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Compress::Zlib(3)	       User Contributed Perl Documentation		Compress::Zlib(3)

NAME
       Compress::Zlib - Interface to zlib compression library

SYNOPSIS
	   use Compress::Zlib ;

	   ($d, $status) = deflateInit( [OPT] ) ;
	   $status = $d->deflate($input, $output) ;
	   $status = $d->flush([$flush_type]) ;
	   $d->deflateParams(OPTS) ;
	   $d->deflateTune(OPTS) ;
	   $d->dict_adler() ;
	   $d->crc32() ;
	   $d->adler32() ;
	   $d->total_in() ;
	   $d->total_out() ;
	   $d->msg() ;
	   $d->get_Strategy();
	   $d->get_Level();
	   $d->get_BufSize();

	   ($i, $status) = inflateInit( [OPT] ) ;
	   $status = $i->inflate($input, $output [, $eof]) ;
	   $status = $i->inflateSync($input) ;
	   $i->dict_adler() ;
	   $d->crc32() ;
	   $d->adler32() ;
	   $i->total_in() ;
	   $i->total_out() ;
	   $i->msg() ;
	   $d->get_BufSize();

	   $dest = compress($source) ;
	   $dest = uncompress($source) ;

	   $gz = gzopen($filename or filehandle, $mode) ;
	   $bytesread = $gz->gzread($buffer [,$size]) ;
	   $bytesread = $gz->gzreadline($line) ;
	   $byteswritten = $gz->gzwrite($buffer) ;
	   $status = $gz->gzflush($flush) ;
	   $offset = $gz->gztell() ;
	   $status = $gz->gzseek($offset, $whence) ;
	   $status = $gz->gzclose() ;
	   $status = $gz->gzeof() ;
	   $status = $gz->gzsetparams($level, $strategy) ;
	   $errstring = $gz->gzerror() ;
	   $gzerrno

	   $dest = Compress::Zlib::memGzip($buffer) ;
	   $dest = Compress::Zlib::memGunzip($buffer) ;

	   $crc = adler32($buffer [,$crc]) ;
	   $crc = crc32($buffer [,$crc]) ;

	   $crc = adler32_combine($crc1, $crc2, $len2)l
	   $crc = crc32_combine($adler1, $adler2, $len2)

	   my $version = Compress::Raw::Zlib::zlib_version();

DESCRIPTION
       The Compress::Zlib module provides a Perl interface to the zlib compression library (see
       "AUTHOR" for details about where to get zlib).

       The "Compress::Zlib" module can be split into two general areas of functionality, namely a
       simple read/write interface to gzip files and a low-level in-memory
       compression/decompression interface.

       Each of these areas will be discussed in the following sections.

   Notes for users of Compress::Zlib version 1
       The main change in "Compress::Zlib" version 2.x is that it does not now interface directly
       to the zlib library. Instead it uses the "IO::Compress::Gzip" and "IO::Uncompress::Gunzip"
       modules for reading/writing gzip files, and the "Compress::Raw::Zlib" module for some low-
       level zlib access.

       The interface provided by version 2 of this module should be 100% backward compatible with
       version 1. If you find a difference in the expected behaviour please contact the author
       (See "AUTHOR"). See "GZIP INTERFACE"

       With the creation of the "IO::Compress" and "IO::Uncompress" modules no new features are
       planned for "Compress::Zlib" - the new modules do everything that "Compress::Zlib" does
       and then some. Development on "Compress::Zlib" will be limited to bug fixes only.

       If you are writing new code, your first port of call should be one of the new
       "IO::Compress" or "IO::Uncompress" modules.

GZIP INTERFACE
       A number of functions are supplied in zlib for reading and writing gzip files that conform
       to RFC 1952. This module provides an interface to most of them.

       If you have previously used "Compress::Zlib" 1.x, the following enhancements/changes have
       been made to the "gzopen" interface:

       1.   If you want to open either STDIN or STDOUT with "gzopen", you can now optionally use
	    the special filename ""-"" as a synonym for "\*STDIN" and "\*STDOUT".

       2.   In "Compress::Zlib" version 1.x, "gzopen" used the zlib library to open the
	    underlying file. This made things especially tricky when a Perl filehandle was passed
	    to "gzopen". Behind the scenes the numeric C file descriptor had to be extracted from
	    the Perl filehandle and this passed to the zlib library.

	    Apart from being non-portable to some operating systems, this made it difficult to
	    use "gzopen" in situations where you wanted to extract/create a gzip data stream that
	    is embedded in a larger file, without having to resort to opening and closing the
	    file multiple times.

	    It also made it impossible to pass a perl filehandle that wasn't associated with a
	    real filesystem file, like, say, an "IO::String".

	    In "Compress::Zlib" version 2.x, the "gzopen" interface has been completely rewritten
	    to use the IO::Compress::Gzip for writing gzip files and IO::Uncompress::Gunzip for
	    reading gzip files. None of the limitations mentioned above apply.

       3.   Addition of "gzseek" to provide a restricted "seek" interface.

       4.   Added "gztell".

       A more complete and flexible interface for reading/writing gzip files/buffers is included
       with the module "IO-Compress-Zlib". See IO::Compress::Gzip and IO::Uncompress::Gunzip for
       more details.

       $gz = gzopen($filename, $mode)
       $gz = gzopen($filehandle, $mode)
	    This function opens either the gzip file $filename for reading or writing or attaches
	    to the opened filehandle, $filehandle.  It returns an object on success and "undef"
	    on failure.

	    When writing a gzip file this interface will always create the smallest possible gzip
	    header (exactly 10 bytes). If you want greater control over what gets stored in the
	    gzip header (like the original filename or a comment) use IO::Compress::Gzip instead.
	    Similarly if you want to read the contents of the gzip header use
	    IO::Uncompress::Gunzip.

	    The second parameter, $mode, is used to specify whether the file is opened for
	    reading or writing and to optionally specify a compression level and compression
	    strategy when writing. The format of the $mode parameter is similar to the mode
	    parameter to the 'C' function "fopen", so "rb" is used to open for reading, "wb" for
	    writing and "ab" for appending (writing at the end of the file).

	    To specify a compression level when writing, append a digit between 0 and 9 to the
	    mode string -- 0 means no compression and 9 means maximum compression.  If no
	    compression level is specified Z_DEFAULT_COMPRESSION is used.

	    To specify the compression strategy when writing, append 'f' for filtered data, 'h'
	    for Huffman only compression, or 'R' for run-length encoding.  If no strategy is
	    specified Z_DEFAULT_STRATEGY is used.

	    So, for example, "wb9" means open for writing with the maximum compression using the
	    default strategy and "wb4R" means open for writing with compression level 4 and run-
	    length encoding.

	    Refer to the zlib documentation for the exact format of the $mode parameter.

       $bytesread = $gz->gzread($buffer [, $size]) ;
	    Reads $size bytes from the compressed file into $buffer. If $size is not specified,
	    it will default to 4096. If the scalar $buffer is not large enough, it will be
	    extended automatically.

	    Returns the number of bytes actually read. On EOF it returns 0 and in the case of an
	    error, -1.

       $bytesread = $gz->gzreadline($line) ;
	    Reads the next line from the compressed file into $line.

	    Returns the number of bytes actually read. On EOF it returns 0 and in the case of an
	    error, -1.

	    It is legal to intermix calls to "gzread" and "gzreadline".

	    To maintain backward compatibility with version 1.x of this module "gzreadline"
	    ignores the $/ variable - it always uses the string "\n" as the line delimiter.

	    If you want to read a gzip file a line at a time and have it respect the $/ variable
	    (or $INPUT_RECORD_SEPARATOR, or $RS when "English" is in use) see
	    IO::Uncompress::Gunzip.

       $byteswritten = $gz->gzwrite($buffer) ;
	    Writes the contents of $buffer to the compressed file. Returns the number of bytes
	    actually written, or 0 on error.

       $status = $gz->gzflush($flush_type) ;
	    Flushes all pending output into the compressed file.

	    This method takes an optional parameter, $flush_type, that controls how the flushing
	    will be carried out. By default the $flush_type used is "Z_FINISH". Other valid
	    values for $flush_type are "Z_NO_FLUSH", "Z_SYNC_FLUSH", "Z_FULL_FLUSH" and
	    "Z_BLOCK". It is strongly recommended that you only set the "flush_type" parameter if
	    you fully understand the implications of what it does - overuse of "flush" can
	    seriously degrade the level of compression achieved. See the "zlib" documentation for
	    details.

	    Returns 0 on success.

       $offset = $gz->gztell() ;
	    Returns the uncompressed file offset.

       $status = $gz->gzseek($offset, $whence) ;
	    Provides a sub-set of the "seek" functionality, with the restriction that it is only
	    legal to seek forward in the compressed file.  It is a fatal error to attempt to seek
	    backward.

	    When opened for writing, empty parts of the file will have NULL (0x00) bytes written
	    to them.

	    The $whence parameter should be one of SEEK_SET, SEEK_CUR or SEEK_END.

	    Returns 1 on success, 0 on failure.

       $gz->gzclose
	    Closes the compressed file. Any pending data is flushed to the file before it is
	    closed.

	    Returns 0 on success.

       $gz->gzsetparams($level, $strategy
	    Change settings for the deflate stream $gz.

	    The list of the valid options is shown below. Options not specified will remain
	    unchanged.

	    Note: This method is only available if you are running zlib 1.0.6 or better.

	    $level
		 Defines the compression level. Valid values are 0 through 9, "Z_NO_COMPRESSION",
		 "Z_BEST_SPEED", "Z_BEST_COMPRESSION", and "Z_DEFAULT_COMPRESSION".

	    $strategy
		 Defines the strategy used to tune the compression. The valid values are
		 "Z_DEFAULT_STRATEGY", "Z_FILTERED" and "Z_HUFFMAN_ONLY".

       $gz->gzerror
	    Returns the zlib error message or number for the last operation associated with $gz.
	    The return value will be the zlib error number when used in a numeric context and the
	    zlib error message when used in a string context. The zlib error number constants,
	    shown below, are available for use.

		Z_OK
		Z_STREAM_END
		Z_ERRNO
		Z_STREAM_ERROR
		Z_DATA_ERROR
		Z_MEM_ERROR
		Z_BUF_ERROR

       $gzerrno
	    The $gzerrno scalar holds the error code associated with the most recent gzip
	    routine. Note that unlike "gzerror()", the error is not associated with a particular
	    file.

	    As with "gzerror()" it returns an error number in numeric context and an error
	    message in string context. Unlike "gzerror()" though, the error message will
	    correspond to the zlib message when the error is associated with zlib itself, or the
	    UNIX error message when it is not (i.e. zlib returned "Z_ERRORNO").

	    As there is an overlap between the error numbers used by zlib and UNIX, $gzerrno
	    should only be used to check for the presence of an error in numeric context. Use
	    "gzerror()" to check for specific zlib errors. The gzcat example below shows how the
	    variable can be used safely.

   Examples
       Here is an example script which uses the interface. It implements a gzcat function.

	   use strict ;
	   use warnings ;

	   use Compress::Zlib ;

	   # use stdin if no files supplied
	   @ARGV = '-' unless @ARGV ;

	   foreach my $file (@ARGV) {
	       my $buffer ;

	       my $gz = gzopen($file, "rb")
		    or die "Cannot open $file: $gzerrno\n" ;

	       print $buffer while $gz->gzread($buffer) > 0 ;

	       die "Error reading from $file: $gzerrno" . ($gzerrno+0) . "\n"
		   if $gzerrno != Z_STREAM_END ;

	       $gz->gzclose() ;
	   }

       Below is a script which makes use of "gzreadline". It implements a very simple grep like
       script.

	   use strict ;
	   use warnings ;

	   use Compress::Zlib ;

	   die "Usage: gzgrep pattern [file...]\n"
	       unless @ARGV >= 1;

	   my $pattern = shift ;

	   # use stdin if no files supplied
	   @ARGV = '-' unless @ARGV ;

	   foreach my $file (@ARGV) {
	       my $gz = gzopen($file, "rb")
		    or die "Cannot open $file: $gzerrno\n" ;

	       while ($gz->gzreadline($_) > 0) {
		   print if /$pattern/ ;
	       }

	       die "Error reading from $file: $gzerrno\n"
		   if $gzerrno != Z_STREAM_END ;

	       $gz->gzclose() ;
	   }

       This script, gzstream, does the opposite of the gzcat script above. It reads from standard
       input and writes a gzip data stream to standard output.

	   use strict ;
	   use warnings ;

	   use Compress::Zlib ;

	   binmode STDOUT;  # gzopen only sets it on the fd

	   my $gz = gzopen(\*STDOUT, "wb")
		 or die "Cannot open stdout: $gzerrno\n" ;

	   while (<>) {
	       $gz->gzwrite($_)
		 or die "error writing: $gzerrno\n" ;
	   }

	   $gz->gzclose ;

   Compress::Zlib::memGzip
       This function is used to create an in-memory gzip file with the minimum possible gzip
       header (exactly 10 bytes).

	   $dest = Compress::Zlib::memGzip($buffer)
	       or die "Cannot compress: $gzerrno\n";

       If successful, it returns the in-memory gzip file. Otherwise it returns "undef" and the
       $gzerrno variable will store the zlib error code.

       The $buffer parameter can either be a scalar or a scalar reference.

       See IO::Compress::Gzip for an alternative way to carry out in-memory gzip compression.

   Compress::Zlib::memGunzip
       This function is used to uncompress an in-memory gzip file.

	   $dest = Compress::Zlib::memGunzip($buffer)
	       or die "Cannot uncompress: $gzerrno\n";

       If successful, it returns the uncompressed gzip file. Otherwise it returns "undef" and the
       $gzerrno variable will store the zlib error code.

       The $buffer parameter can either be a scalar or a scalar reference. The contents of the
       $buffer parameter are destroyed after calling this function.

       If $buffer consists of multiple concatenated gzip data streams only the first will be
       uncompressed. Use "gunzip" with the "MultiStream" option in the "IO::Uncompress::Gunzip"
       module if you need to deal with concatenated data streams.

       See IO::Uncompress::Gunzip for an alternative way to carry out in-memory gzip
       uncompression.

COMPRESS/UNCOMPRESS
       Two functions are provided to perform in-memory compression/uncompression of RFC 1950 data
       streams. They are called "compress" and "uncompress".

       $dest = compress($source [, $level] ) ;
	    Compresses $source. If successful it returns the compressed data. Otherwise it
	    returns undef.

	    The source buffer, $source, can either be a scalar or a scalar reference.

	    The $level parameter defines the compression level. Valid values are 0 through 9,
	    "Z_NO_COMPRESSION", "Z_BEST_SPEED", "Z_BEST_COMPRESSION", and
	    "Z_DEFAULT_COMPRESSION".  If $level is not specified "Z_DEFAULT_COMPRESSION" will be
	    used.

       $dest = uncompress($source) ;
	    Uncompresses $source. If successful it returns the uncompressed data. Otherwise it
	    returns undef.

	    The source buffer can either be a scalar or a scalar reference.

       Please note: the two functions defined above are not compatible with the Unix commands of
       the same name.

       See IO::Deflate and IO::Inflate included with this distribution for an alternative
       interface for reading/writing RFC 1950 files/buffers.

Deflate Interface
       This section defines an interface that allows in-memory compression using the deflate
       interface provided by zlib.

       Here is a definition of the interface available:

   ($d, $status) = deflateInit( [OPT] )
       Initialises a deflation stream.

       It combines the features of the zlib functions "deflateInit", "deflateInit2" and
       "deflateSetDictionary".

       If successful, it will return the initialised deflation stream, $d and $status of "Z_OK"
       in a list context. In scalar context it returns the deflation stream, $d, only.

       If not successful, the returned deflation stream ($d) will be undef and $status will hold
       the exact zlib error code.

       The function optionally takes a number of named options specified as "-Name=>value" pairs.
       This allows individual options to be tailored without having to specify them all in the
       parameter list.

       For backward compatibility, it is also possible to pass the parameters as a reference to a
       hash containing the name=>value pairs.

       The function takes one optional parameter, a reference to a hash.  The contents of the
       hash allow the deflation interface to be tailored.

       Here is a list of the valid options:

       -Level
	    Defines the compression level. Valid values are 0 through 9, "Z_NO_COMPRESSION",
	    "Z_BEST_SPEED", "Z_BEST_COMPRESSION", and "Z_DEFAULT_COMPRESSION".

	    The default is Z_DEFAULT_COMPRESSION.

       -Method
	    Defines the compression method. The only valid value at present (and the default) is
	    Z_DEFLATED.

       -WindowBits
	    To create an RFC 1950 data stream, set "WindowBits" to a positive number.

	    To create an RFC 1951 data stream, set "WindowBits" to "-MAX_WBITS".

	    For a full definition of the meaning and valid values for "WindowBits" refer to the
	    zlib documentation for deflateInit2.

	    Defaults to MAX_WBITS.

       -MemLevel
	    For a definition of the meaning and valid values for "MemLevel" refer to the zlib
	    documentation for deflateInit2.

	    Defaults to MAX_MEM_LEVEL.

       -Strategy
	    Defines the strategy used to tune the compression. The valid values are
	    "Z_DEFAULT_STRATEGY", "Z_FILTERED" and "Z_HUFFMAN_ONLY".

	    The default is Z_DEFAULT_STRATEGY.

       -Dictionary
	    When a dictionary is specified Compress::Zlib will automatically call
	    "deflateSetDictionary" directly after calling "deflateInit". The Adler32 value for
	    the dictionary can be obtained by calling the method "$d-"dict_adler()>.

	    The default is no dictionary.

       -Bufsize
	    Sets the initial size for the deflation buffer. If the buffer has to be reallocated
	    to increase the size, it will grow in increments of "Bufsize".

	    The default is 4096.

       Here is an example of using the "deflateInit" optional parameter list to override the
       default buffer size and compression level. All other options will take their default
       values.

	   deflateInit( -Bufsize => 300,
			-Level => Z_BEST_SPEED	) ;

   ($out, $status) = $d->deflate($buffer)
       Deflates the contents of $buffer. The buffer can either be a scalar or a scalar reference.
       When finished, $buffer will be completely processed (assuming there were no errors). If
       the deflation was successful it returns the deflated output, $out, and a status value,
       $status, of "Z_OK".

       On error, $out will be undef and $status will contain the zlib error code.

       In a scalar context "deflate" will return $out only.

       As with the deflate function in zlib, it is not necessarily the case that any output will
       be produced by this method. So don't rely on the fact that $out is empty for an error
       test.

   ($out, $status) = $d->flush() =head2 ($out, $status) = $d->flush($flush_type)
       Typically used to finish the deflation. Any pending output will be returned via $out.
       $status will have a value "Z_OK" if successful.

       In a scalar context "flush" will return $out only.

       Note that flushing can seriously degrade the compression ratio, so it should only be used
       to terminate a decompression (using "Z_FINISH") or when you want to create a full flush
       point (using "Z_FULL_FLUSH").

       By default the "flush_type" used is "Z_FINISH". Other valid values for "flush_type" are
       "Z_NO_FLUSH", "Z_PARTIAL_FLUSH", "Z_SYNC_FLUSH" and "Z_FULL_FLUSH". It is strongly
       recommended that you only set the "flush_type" parameter if you fully understand the
       implications of what it does. See the "zlib" documentation for details.

   $status = $d->deflateParams([OPT])
       Change settings for the deflate stream $d.

       The list of the valid options is shown below. Options not specified will remain unchanged.

       -Level
	    Defines the compression level. Valid values are 0 through 9, "Z_NO_COMPRESSION",
	    "Z_BEST_SPEED", "Z_BEST_COMPRESSION", and "Z_DEFAULT_COMPRESSION".

       -Strategy
	    Defines the strategy used to tune the compression. The valid values are
	    "Z_DEFAULT_STRATEGY", "Z_FILTERED" and "Z_HUFFMAN_ONLY".

   $d->dict_adler()
       Returns the adler32 value for the dictionary.

   $d->msg()
       Returns the last error message generated by zlib.

   $d->total_in()
       Returns the total number of bytes uncompressed bytes input to deflate.

   $d->total_out()
       Returns the total number of compressed bytes output from deflate.

   Example
       Here is a trivial example of using "deflate". It simply reads standard input, deflates it
       and writes it to standard output.

	   use strict ;
	   use warnings ;

	   use Compress::Zlib ;

	   binmode STDIN;
	   binmode STDOUT;
	   my $x = deflateInit()
	      or die "Cannot create a deflation stream\n" ;

	   my ($output, $status) ;
	   while (<>)
	   {
	       ($output, $status) = $x->deflate($_) ;

	       $status == Z_OK
		   or die "deflation failed\n" ;

	       print $output ;
	   }

	   ($output, $status) = $x->flush() ;

	   $status == Z_OK
	       or die "deflation failed\n" ;

	   print $output ;

Inflate Interface
       This section defines the interface available that allows in-memory uncompression using the
       deflate interface provided by zlib.

       Here is a definition of the interface:

   ($i, $status) = inflateInit()
       Initialises an inflation stream.

       In a list context it returns the inflation stream, $i, and the zlib status code in
       $status. In a scalar context it returns the inflation stream only.

       If successful, $i will hold the inflation stream and $status will be "Z_OK".

       If not successful, $i will be undef and $status will hold the zlib error code.

       The function optionally takes a number of named options specified as "-Name=>value" pairs.
       This allows individual options to be tailored without having to specify them all in the
       parameter list.

       For backward compatibility, it is also possible to pass the parameters as a reference to a
       hash containing the name=>value pairs.

       The function takes one optional parameter, a reference to a hash.  The contents of the
       hash allow the deflation interface to be tailored.

       Here is a list of the valid options:

       -WindowBits
	    To uncompress an RFC 1950 data stream, set "WindowBits" to a positive number.

	    To uncompress an RFC 1951 data stream, set "WindowBits" to "-MAX_WBITS".

	    For a full definition of the meaning and valid values for "WindowBits" refer to the
	    zlib documentation for inflateInit2.

	    Defaults to MAX_WBITS.

       -Bufsize
	    Sets the initial size for the inflation buffer. If the buffer has to be reallocated
	    to increase the size, it will grow in increments of "Bufsize".

	    Default is 4096.

       -Dictionary
	    The default is no dictionary.

       Here is an example of using the "inflateInit" optional parameter to override the default
       buffer size.

	   inflateInit( -Bufsize => 300 ) ;

   ($out, $status) = $i->inflate($buffer)
       Inflates the complete contents of $buffer. The buffer can either be a scalar or a scalar
       reference.

       Returns "Z_OK" if successful and "Z_STREAM_END" if the end of the compressed data has been
       successfully reached.  If not successful, $out will be undef and $status will hold the
       zlib error code.

       The $buffer parameter is modified by "inflate". On completion it will contain what remains
       of the input buffer after inflation. This means that $buffer will be an empty string when
       the return status is "Z_OK". When the return status is "Z_STREAM_END" the $buffer
       parameter will contains what (if anything) was stored in the input buffer after the
       deflated data stream.

       This feature is useful when processing a file format that encapsulates a  compressed data
       stream (e.g. gzip, zip).

   $status = $i->inflateSync($buffer)
       Scans $buffer until it reaches either a full flush point or the end of the buffer.

       If a full flush point is found, "Z_OK" is returned and $buffer will be have all data up to
       the flush point removed. This can then be passed to the "deflate" method.

       Any other return code means that a flush point was not found. If more data is available,
       "inflateSync" can be called repeatedly with more compressed data until the flush point is
       found.

   $i->dict_adler()
       Returns the adler32 value for the dictionary.

   $i->msg()
       Returns the last error message generated by zlib.

   $i->total_in()
       Returns the total number of bytes compressed bytes input to inflate.

   $i->total_out()
       Returns the total number of uncompressed bytes output from inflate.

   Example
       Here is an example of using "inflate".

	   use strict ;
	   use warnings ;

	   use Compress::Zlib ;

	   my $x = inflateInit()
	      or die "Cannot create a inflation stream\n" ;

	   my $input = '' ;
	   binmode STDIN;
	   binmode STDOUT;

	   my ($output, $status) ;
	   while (read(STDIN, $input, 4096))
	   {
	       ($output, $status) = $x->inflate(\$input) ;

	       print $output
		   if $status == Z_OK or $status == Z_STREAM_END ;

	       last if $status != Z_OK ;
	   }

	   die "inflation failed\n"
	       unless $status == Z_STREAM_END ;

CHECKSUM FUNCTIONS
       Two functions are provided by zlib to calculate checksums. For the Perl interface, the
       order of the two parameters in both functions has been reversed. This allows both running
       checksums and one off calculations to be done.

	   $crc = adler32($buffer [,$crc]) ;
	   $crc = crc32($buffer [,$crc]) ;

       The buffer parameters can either be a scalar or a scalar reference.

       If the $crc parameters is "undef", the crc value will be reset.

       If you have built this module with zlib 1.2.3 or better, two more CRC-related functions
       are available.

	   $crc = adler32_combine($crc1, $crc2, $len2)l
	   $crc = crc32_combine($adler1, $adler2, $len2)

       These functions allow checksums to be merged.

Misc
   my $version = Compress::Zlib::zlib_version();
       Returns the version of the zlib library.

CONSTANTS
       All the zlib constants are automatically imported when you make use of Compress::Zlib.

SEE ALSO
       IO::Compress::Gzip, IO::Uncompress::Gunzip, IO::Compress::Deflate,
       IO::Uncompress::Inflate, IO::Compress::RawDeflate, IO::Uncompress::RawInflate,
       IO::Compress::Bzip2, IO::Uncompress::Bunzip2, IO::Compress::Lzma, IO::Uncompress::UnLzma,
       IO::Compress::Xz, IO::Uncompress::UnXz, IO::Compress::Lzop, IO::Uncompress::UnLzop,
       IO::Compress::Lzf, IO::Uncompress::UnLzf, IO::Uncompress::AnyInflate,
       IO::Uncompress::AnyUncompress

       IO::Compress::FAQ

       File::GlobMapper, Archive::Zip, Archive::Tar, IO::Zlib

       For RFC 1950, 1951 and 1952 see http://www.faqs.org/rfcs/rfc1950.html,
       http://www.faqs.org/rfcs/rfc1951.html and http://www.faqs.org/rfcs/rfc1952.html

       The zlib compression library was written by Jean-loup Gailly gzip@prep.ai.mit.edu and Mark
       Adler madler@alumni.caltech.edu.

       The primary site for the zlib compression library is http://www.zlib.org.

       The primary site for gzip is http://www.gzip.org.

AUTHOR
       This module was written by Paul Marquess, pmqs@cpan.org.

MODIFICATION HISTORY
       See the Changes file.

COPYRIGHT AND LICENSE
       Copyright (c) 1995-2013 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.

perl v5.16.3				    2013-05-19				Compress::Zlib(3)
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