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diff --git a/doc/plzip.info b/doc/plzip.info index 3a12bef..bf22e32 100644 --- a/doc/plzip.info +++ b/doc/plzip.info @@ -12,25 +12,25 @@ File: plzip.info, Node: Top, Next: Introduction, Up: (dir) Plzip Manual ************ -This manual is for Plzip (version 0.8, 17 January 2012). +This manual is for Plzip (version 1.0-rc1, 8 March 2013). * Menu: -* Introduction:: Purpose and features of plzip -* Invoking Plzip:: Command line interface -* Program Design:: Internal structure of plzip -* File Format:: Detailed format of the compressed file -* Problems:: Reporting bugs -* Concept Index:: Index of concepts +* Introduction:: Purpose and features of plzip +* Program Design:: Internal structure of plzip +* Invoking Plzip:: Command line interface +* File Format:: Detailed format of the compressed file +* Problems:: Reporting bugs +* Concept Index:: Index of concepts - Copyright (C) 2009, 2010, 2011, 2012 Antonio Diaz Diaz. + Copyright (C) 2009, 2010, 2011, 2012, 2013 Antonio Diaz Diaz. This manual is free documentation: you have unlimited permission to copy, distribute and modify it. -File: plzip.info, Node: Introduction, Next: Invoking Plzip, Prev: Top, Up: Top +File: plzip.info, Node: Introduction, Next: Program Design, Prev: Top, Up: Top 1 Introduction ************** @@ -81,15 +81,45 @@ processed. Be aware, though, that the check occurs upon decompression, so it can only tell you that something is wrong. It can't help you recover the original uncompressed data. + WARNING! Even if plzip is bug-free, other causes may result in a +corrupt compressed file (bugs in the system libraries, memory errors, +etc). Therefore, if the data you are going to compress is important, +give the `--keep' option to plzip and do not remove the original file +until you verify the compressed file with a command like +`plzip -cd file.lz | cmp file -'. + Return values: 0 for a normal exit, 1 for environmental problems (file not found, invalid flags, I/O errors, etc), 2 to indicate a corrupt or invalid input file, 3 for an internal consistency error (eg, bug) which caused plzip to panic. -File: plzip.info, Node: Invoking Plzip, Next: Program Design, Prev: Introduction, Up: Top +File: plzip.info, Node: Program Design, Next: Invoking Plzip, Prev: Introduction, Up: Top + +2 Program Design +**************** + +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, 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 -2 Invoking Plzip +3 Invoking Plzip **************** The format for running plzip is: @@ -149,7 +179,8 @@ The format for running plzip is: Set the number of worker threads. Valid values range from 1 to "as many as your system can support". If this option is not used, plzip tries to detect the number of processors in the system and - use it as default value. + use it as default value. `plzip --help' shows the system's default + value. `-o FILE' `--output=FILE' @@ -236,28 +267,17 @@ Z zettabyte (10^21) | Zi zebibyte (2^70) Y yottabyte (10^24) | Yi yobibyte (2^80) -File: plzip.info, Node: Program Design, Next: File Format, Prev: Invoking Plzip, Up: Top - -3 Program Design -**************** - -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. - - -File: plzip.info, Node: File Format, Next: Problems, Prev: Program Design, Up: Top +File: plzip.info, Node: File Format, Next: Problems, Prev: Invoking Plzip, Up: Top 4 File Format ************* -In the diagram below, a box like this: +Perfection is reached, not when there is no longer anything to add, but +when there is no longer anything to take away. +-- Antoine de Saint-Exupery + + + In the diagram below, a box like this: +---+ | | <-- the vertical bars might be missing +---+ @@ -286,15 +306,19 @@ additional information before, between, or after them. "LZIP". `VN (version number, 1 byte)' - Just in case something needs to be modified in the future. Valid - values are 0 and 1. Version 0 files are deprecated. They can - contain only one member and lack the `Member size' field. + Just in case something needs to be modified in the future. 1 for + now. `DS (coded dictionary size, 1 byte)' - Bits 4-0 contain the base 2 logarithm of the base dictionary size. - Bits 7-5 contain the number of "wedges" to substract from the base - dictionary size to obtain the dictionary size. The size of a wedge - is (base dictionary size / 16). + 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). + 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. + Example: 0xD3 = (2^19 - 6 * 2^15) = (512KiB - 6 * 32KiB) = 320KiB Valid values for dictionary size range from 4KiB to 512MiB. `Lzma stream' @@ -308,9 +332,9 @@ additional information before, between, or after them. Size of the uncompressed original data. `Member size (8 bytes)' - Total size of the member, including header and trailer. This - facilitates safe recovery of undamaged members from multi-member - files. + Total size of the member, including header and trailer. This field + acts as a distributed index, and facilitates safe recovery of + undamaged members from multi-member files. @@ -351,12 +375,12 @@ Concept Index Tag Table: Node: Top223 -Node: Introduction845 -Node: Invoking Plzip3641 -Node: Program Design8597 -Node: File Format9259 -Node: Problems11254 -Node: Concept Index11783 +Node: Introduction864 +Node: Program Design4030 +Node: Invoking Plzip5084 +Node: File Format10093 +Node: Problems12473 +Node: Concept Index13002 End Tag Table |