++ b/doc/lzlib.info @@ -11,7 +11,7 @@ File: lzlib.info, Node: Top, Next: Introduction, Up: (dir) Lzlib Manual ************ -This manual is for Lzlib (version 1.6-pre2, 30 January 2014). +This manual is for Lzlib (version 1.6-pre3, 30 March 2014). * Menu: @@ -45,9 +45,24 @@ 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 lzip file format is designed for long-term data archiving, taking +into account both data integrity and decoder availability: + + * The lzip format provides very safe integrity checking and some data + recovery means. The lziprecover program 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 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 lzip is copylefted, which guarantees that it will + remain free forever. The functions and variables forming the interface of the compression library are declared in the file 'lzlib.h'. Usage examples of the @@ -75,13 +90,23 @@ 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. + 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. Conversely, 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. + + Lzip currently implements two variants of the LZMA algorithm; fast +(used by option -0) and normal (used by all other compression levels). +Lzlib just implements the "normal" variant. + + 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 @@ -736,18 +761,18 @@ Concept index Tag Table: Node: Top220 -Node: Introduction1335 -Node: Library version3916 -Node: Buffering4561 -Node: Parameter limits5684 -Node: Compression functions6643 -Node: Decompression functions12856 -Node: Error codes19017 -Node: Error messages20956 -Node: Data format21535 -Node: Examples24184 -Node: Problems28267 -Node: Concept index28839 +Node: Introduction1333 +Node: Library version5247 +Node: Buffering5892 +Node: Parameter limits7015 +Node: Compression functions7974 +Node: Decompression functions14187 +Node: Error codes20348 +Node: Error messages22287 +Node: Data format22866 +Node: Examples25515 +Node: Problems29598 +Node: Concept index30170 End Tag Table diff --git a/doc/lzlib.texi b/doc/lzlib.texi index 88f0b16..658db32 100644 --- a/doc/lzlib.texi +++ b/doc/lzlib.texi @@ -6,8 +6,8 @@ @finalout @c %**end of header -@set UPDATED 30 January 2014 -@set VERSION 1.6-pre2 +@set UPDATED 30 March 2014 +@set VERSION 1.6-pre3 @dircategory Data Compression @direntry @@ -66,9 +66,29 @@ 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 lzip file format is designed for long-term data archiving, taking +into account both data integrity and decoder availability: + +@itemize @bullet +@item +The lzip format provides very safe integrity checking and some data +recovery means. The lziprecover program 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. + +@item +The lzip format is as simple as possible (but not simpler). The lzip +manual provides the 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. + +@item +Additionally lzip is copylefted, which guarantees that it will remain +free forever. +@end itemize The functions and variables forming the interface of the compression library are declared in the file @samp{lzlib.h}. Usage examples of the @@ -95,13 +115,23 @@ 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. +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. Conversely, 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. + +Lzip currently implements two variants of the LZMA algorithm; fast (used +by option -0) and normal (used by all other compression levels). Lzlib +just implements the "normal" variant. + +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 diff --git a/doc/minilzip.1 b/doc/minilzip.1 index 0535797..b61a79f 100644 --- a/doc/minilzip.1 +++ b/doc/minilzip.1 @@ -1,7 +1,7 @@ .\" DO NOT MODIFY THIS FILE! It was generated by help2man 1.37.1. -.TH MINILZIP "1" "January 2014" "Minilzip 1.6-pre2" "User Commands" +.TH MINILZIP "1" "March 2014" "minilzip 1.6-pre3" "User Commands" .SH NAME -Minilzip \- reduces the size of files +minilzip \- reduces the size of files .SH SYNOPSIS .B minilzip [\fIoptions\fR] [\fIfiles\fR] @@ -83,7 +83,7 @@ Report bugs to lzip\-bug@nongnu.org Lzlib home page: http://www.nongnu.org/lzip/lzlib.html .SH COPYRIGHT Copyright \(co 2014 Antonio Diaz Diaz. -Using Lzlib 1.6\-pre2 +Using lzlib 1.6\-pre3 License GPLv3+: GNU GPL version 3 or later <http://gnu.org/licenses/gpl.html> .br This is free software: you are free to change and redistribute it. |