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diff --git a/lib/Support/bzip2/README b/lib/Support/bzip2/README new file mode 100644 index 0000000..07505d8 --- /dev/null +++ b/lib/Support/bzip2/README @@ -0,0 +1,181 @@ + +This is the README for bzip2, a block-sorting file compressor, version +1.0.2. This version is fully compatible with the previous public +releases, versions 0.1pl2, 0.9.0, 0.9.5, 1.0.0 and 1.0.1. + +bzip2-1.0.2 is distributed under a BSD-style license. For details, +see the file LICENSE. + +Complete documentation is available in Postscript form (manual.ps), +PDF (manual.pdf, amazingly enough) or html (manual_toc.html). A +plain-text version of the manual page is available as bzip2.txt. +A statement about Y2K issues is now included in the file Y2K_INFO. + + +HOW TO BUILD -- UNIX + +Type `make'. This builds the library libbz2.a and then the +programs bzip2 and bzip2recover. Six self-tests are run. +If the self-tests complete ok, carry on to installation: + +To install in /usr/bin, /usr/lib, /usr/man and /usr/include, type + make install +To install somewhere else, eg, /xxx/yyy/{bin,lib,man,include}, type + make install PREFIX=/xxx/yyy +If you are (justifiably) paranoid and want to see what 'make install' +is going to do, you can first do + make -n install or + make -n install PREFIX=/xxx/yyy respectively. +The -n instructs make to show the commands it would execute, but +not actually execute them. + + +HOW TO BUILD -- UNIX, shared library libbz2.so. + +Do 'make -f Makefile-libbz2_so'. This Makefile seems to work for +Linux-ELF (RedHat 7.2 on an x86 box), with gcc. I make no claims +that it works for any other platform, though I suspect it probably +will work for most platforms employing both ELF and gcc. + +bzip2-shared, a client of the shared library, is also built, but not +self-tested. So I suggest you also build using the normal Makefile, +since that conducts a self-test. A second reason to prefer the +version statically linked to the library is that, on x86 platforms, +building shared objects makes a valuable register (%ebx) unavailable +to gcc, resulting in a slowdown of 10%-20%, at least for bzip2. + +Important note for people upgrading .so's from 0.9.0/0.9.5 to version +1.0.X. All the functions in the library have been renamed, from (eg) +bzCompress to BZ2_bzCompress, to avoid namespace pollution. +Unfortunately this means that the libbz2.so created by +Makefile-libbz2_so will not work with any program which used an older +version of the library. Sorry. I do encourage library clients to +make the effort to upgrade to use version 1.0, since it is both faster +and more robust than previous versions. + + +HOW TO BUILD -- Windows 95, NT, DOS, Mac, etc. + +It's difficult for me to support compilation on all these platforms. +My approach is to collect binaries for these platforms, and put them +on the master web page (http://sources.redhat.com/bzip2). Look there. +However (FWIW), bzip2-1.0.X is very standard ANSI C and should compile +unmodified with MS Visual C. If you have difficulties building, you +might want to read README.COMPILATION.PROBLEMS. + +At least using MS Visual C++ 6, you can build from the unmodified +sources by issuing, in a command shell: + nmake -f makefile.msc +(you may need to first run the MSVC-provided script VCVARS32.BAT + so as to set up paths to the MSVC tools correctly). + + +VALIDATION + +Correct operation, in the sense that a compressed file can always be +decompressed to reproduce the original, is obviously of paramount +importance. To validate bzip2, I used a modified version of Mark +Nelson's churn program. Churn is an automated test driver which +recursively traverses a directory structure, using bzip2 to compress +and then decompress each file it encounters, and checking that the +decompressed data is the same as the original. There are more details +in Section 4 of the user guide. + + + +Please read and be aware of the following: + +WARNING: + + This program (attempts to) compress data by performing several + non-trivial transformations on it. Unless you are 100% familiar + with *all* the algorithms contained herein, and with the + consequences of modifying them, you should NOT meddle with the + compression or decompression machinery. Incorrect changes can and + very likely *will* lead to disastrous loss of data. + + +DISCLAIMER: + + I TAKE NO RESPONSIBILITY FOR ANY LOSS OF DATA ARISING FROM THE + USE OF THIS PROGRAM, HOWSOEVER CAUSED. + + Every compression of a file implies an assumption that the + compressed file can be decompressed to reproduce the original. + Great efforts in design, coding and testing have been made to + ensure that this program works correctly. However, the complexity + of the algorithms, and, in particular, the presence of various + special cases in the code which occur with very low but non-zero + probability make it impossible to rule out the possibility of bugs + remaining in the program. DO NOT COMPRESS ANY DATA WITH THIS + PROGRAM UNLESS YOU ARE PREPARED TO ACCEPT THE POSSIBILITY, HOWEVER + SMALL, THAT THE DATA WILL NOT BE RECOVERABLE. + + That is not to say this program is inherently unreliable. Indeed, + I very much hope the opposite is true. bzip2 has been carefully + constructed and extensively tested. + + +PATENTS: + + To the best of my knowledge, bzip2 does not use any patented + algorithms. However, I do not have the resources available to + carry out a full patent search. Therefore I cannot give any + guarantee of the above statement. + +End of legalities. + + +WHAT'S NEW IN 0.9.0 (as compared to 0.1pl2) ? + + * Approx 10% faster compression, 30% faster decompression + * -t (test mode) is a lot quicker + * Can decompress concatenated compressed files + * Programming interface, so programs can directly read/write .bz2 files + * Less restrictive (BSD-style) licensing + * Flag handling more compatible with GNU gzip + * Much more documentation, i.e., a proper user manual + * Hopefully, improved portability (at least of the library) + +WHAT'S NEW IN 0.9.5 ? + + * Compression speed is much less sensitive to the input + data than in previous versions. Specifically, the very + slow performance caused by repetitive data is fixed. + * Many small improvements in file and flag handling. + * A Y2K statement. + +WHAT'S NEW IN 1.0.0 ? + + See the CHANGES file. + +WHAT'S NEW IN 1.0.2 ? + + See the CHANGES file. + + +I hope you find bzip2 useful. Feel free to contact me at + jseward@acm.org +if you have any suggestions or queries. Many people mailed me with +comments, suggestions and patches after the releases of bzip-0.15, +bzip-0.21, and bzip2 versions 0.1pl2, 0.9.0, 0.9.5, 1.0.0 and 1.0.1, +and the changes in bzip2 are largely a result of this feedback. +I thank you for your comments. + +At least for the time being, bzip2's "home" is (or can be reached via) +http://sources.redhat.com/bzip2. + +Julian Seward +jseward@acm.org + +Cambridge, UK (and what a great town this is!) + +18 July 1996 (version 0.15) +25 August 1996 (version 0.21) + 7 August 1997 (bzip2, version 0.1) +29 August 1997 (bzip2, version 0.1pl2) +23 August 1998 (bzip2, version 0.9.0) + 8 June 1999 (bzip2, version 0.9.5) + 4 Sept 1999 (bzip2, version 0.9.5d) + 5 May 2000 (bzip2, version 1.0pre8) +30 December 2001 (bzip2, version 1.0.2pre1)
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