zlib 1.0.9 is a general purpose data compression library. All the code is thread safe. The data format used by the zlib library is described by RFCs (Request for Comments) 1950 to 1952 in the files ftp://ds.internic.net/rfc/rfc1950.txt (zlib format), rfc1951.txt (deflate format) and rfc1952.txt (gzip format). These documents are also available in other formats from ftp://ftp.uu.net/graphics/png/documents/zlib/zdoc-index.html All functions of the compression library are documented in the file zlib.h (volunteer to write man pages welcome, contact jloup@gzip.org). A usage example of the library is given in the file example.c which also tests that the library is working correctly. Another example is given in the file minigzip.c. The compression library itself is composed of all source files except example.c and minigzip.c. To compile all files and run the test program, follow the instructions given at the top of Makefile. In short "make test; make install" should work for most machines. For MSDOS, use one of the special makefiles such as Makefile.msc; for VMS, use Make_vms.com or descrip.mms. Questions about zlib should be sent to or, if this fails, to the addresses given below in the Copyright section. The zlib home page is http://www.cdrom.com/pub/infozip/zlib/ The official zlib ftp site is ftp://ftp.cdrom.com/pub/infozip/zlib/ Mark Nelson wrote an article about zlib for the Jan. 1997 issue of Dr. Dobb's Journal; a copy of the article is available in http://web2.airmail.net/markn/articles/zlibtool/zlibtool.htm The changes made in version 1.0.9 are documented in the file ChangeLog. The main changes since 1.0.8 are: - added gzputs and gzgets functions - do not clear eof flag in gzseek (Mark Diekhans) - fix gzseek for files in transparent mode (Mark Diekhans) - do not assume that vsprintf returns the number of bytes written (Jens Krinke) - replace EXPORT with ZEXPORT to avoid conflict with other programs - added compress2 in zconf.h, zlib.def, zlib.dnt - new asm code from Gilles Vollant in contrib/asm386 - simplify the inflate code (Mark): . Replace ZALLOC's in huft_build() with single ZALLOC in inflate_blocks_new() . ZALLOC the length list in inflate_trees_fixed() instead of using stack . ZALLOC the value area for huft_build() instead of using stack . Simplify Z_FINISH check in inflate() Unsupported third party contributions are provided in directory "contrib". A Java implementation of zlib is available in the Java Development Kit 1.1 http://www.javasoft.com/products/JDK/1.1/docs/api/Package-java.util.zip.html See the zlib home page http://www.cdrom.com/pub/infozip/zlib/ for details. A Perl interface to zlib written by Paul Marquess is in the CPAN (Comprehensive Perl Archive Network) sites, such as: ftp://ftp.cis.ufl.edu/pub/perl/CPAN/modules/by-module/Compress/Compress-Zlib* A Python interface to zlib written by A.M. Kuchling is available from the Python Software Association sites, such as: ftp://ftp.python.org/pub/python/contrib/Encoding/zlib*.tar.gz Notes for some targets: - To build a Windows DLL version, include in a DLL project zlib.def, zlib.rc and all .c files except example.c and minigzip.c; compile with -DZLIB_DLL The zlib DLL support was initially done by Alessandro Iacopetti and is now maintained by Gilles Vollant . Check the zlib DLL home page at http://www.winimage.com/zLibDll From Visual Basic, you can call the DLL functions which do not take a structure as argument: compress, uncompress and all gz* functions. See contrib/visual-basic.txt for more information. I don't know how to handle structures in Visual Basic, sorry. - For 64-bit Irix, deflate.c must be compiled without any optimization. With -O, one libpng test fails. The test works in 32 bit mode (with the -n32 compiler flag). The compiler bug has been reported to SGI. - zlib doesn't work with gcc 2.6.3 on a DEC 3000/300LX under OSF/1 2.1 it works when compiled with cc. - zlib doesn't work on HP-UX 9.05 with some versions of /bin/cc. It works with other compilers. Use "make test" to check your compiler. - For shared memory multiprocessors, the decompression code assumes that writes to pointers are atomic. Also the functions zalloc and zfree passed to deflateInit must be multi-threaded in this case. - gzdopen is not supported on RISCOS, BEOS and Mac - For Turbo C the small model is supported only with reduced performance to avoid any far allocation; it was tested with -DMAX_WBITS=11 -DMAX_MEM_LEVEL=3 Acknowledgments: The deflate format used by zlib was defined by Phil Katz. The deflate and zlib specifications were written by Peter Deutsch. Thanks to all the people who reported problems and suggested various improvements in zlib; they are too numerous to cite here. Copyright notice: (C) 1995-1998 Jean-loup Gailly and Mark Adler This software is provided 'as-is', without any express or implied warranty. In no event will the authors be held liable for any damages arising from the use of this software. Permission is granted to anyone to use this software for any purpose, including commercial applications, and to alter it and redistribute it freely, subject to the following restrictions: 1. The origin of this software must not be misrepresented; you must not claim that you wrote the original software. If you use this software in a product, an acknowledgment in the product documentation would be appreciated but is not required. 2. Altered source versions must be plainly marked as such, and must not be misrepresented as being the original software. 3. This notice may not be removed or altered from any source distribution. Jean-loup Gailly Mark Adler jloup@gzip.org madler@alumni.caltech.edu If you use the zlib library in a product, we would appreciate *not* receiving lengthy legal documents to sign. The sources are provided for free but without warranty of any kind. The library has been entirely written by Jean-loup Gailly and Mark Adler; it does not include third-party code. If you redistribute modified sources, we would appreciate that you include in the file ChangeLog history information documenting your changes.