| Compress::Raw::Bzip2 - Low-Level Interface to bzip2 compression library |
Compress::Raw::Bzip2 - Low-Level Interface to bzip2 compression library
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();
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.
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:
bzdeflate, bzflush and bzclose methods.
Defaults to 1.
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.
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.
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.
Flushes any pending compressed data to $output.
Returns BZ_RUN_OK on success and a bzip2 error code on failure.
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.
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:
bzinflate, bzflush and bzclose methods.
Defaults to 1.
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 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.
Defaults to 0.
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.
Returns the version of the underlying bzip2 library.
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
the Compress::Zlib manpage, the IO::Compress::Gzip manpage, the IO::Uncompress::Gunzip manpage, the IO::Compress::Deflate manpage, the IO::Uncompress::Inflate manpage, the IO::Compress::RawDeflate manpage, the IO::Uncompress::RawInflate manpage, the IO::Compress::Bzip2 manpage, the IO::Uncompress::Bunzip2 manpage, the IO::Compress::Lzma manpage, the IO::Uncompress::UnLzma manpage, the IO::Compress::Xz manpage, the IO::Uncompress::UnXz manpage, the IO::Compress::Lzip manpage, the IO::Uncompress::UnLzip manpage, the IO::Compress::Lzop manpage, the IO::Uncompress::UnLzop manpage, the IO::Compress::Lzf manpage, the IO::Uncompress::UnLzf manpage, the IO::Compress::Zstd manpage, the IO::Uncompress::UnZstd manpage, the IO::Uncompress::AnyInflate manpage, the IO::Uncompress::AnyUncompress manpage
File::GlobMapper, Archive::Zip, Archive::Tar, IO::Zlib
The primary site for the bzip2 program is http://www.bzip.org.
See the module Compress::Bzip2
This module was written by Paul Marquess, pmqs@cpan.org.
See the Changes file.
Copyright (c) 2005-2019 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.
| Compress::Raw::Bzip2 - Low-Level Interface to bzip2 compression library |