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Compress::Raw::Bzip2(3)Perl Programmers	Reference GuideCompress::Raw::Bzip2(3)

NAME
       Compress::Raw::Bzip2 - Low-Level	Interface to bzip2 compression library

SYNOPSIS
	   use Compress::Raw::Bzip2 ;

	   my ($bz, $status) = new Compress::Raw::Bzip2	[OPTS]
	       or die "Cannot create bzip2 object: $bzerno\n";

	   $status = $bz->bzdeflate($input, $output);
	   $status = $bz->bzflush($output);
	   $status = $bz->bzclose($output);

	   my ($bz, $status) = new Compress::Raw::Bunzip2 [OPTS]
	       or die "Cannot create bunzip2 object: $bzerno\n";

	   $status = $bz->bzinflate($input, $output);

	   my $version = Compress::Raw::Bzip2::bzlibversion();

DESCRIPTION
       "Compress::Raw::Bzip2" provides an interface to the in-memory
       compression/uncompression functions from	the bzip2 compression library.

       Although	the primary purpose for	the existence of
       "Compress::Raw::Bzip2" is for use by the	 "IO::Compress::Bzip2" and
       "IO::Compress::Bunzip2" modules,	it can be used on its own for simple
       compression/uncompression tasks.

Compression
   ($z,	$status) = new Compress::Raw::Bzip2 $appendOutput, $blockSize100k,
       $workfactor;
       Creates a new compression object.

       If successful, it will return the initialised compression object, $z
       and a $status of	"BZ_OK"	in a list context. In scalar context it
       returns the deflation object, $z, only.

       If not successful, the returned compression object, $z, will be undef
       and $status will	hold the a bzip2 error code.

       Below is	a list of the valid options:

       $appendOutput
	    Controls whether the compressed data is appended to	the output
	    buffer in the "bzdeflate", "bzflush" and "bzclose" methods.

	    Defaults to	1.

       $blockSize100k
	    To quote the bzip2 documentation

		blockSize100k specifies	the block size to be used for compression. It
		should be a value between 1 and	9 inclusive, and the actual block size
		used is	100000 x this figure. 9	gives the best compression but takes
		most memory.

	    Defaults to	1.

       $workfactor
	    To quote the bzip2 documentation

		This parameter controls	how the	compression phase behaves when
		presented with worst case, highly repetitive, input data. If
		compression runs into difficulties caused by repetitive	data, the
		library	switches from the standard sorting algorithm to	a fallback
		algorithm. The fallback	is slower than the standard algorithm by
		perhaps	a factor of three, but always behaves reasonably, no matter how
		bad the	input.

		Lower values of	workFactor reduce the amount of	effort the standard
		algorithm will expend before resorting to the fallback.	You should set
		this parameter carefully; too low, and many inputs will	be handled by
		the fallback algorithm and so compress rather slowly, too high,	and
		your average-to-worst case compression times can become	very large. The
		default	value of 30 gives reasonable behaviour over a wide range of
		circumstances.

		Allowable values range from 0 to 250 inclusive.	0 is a special case,
		equivalent to using the	default	value of 30.

	    Defaults to	0.

   $status = $bz->bzdeflate($input, $output);
       Reads the contents of $input, compresses	it and writes the compressed
       data to $output.

       Returns "BZ_RUN_OK" on success and a "bzip2" error code on failure.

       If "appendOutput" is enabled in the constructor for the bzip2 object,
       the compressed data will	be appended to $output.	If not enabled,
       $output will be truncated before	the compressed data is written to it.

   $status = $bz->bzflush($output);
       Flushes any pending compressed data to $output.

       Returns "BZ_RUN_OK" on success and a "bzip2" error code on failure.

   $status = $bz->bzclose($output);
       Terminates the compressed data stream and flushes any pending
       compressed data to $output.

       Returns "BZ_STREAM_END" on success and a	"bzip2"	error code on failure.

   Example
Uncompression
   ($z,	$status) = new Compress::Raw::Bunzip2 $appendOutput, $consumeInput,
       $small, $verbosity, $limitOutput;
       If successful, it will return the initialised uncompression object, $z
       and a $status of	"BZ_OK"	in a list context. In scalar context it
       returns the deflation object, $z, only.

       If not successful, the returned uncompression object, $z, will be undef
       and $status will	hold the a bzip2 error code.

       Below is	a list of the valid options:

       $appendOutput
	    Controls whether the compressed data is appended to	the output
	    buffer in the "bzinflate", "bzflush" and "bzclose" methods.

	    Defaults to	1.

       $consumeInput
       $small
	    To quote the bzip2 documentation

		If small is nonzero, the library will use an alternative decompression
		algorithm which	uses less memory but at	the cost of decompressing more
		slowly (roughly	speaking, half the speed, but the maximum memory
		requirement drops to around 2300k).

	    Defaults to	0.

       $limitOutput
	    The	"LimitOutput" option changes the behavior of the
	    "$i->bzinflate" method so that the amount of memory	used by	the
	    output buffer can be limited.

	    When "LimitOutput" is used the size	of the output buffer used will
	    either be the 16k or the amount of memory already allocated	to
	    $output, whichever is larger. Predicting the output	size available
	    is tricky, so don't	rely on	getting	an exact output	buffer size.

	    When "LimitOutout" is not specified	"$i->bzinflate"	will use as
	    much memory	as it takes to write all the uncompressed data it
	    creates by uncompressing the input buffer.

	    If "LimitOutput" is	enabled, the "ConsumeInput" option will	also
	    be enabled.

	    This option	defaults to false.

       $verbosity
	    This parameter is ignored.

	    Defaults to	0.

   $status = $z->bzinflate($input, $output);
       Uncompresses $input and writes the uncompressed data to $output.

       Returns "BZ_OK" if the uncompression was	successful, but	the end	of the
       compressed data stream has not been reached. Returns "BZ_STREAM_END" on
       successful uncompression	and the	end of the compression stream has been
       reached.

       If "consumeInput" is enabled in the constructor for the bunzip2 object,
       $input will have	all compressed data removed from it after
       uncompression. On "BZ_OK" return	this will mean that $input will	be an
       empty string; when "BZ_STREAM_END" $input will either be	an empty
       string or will contain whatever data immediately	followed the
       compressed data stream.

       If "appendOutput" is enabled in the constructor for the bunzip2 object,
       the uncompressed	data will be appended to $output. If not enabled,
       $output will be truncated before	the uncompressed data is written to
       it.

Misc
   my $version = Compress::Raw::Bzip2::bzlibversion();
       Returns the version of the underlying bzip2 library.

Constants
       The following bzip2 constants are exported by this module

		       BZ_RUN
		       BZ_FLUSH
		       BZ_FINISH

		       BZ_OK
		       BZ_RUN_OK
		       BZ_FLUSH_OK
		       BZ_FINISH_OK
		       BZ_STREAM_END
		       BZ_SEQUENCE_ERROR
		       BZ_PARAM_ERROR
		       BZ_MEM_ERROR
		       BZ_DATA_ERROR
		       BZ_DATA_ERROR_MAGIC
		       BZ_IO_ERROR
		       BZ_UNEXPECTED_EOF
		       BZ_OUTBUFF_FULL
		       BZ_CONFIG_ERROR

SUPPORT
       General feedback/questions/bug reports should be	sent to
       <https://github.com/pmqs/Compress-Raw-Bzip2/issues> (preferred) or
       <https://rt.cpan.org/Public/Dist/Display.html?Name=Compress-Raw-Bzip2>.

SEE ALSO
       Compress::Zlib, 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::Lzip, IO::Uncompress::UnLzip, IO::Compress::Lzop,
       IO::Uncompress::UnLzop, IO::Compress::Lzf, IO::Uncompress::UnLzf,
       IO::Compress::Zstd, IO::Uncompress::UnZstd, IO::Uncompress::AnyInflate,
       IO::Uncompress::AnyUncompress

       IO::Compress::FAQ

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

       The primary site	for the	bzip2 program is
       <https://sourceware.org/bzip2/>.

       See the module Compress::Bzip2

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

MODIFICATION HISTORY
       See the Changes file.

COPYRIGHT AND LICENSE
       Copyright (c) 2005-2021 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 v5.35.11			  2022-03-27	       Compress::Raw::Bzip2(3)

NAME | SYNOPSIS | DESCRIPTION | Compression | Uncompression | Misc | Constants | SUPPORT | SEE ALSO | AUTHOR | MODIFICATION HISTORY | COPYRIGHT AND LICENSE

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