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lzma

Introduction

The lzma egg provides a simple wrapper around the C library lzmalib, which in turn provides access to the excellent Lempel-Ziv-Markov chain algorithm.

Two functions are provided, which simply compress or decompress a buffer represented as a Chicken blob object.

Examples

 
(use lzma)

(blob->string (decompress (compress (string->blob "Hello, World!"))))
 => "Hello, World!"

(blob-size (compress (string->blob "Hello, World!")))
 => 32

(blob-size (compress (string->blob "Hello, World! Hello, World! Hello, World!")))
 => 36

Library functions

[procedure] (compress BLOB) => BLOB

Given a blob, returns a blob that's hopefully smaller, and contains all the entropy of the original blob. Returns #f in the event of failure (typically, an out-of-memory condition).

[procedure] (decompress BLOB) => BLOB

Given a blob returned by compress, returns the original blob. Returns #f in the event of failure (typically, an out-of-memory condition or an invalid input).

Authors

Alaric B. Snell-Pym

License

 
 Copyright (c) 2003-2009, Warhead.org.uk Ltd
 All rights reserved.
 Redistribution and use in source and binary forms, with or without
 modification, are permitted provided that the following conditions
 are met:
 Redistributions of source code must retain the above copyright
 notice, this list of conditions and the following disclaimer.
 Redistributions in binary form must reproduce the above copyright
 notice, this list of conditions and the following disclaimer in the
 documentation and/or other materials provided with the distribution.
 Neither the names of Warhead.org.uk Ltd, Snell Systems, nor Kitten
 Technologies, nor the names of their contributors may be used to
 endorse or promote products derived from this software without
 specific prior written permission.
 THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
 "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
 LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
 FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
 COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
 INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
 BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
 LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
 CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
 ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
 POSSIBILITY OF SUCH DAMAGE.

Requirements

You'll need lzmalib installed. Source of this can be had from http://tokyocabinet.sourceforge.net/misc/lzmalib-0.0.1.tar.gz.

Version History