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Merging upstream version 1.4.

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Signed-off-by: Daniel Baumann <daniel@debian.org>
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Daniel Baumann 2025-02-24 04:10:09 +01:00
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GPG key ID: FBB4F0E80A80222F
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doc/plzip.info
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@ -11,13 +11,13 @@ File: plzip.info, Node: Top, Next: Introduction, Up: (dir)
Plzip Manual
************
This manual is for Plzip (version 1.4-rc1, 23 May 2015).
This manual is for Plzip (version 1.4, 9 July 2015).
* Menu:
* Introduction:: Purpose and features of plzip
* Program design:: Internal structure of plzip
* Invoking plzip:: Command line interface
* Program design:: Internal structure of plzip
* File format:: Detailed format of the compressed file
* Memory requirements:: Memory required to compress and decompress
* Minimum file sizes:: Minimum file sizes required for full speed
@ -31,7 +31,7 @@ This manual is for Plzip (version 1.4-rc1, 23 May 2015).
copy, distribute and modify it.

File: plzip.info, Node: Introduction, Next: Program design, Prev: Top, Up: Top
File: plzip.info, Node: Introduction, Next: Invoking plzip, Prev: Top, Up: Top
1 Introduction
**************
@ -59,7 +59,8 @@ availability:
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.
merging of damaged copies of a file. *note Data safety:
(lziprecover)Data safety.
* The lzip format is as simple as possible (but not simpler). The
lzip manual provides the code of a simple decompressor along with
@ -122,43 +123,9 @@ until you verify the compressed file with a command like
'plzip -cd file.lz | cmp file -'.

File: plzip.info, Node: Program design, Next: Invoking plzip, Prev: Introduction, Up: Top
File: plzip.info, Node: Invoking plzip, Next: Program design, Prev: Introduction, Up: Top
2 Program design
****************
When compressing, plzip divides the input file into chunks and
compresses as many chunks simultaneously as worker threads are chosen,
creating a multi-member compressed file.
When decompressing, plzip decompresses as many members
simultaneously as worker threads are chosen. Files that were compressed
with lzip will not be decompressed faster than using lzip (unless the
'-b' option was used) because lzip usually produces single-member
files, which can't be decompressed in parallel.
For each input file, a splitter thread and several worker threads are
created, acting the main thread as muxer (multiplexer) thread. A "packet
courier" takes care of data transfers among threads and limits the
maximum number of data blocks (packets) being processed simultaneously.
The splitter reads data blocks from the input file, and distributes
them to the workers. The workers (de)compress the blocks received from
the splitter. The muxer collects processed packets from the workers, and
writes them to the output file.
When decompressing from a regular file, the splitter is removed and
the workers read directly from the input file. If the output file is
also a regular file, the muxer is also removed and the workers write
directly to the output file. With these optimizations, the use of RAM
is greatly reduced and the decompression speed of large files with many
members is only limited by the number of processors available and by
I/O speed.

File: plzip.info, Node: Invoking plzip, Next: File format, Prev: Program design, Up: Top
3 Invoking plzip
2 Invoking plzip
****************
The format for running plzip is:
@ -199,7 +166,7 @@ The format for running plzip is:
'-F'
'--recompress'
Force recompression of files whose name already has the '.lz' or
Force re-compression of files whose name already has the '.lz' or
'.tlz' suffix.
'-k'
@ -318,7 +285,41 @@ invalid input file, 3 for an internal consistency error (eg, bug) which
caused plzip to panic.

File: plzip.info, Node: File format, Next: Memory requirements, Prev: Invoking plzip, Up: Top
File: plzip.info, Node: Program design, Next: File format, Prev: Invoking plzip, Up: Top
3 Program design
****************
When compressing, plzip divides the input file into chunks and
compresses as many chunks simultaneously as worker threads are chosen,
creating a multi-member compressed file.
When decompressing, plzip decompresses as many members
simultaneously as worker threads are chosen. Files that were compressed
with lzip will not be decompressed faster than using lzip (unless the
'-b' option was used) because lzip usually produces single-member
files, which can't be decompressed in parallel.
For each input file, a splitter thread and several worker threads are
created, acting the main thread as muxer (multiplexer) thread. A "packet
courier" takes care of data transfers among threads and limits the
maximum number of data blocks (packets) being processed simultaneously.
The splitter reads data blocks from the input file, and distributes
them to the workers. The workers (de)compress the blocks received from
the splitter. The muxer collects processed packets from the workers, and
writes them to the output file.
When decompressing from a regular file, the splitter is removed and
the workers read directly from the input file. If the output file is
also a regular file, the muxer is also removed and the workers write
directly to the output file. With these optimizations, the use of RAM
is greatly reduced and the decompression speed of large files with many
members is only limited by the number of processors available and by
I/O speed.

File: plzip.info, Node: File format, Next: Memory requirements, Prev: Program design, Up: Top
4 File format
*************
@ -398,15 +399,16 @@ The amount of memory required *per thread* is approximately the
following:
* For compression at level -0; 1.5 MiB plus 3 times the data size
(*note --data-size::). About 4.5 MiB.
(*note --data-size::). Default is 4.5 MiB.
* For compression at other levels; 11 times the dictionary size plus
3 times the data size. Default is 136 MiB.
* For decompression of a regular (seekable) file to another regular
file, or for testing of a regular file; the dictionary size. Note
that regular files with more than 1024 bytes of trailing garbage
are treated as non-seekable.
file, or for testing of a regular file; the dictionary size.
(Note that regular files with more than 1024 bytes of trailing
garbage are treated as non-seekable).
* For testing of a non-seekable file or of standard input; the
dictionary size plus up to 5 MiB.
@ -493,15 +495,15 @@ Concept index

Tag Table:
Node: Top221
Node: Introduction988
Node: Program design5285
Node: Invoking plzip6874
Ref: --data-size7288
Node: File format12512
Node: Memory requirements14925
Node: Minimum file sizes16029
Node: Problems17951
Node: Concept index18487
Node: Introduction984
Node: Invoking plzip5332
Ref: --data-size5747
Node: Program design10972
Node: File format12560
Node: Memory requirements14973
Node: Minimum file sizes16085
Node: Problems18007
Node: Concept index18543

End Tag Table