Compress::Zlib

                                  Version 1.00

                                  14th Nov 1997

             Copyright (c) 1995/6/7 Paul Marquess. All rights reserved.
         This program is free software; you can redistribute it and/or
                modify it under the same terms as Perl itself.



DESCRIPTION
-----------

This module provides a Perl interface to part of the info-zip zlib
compression library.  For more details see the pod documentation
embedded in the file Zlib.pm.

PREREQUISITES
-------------

Before you can build Compress::Zlib you need to have the following
thing installed on your system:

    * Perl 5.003_05 or better. 
    * Info-zip zlib 1.0.2, 1.0.3 or 1.0.4 (note that this module is NOT
      compatable with versions of zlib <= 1.0.1).

      The zlib compression library is available at
      ftp://ftp.uu.net/pub/archiving/zip/zlib* and
      ftp://swrinde.nde.swri.edu/pub/png/src/zlib*.
      The zlib home page is http://quest.jpl.nasa.gov/zlib/.


BUILDING THE MODULE
-------------------

Assuming you have met all the prerequisites, building the module should
be relatively straightforward.

The only things you might have to change for building the module are
the names of the directories where the zlib library, libz, is installed
and the directory where zlib.h and zconf.h are stored. Edit Makefile.PL
and change ZLIB_LIB and ZLIB_INCLUDE if necessary.

The module can now be built using this sequence of commands:

    perl Makefile.PL
    make
    make test

INSTALLATION
------------

    make install

FEEDBACK
--------

I have tested Compress::Zlib on both SunOS 4.1.3 (Sun C compiler) and
Solaris 2.3 (Sun C compiler again). If you are building the module on
another architecture I would appreciate a note to tell me how you got
on. Although I am particularly interested to hear about any problems
you encounter when building the system, I would still like to hear from
you even if you don't.

Things I particularly would like to know

   * The Operating system name and version, e.g. SunOS 4.1.3
   * Architecture, e.g. Solaris
   * C compiler, e.g. gcc
   * Where there any warnings/errors printed by the C compiler? If so
     please send the exact output if possible.

CHANGES
-------

  0.1 - first alpha release. 2nd October 1995
  0.2 - Fixed a minor allocation problem in Zlib.xs
  0.3 - Added prototype specification.
  0.4 - Upgrade to support zlib 0.99 

	Added dictionary interface.

	Fixed bug in gzreadline - previously it would keep returning
	the same buffer. This bug was reported by Helmut Jarausch

	Removed dependancy to zutil.h and so dropped support for 
	
	    DEF_MEM_LEVEL (use MAX_MEM_LEVEL instead)
	    DEF_WBITS     (use MAX_WBITS instead)

  0.5 - Confirmed that no changes were necessary for zlib 1.0.3, or 1.0.4.

	The optional parameters for deflateInit and inflateInit can now
	be specified as an associative array in addition to a reference
	to an associative array. They can also accept the -Name
	syntax.

	gzopen can now optionally take a reference to an open
	filehandle in place of a filename. In this case it will call
	gzdopen.

	Added gzstream example script.
 
  1.00 - Fixed crc32 & adler32. They were very broken. 

      * The following functions can now take a scalar reference in
	place of a scalar for their buffer parameters:

    	    compress
    	    uncompress
    	    deflate
    	    inflate
    	    crc32
    	    adler32
 
	This should mean applications that make use of the module don't
	have to copy large buffers around.

 
      * Normally the inflate method consumes I<all> of the input buffer
	before returning. The exception to this is when inflate detects
	the end of the stream (Z_STREAM_END). In this case the input
	buffer need not be completely consumed. To allow processing of
	file formats that embed a deflation stream (e.g. zip, gzip),
	the inflate method now sets the buffer parameter to be what
	remains after inflation.

	When the return status is Z_STREAM_END, it will be what remains
	of the buffer (if any) after deflation. When the status is Z_OK
	it will be an empty string.

	This change means that the buffer parameter must be a lvalue.
 
      * Fixed crc32 and adler32. They were both very broken.

      * Added the Compress::Zlib::memGzip function.


Paul Marquess <pmarquess@bfsec.bt.co.uk>