128 lines
6.0 KiB
Plaintext
128 lines
6.0 KiB
Plaintext
zlib 1.1.1 is a general purpose data compression library. All the code
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is thread safe. The data format used by the zlib library
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is described by RFCs (Request for Comments) 1950 to 1952 in the files
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ftp://ds.internic.net/rfc/rfc1950.txt (zlib format), rfc1951.txt (deflate
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format) and rfc1952.txt (gzip format). These documents are also available in
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other formats from ftp://ftp.uu.net/graphics/png/documents/zlib/zdoc-index.html
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All functions of the compression library are documented in the file zlib.h
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(volunteer to write man pages welcome, contact jloup@gzip.org). A usage
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example of the library is given in the file example.c which also tests that
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the library is working correctly. Another example is given in the file
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minigzip.c. The compression library itself is composed of all source files
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except example.c and minigzip.c.
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To compile all files and run the test program, follow the instructions
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given at the top of Makefile. In short "make test; make install"
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should work for most machines. For MSDOS, use one of the special
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makefiles such as Makefile.msc; for VMS, use Make_vms.com or descrip.mms.
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Questions about zlib should be sent to <zlib@quest.jpl.nasa.gov> or,
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if this fails, to the addresses given below in the Copyright section.
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The zlib home page is http://www.cdrom.com/pub/infozip/zlib/
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The official zlib ftp site is ftp://ftp.cdrom.com/pub/infozip/zlib/
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Mark Nelson wrote an article about zlib for the Jan. 1997 issue of
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Dr. Dobb's Journal; a copy of the article is available in
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http://web2.airmail.net/markn/articles/zlibtool/zlibtool.htm
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The changes made in version 1.1.1 are documented in the file ChangeLog.
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The main changes since 1.1.0 are:
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- fix macros _tr_tally_* in deflate.h for debug mode (Glenn Randers-Pehrson)
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- remove block truncation heuristic which had very marginal effect for zlib
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(smaller lit_bufsize than in gzip 1.2.4) and degraded a little the
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compression ratio on some files. This also allows inlining _tr_tally for
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matches in deflate_slow.
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Unsupported third party contributions are provided in directory "contrib".
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A Java implementation of zlib is available in the Java Development Kit 1.1
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http://www.javasoft.com/products/JDK/1.1/docs/api/Package-java.util.zip.html
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See the zlib home page http://www.cdrom.com/pub/infozip/zlib/ for details.
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A Perl interface to zlib written by Paul Marquess <pmarquess@bfsec.bt.co.uk>
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is in the CPAN (Comprehensive Perl Archive Network) sites, such as:
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ftp://ftp.cis.ufl.edu/pub/perl/CPAN/modules/by-module/Compress/Compress-Zlib*
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A Python interface to zlib written by A.M. Kuchling <amk@magnet.com>
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is available from the Python Software Association sites, such as:
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ftp://ftp.python.org/pub/python/contrib/Encoding/zlib*.tar.gz
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An experimental package to read files in .zip format, written on top of
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zlib by Gilles Vollant <info@winimage.com>, is available at
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http://www.winimage.com/zLibDll/unzip.html
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Notes for some targets:
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- To build a Windows DLL version, include in a DLL project zlib.def, zlib.rc
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and all .c files except example.c and minigzip.c; compile with -DZLIB_DLL
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The zlib DLL support was initially done by Alessandro Iacopetti and is
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now maintained by Gilles Vollant <info@winimage.com>. Check the zlib DLL
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home page at http://www.winimage.com/zLibDll
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From Visual Basic, you can call the DLL functions which do not take
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a structure as argument: compress, uncompress and all gz* functions.
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See contrib/visual-basic.txt for more information.
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I don't know how to handle structures in Visual Basic, sorry.
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- For 64-bit Irix, deflate.c must be compiled without any optimization.
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With -O, one libpng test fails. The test works in 32 bit mode (with
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the -n32 compiler flag). The compiler bug has been reported to SGI.
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- zlib doesn't work with gcc 2.6.3 on a DEC 3000/300LX under OSF/1 2.1
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it works when compiled with cc.
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- zlib doesn't work on HP-UX 9.05 with some versions of /bin/cc. It works
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with other compilers. Use "make test" to check your compiler.
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- For shared memory multiprocessors, the decompression code assumes that
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writes to pointers are atomic. Also the functions zalloc and zfree passed
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to deflateInit must be multi-threaded in this case.
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- gzdopen is not supported on RISCOS, BEOS and by some Mac compilers.
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- For Turbo C the small model is supported only with reduced performance to
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avoid any far allocation; it was tested with -DMAX_WBITS=11 -DMAX_MEM_LEVEL=3
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Acknowledgments:
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The deflate format used by zlib was defined by Phil Katz. The deflate
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and zlib specifications were written by Peter Deutsch. Thanks to all the
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people who reported problems and suggested various improvements in zlib;
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they are too numerous to cite here.
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Copyright notice:
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(C) 1995-1998 Jean-loup Gailly and Mark Adler
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This software is provided 'as-is', without any express or implied
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warranty. In no event will the authors be held liable for any damages
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arising from the use of this software.
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Permission is granted to anyone to use this software for any purpose,
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including commercial applications, and to alter it and redistribute it
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freely, subject to the following restrictions:
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1. The origin of this software must not be misrepresented; you must not
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claim that you wrote the original software. If you use this software
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in a product, an acknowledgment in the product documentation would be
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appreciated but is not required.
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2. Altered source versions must be plainly marked as such, and must not be
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misrepresented as being the original software.
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3. This notice may not be removed or altered from any source distribution.
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Jean-loup Gailly Mark Adler
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jloup@gzip.org madler@alumni.caltech.edu
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If you use the zlib library in a product, we would appreciate *not*
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receiving lengthy legal documents to sign. The sources are provided
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for free but without warranty of any kind. The library has been
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entirely written by Jean-loup Gailly and Mark Adler; it does not
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include third-party code.
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If you redistribute modified sources, we would appreciate that you include
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in the file ChangeLog history information documenting your changes.
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