sdk/lib/3rdparty/bzip2/README

   1
   2 This is the README for bzip2/libzip2.
   3 This version is fully compatible with the previous public releases.
   4
   5 ------------------------------------------------------------------
   6 This file is part of bzip2/libbzip2, a program and library for
   7 lossless, block-sorting data compression.
   8
   9 bzip2/libbzip2 version 1.0.6 of 6 September 2010
  10 Copyright (C) 1996-2010 Julian Seward <jseward@bzip.org>
  11
  12 Please read the WARNING, DISCLAIMER and PATENTS sections in this file.
  13
  14 This program is released under the terms of the license contained
  15 in the file LICENSE.
  16 ------------------------------------------------------------------
  17
  18 Complete documentation is available in Postscript form (manual.ps),
  19 PDF (manual.pdf) or html (manual.html).  A plain-text version of the
  20 manual page is available as bzip2.txt.
  21
  22
  23 HOW TO BUILD -- UNIX
  24
  25 Type 'make'.  This builds the library libbz2.a and then the programs
  26 bzip2 and bzip2recover.  Six self-tests are run.  If the self-tests
  27 complete ok, carry on to installation:
  28
  29 To install in /usr/local/bin, /usr/local/lib, /usr/local/man and
  30 /usr/local/include, type
  31
  32    make install
  33
  34 To install somewhere else, eg, /xxx/yyy/{bin,lib,man,include}, type
  35
  36    make install PREFIX=/xxx/yyy
  37
  38 If you are (justifiably) paranoid and want to see what 'make install'
  39 is going to do, you can first do
  40
  41    make -n install                      or
  42    make -n install PREFIX=/xxx/yyy      respectively.
  43
  44 The -n instructs make to show the commands it would execute, but not
  45 actually execute them.
  46
  47
  48 HOW TO BUILD -- UNIX, shared library libbz2.so.
  49
  50 Do 'make -f Makefile-libbz2_so'.  This Makefile seems to work for
  51 Linux-ELF (RedHat 7.2 on an x86 box), with gcc.  I make no claims
  52 that it works for any other platform, though I suspect it probably
  53 will work for most platforms employing both ELF and gcc.
  54
  55 bzip2-shared, a client of the shared library, is also built, but not
  56 self-tested.  So I suggest you also build using the normal Makefile,
  57 since that conducts a self-test.  A second reason to prefer the
  58 version statically linked to the library is that, on x86 platforms,
  59 building shared objects makes a valuable register (%ebx) unavailable
  60 to gcc, resulting in a slowdown of 10%-20%, at least for bzip2.
  61
  62 Important note for people upgrading .so's from 0.9.0/0.9.5 to version
  63 1.0.X.  All the functions in the library have been renamed, from (eg)
  64 bzCompress to BZ2_bzCompress, to avoid namespace pollution.
  65 Unfortunately this means that the libbz2.so created by
  66 Makefile-libbz2_so will not work with any program which used an older
  67 version of the library.  I do encourage library clients to make the
  68 effort to upgrade to use version 1.0, since it is both faster and more
  69 robust than previous versions.
  70
  71
  72 HOW TO BUILD -- Windows 95, NT, DOS, Mac, etc.
  73
  74 It's difficult for me to support compilation on all these platforms.
  75 My approach is to collect binaries for these platforms, and put them
  76 on the master web site (http://www.bzip.org).  Look there.  However
  77 (FWIW), bzip2-1.0.X is very standard ANSI C and should compile
  78 unmodified with MS Visual C.  If you have difficulties building, you
  79 might want to read README.COMPILATION.PROBLEMS.
  80
  81 At least using MS Visual C++ 6, you can build from the unmodified
  82 sources by issuing, in a command shell:
  83
  84    nmake -f makefile.msc
  85
  86 (you may need to first run the MSVC-provided script VCVARS32.BAT
  87  so as to set up paths to the MSVC tools correctly).
  88
  89
  90 VALIDATION
  91
  92 Correct operation, in the sense that a compressed file can always be
  93 decompressed to reproduce the original, is obviously of paramount
  94 importance.  To validate bzip2, I used a modified version of Mark
  95 Nelson's churn program.  Churn is an automated test driver which
  96 recursively traverses a directory structure, using bzip2 to compress
  97 and then decompress each file it encounters, and checking that the
  98 decompressed data is the same as the original.
  99
 100
 101
 102 Please read and be aware of the following:
 103
 104 WARNING:
 105
 106    This program and library (attempts to) compress data by
 107    performing several non-trivial transformations on it.
 108    Unless you are 100% familiar with *all* the algorithms
 109    contained herein, and with the consequences of modifying them,
 110    you should NOT meddle with the compression or decompression
 111    machinery.  Incorrect changes can and very likely *will*
 112    lead to disastrous loss of data.
 113
 114
 115 DISCLAIMER:
 116
 117    I TAKE NO RESPONSIBILITY FOR ANY LOSS OF DATA ARISING FROM THE
 118    USE OF THIS PROGRAM/LIBRARY, HOWSOEVER CAUSED.
 119
 120    Every compression of a file implies an assumption that the
 121    compressed file can be decompressed to reproduce the original.
 122    Great efforts in design, coding and testing have been made to
 123    ensure that this program works correctly.  However, the complexity
 124    of the algorithms, and, in particular, the presence of various
 125    special cases in the code which occur with very low but non-zero
 126    probability make it impossible to rule out the possibility of bugs
 127    remaining in the program.  DO NOT COMPRESS ANY DATA WITH THIS
 128    PROGRAM UNLESS YOU ARE PREPARED TO ACCEPT THE POSSIBILITY, HOWEVER
 129    SMALL, THAT THE DATA WILL NOT BE RECOVERABLE.
 130
 131    That is not to say this program is inherently unreliable.
 132    Indeed, I very much hope the opposite is true.  bzip2/libbzip2
 133    has been carefully constructed and extensively tested.
 134
 135
 136 PATENTS:
 137
 138    To the best of my knowledge, bzip2/libbzip2 does not use any
 139    patented algorithms.  However, I do not have the resources
 140    to carry out a patent search.  Therefore I cannot give any
 141    guarantee of the above statement.
 142
 143
 144
 145 WHAT'S NEW IN 0.9.0 (as compared to 0.1pl2) ?
 146
 147    * Approx 10% faster compression, 30% faster decompression
 148    * -t (test mode) is a lot quicker
 149    * Can decompress concatenated compressed files
 150    * Programming interface, so programs can directly read/write .bz2 files
 151    * Less restrictive (BSD-style) licensing
 152    * Flag handling more compatible with GNU gzip
 153    * Much more documentation, i.e., a proper user manual
 154    * Hopefully, improved portability (at least of the library)
 155
 156 WHAT'S NEW IN 0.9.5 ?
 157
 158    * Compression speed is much less sensitive to the input
 159      data than in previous versions.  Specifically, the very
 160      slow performance caused by repetitive data is fixed.
 161    * Many small improvements in file and flag handling.
 162    * A Y2K statement.
 163
 164 WHAT'S NEW IN 1.0.0 ?
 165
 166    See the CHANGES file.
 167
 168 WHAT'S NEW IN 1.0.2 ?
 169
 170    See the CHANGES file.
 171
 172 WHAT'S NEW IN 1.0.3 ?
 173
 174    See the CHANGES file.
 175
 176 WHAT'S NEW IN 1.0.4 ?
 177
 178    See the CHANGES file.
 179
 180 WHAT'S NEW IN 1.0.5 ?
 181
 182    See the CHANGES file.
 183
 184 WHAT'S NEW IN 1.0.6 ?
 185
 186    See the CHANGES file.
 187
 188
 189 I hope you find bzip2 useful.  Feel free to contact me at
 190    jseward@bzip.org
 191 if you have any suggestions or queries.  Many people mailed me with
 192 comments, suggestions and patches after the releases of bzip-0.15,
 193 bzip-0.21, and bzip2 versions 0.1pl2, 0.9.0, 0.9.5, 1.0.0, 1.0.1,
 194 1.0.2 and 1.0.3, and the changes in bzip2 are largely a result of this
 195 feedback.  I thank you for your comments.
 196
 197 bzip2's "home" is http://www.bzip.org/
 198
 199 Julian Seward
 200 jseward@bzip.org
 201 Cambridge, UK.
 202
 203 18     July 1996 (version 0.15)
 204 25   August 1996 (version 0.21)
 205  7   August 1997 (bzip2, version 0.1)
 206 29   August 1997 (bzip2, version 0.1pl2)
 207 23   August 1998 (bzip2, version 0.9.0)
 208  8     June 1999 (bzip2, version 0.9.5)
 209  4     Sept 1999 (bzip2, version 0.9.5d)
 210  5      May 2000 (bzip2, version 1.0pre8)
 211 30 December 2001 (bzip2, version 1.0.2pre1)
 212 15 February 2005 (bzip2, version 1.0.3)
 213 20 December 2006 (bzip2, version 1.0.4)
 214 10 December 2007 (bzip2, version 1.0.5)
 215  6     Sept 2010 (bzip2, version 1.0.6)