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

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