Nicholas Clark

NAME

Compress::Zlib::Perl - (Partial) Pure perl implementation of Compress::Zlib

SYNOPSIS

    use Compress::Zlib::Perl;
    ($i, $status) = inflateInit(-WindowBits => -MAX_WBITS);
    ($out, $status) = $i->inflate($buffer);

DESCRIPTION

This a pure perl implementation of Compress::Zlib's inflate API.

Inflating deflated data

Currently the only thing Compress::Zlib::Perl can do is inflate compressed data. A constructor and 3 methods from Compress::Zlib's interface are replicated:

inflateInit -WindowBits => -MAX_WBITS

Argument list specifies options. Expects that the option -WindowBits is set to a negative value. In scalar context returns an inflater object; in list context returns this object and a status (usually Z_OK)

inflate INPUT

Inflates this section of deflate compressed data stream. In scalar context returns some inflated data; in list context returns this data and an output status. The status is Z_OK if the input stream is not yet finished, Z_STREAM_END if all the input data is consumed and this output is the final output.

inflate modifies the input parameter; at the end of the compressed stream any data beyond its end remains in INPUT. Before the end of stream all input data is consumed during the inflate call.

This implementation of inflate may not be as prompt at returning data as Compress::Zlib's; this implementation currently buffers the last 32768 bytes of output data until the end of the input stream, rather than attempting to return as much data as possible during inflation.

total_in

Returns the total input (compressed) data so far

total_out

Returns the total output (uncompressed) data so far

EXPORT

crc32 BUFFER[, CRC32]

Calculate and return a 32 bit checksum for buffer. CRC32 is suitably initialised if undef is passed in.

Z_OK

Constant for returning normal status

Z_STREAM_END

Constant for returning end of stream

MAX_WBITS

Constant to pass to inflateInit (for compatibility with Compress::Zlib)

TODO

  • Test and if necessary fix on big endian systems

  • Backport to at least 5.005_03

  • Fill in all the other missing Comress::Zlib APIs

BUGS

  • Doesn't implement all of Compress::Zlib

  • Doesn't emulate Compress::Zlib's error return values - instead uses die

  • Slow. Well, what did you expect?

SEE ALSO

Compress::Zlib

AUTHOR

Ton Hospel wrote a pure perl gunzip program. Nicholas Clark, <nick@talking.bollo.cx<gt> turned it into a state machine and reworked the decompression core to fit Compress::Zlib's interface.

COPYRIGHT AND LICENSE

Copyright 2004 by Ton Hospel, Nicholas Clark

This library is free software; you can redistribute it and/or modify it under the same terms as Perl itself.