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Last change: 2008-08-25

LibLZF

=======================================================

Description

LibLZF is a very small data compression library. It consists of only two .c and two .h files and is very easy to incorporate into your own programs. The compression algorithm is very, very fast, yet still written in portable C.

Last not least, it is freely usable, unlike most other compression libraries which are under the GPL, this library uses a BSD-type license, so you can include it in your programs without worrying.

Features

Applications

LibLZF is an ideal library for the following applications:

Availablility

See the Schmorpforge Page for CVS and release info.

Releases: http://dist.schmorp.de/liblzf/

Changes

3.4  Tue Sep  2 06:45:00 CEST 2008
	- the fix from 3.3 introduced a compression bug, which is fixed in
          this release (which explains the mysterious prerelease...). Thanks
          once more to Clément Calmels.

3.3  Mon Aug 25 03:17:42 CEST 2008
	- lzf_compress could access memory after the given input buffer
          when outputting back references. reported with nice testcase
          by Clément Calmels.

3.2  Fri May  9 18:52:23 CEST 2008
	- include a workaround for failing POSIX and real-world compliance
          on 64 bit windows (microsoft claims to support POSIX, but is far
          from it). (bug found and analysed nicely by John Lilley).

3.1  Fri Nov 30 11:33:04 CET 2007
	- IMPORTANT BUGFIX: a too long final literal run would corrupt data
          in the encoder (this was introduced in 3.0 only, earlier versions
          are safe).

3.0  Tue Nov 13 22:13:09 CET 2007
	- switched to 2-clause bsd with "GPL v2 or any later version" option.
        - speed up compression by ~10-15% in common cases
          by some manual unrolling.
        - import some compiler tricks from JSON::XS, for further speed-ups.
        - tune hash functions depending on ULTRA_FAST or VERY_FAST settings.
        - for typical binary data (e.g. /bin/bash, memory dumps,
          canterbury corpus etc.), speed is now comparable to fastlz, but
          with better compression ratio. with ULTRA_FAST, it's typically
          3-15% faster than fastlz while still maintaining a similar ratio.
          (amd64 and core 2 duo, ymmv). thanks a lot for the competition :)
        - undo inline assembly in compressor, it is no longer helpful.
        - no changes to the decompressor.
        - use a HLOG of 16 by default now (formerly 15).

2.1  Fri Nov  2 13:34:42 CET 2007
	- switched to a 2-clause bsd license with GPL exception.
	- get rid of memcpy.
        - tentatively use rep movsb on x86 and x86_64 (gcc only) for a
          moderate speed improvement.
        - applied patch by Kein-Hong Man to maske lzf.c compile under
          the crippled mingw32 environment.

2.0  Fri Feb 16 23:11:18 CET 2007
	- replaced lzf demo by industrial-strength lzf utility with behaviour
          similar other compression utilities. Thanks for Stefan Traby for
          rewriting it!
        - fix state arg prototype.

1.7  Wed Sep 27 17:29:15 CEST 2006
	- remove bogus "unlzf" patch.
          note to self: never accept well-meant patches.
	- make lzf more robust in presence of padding bytes or sudden eof.

1.6  Fri Jul  7 17:31:26 CEST 2006
	- the lzf example utility will now uncompress if invoked
          as "unlzf" (patch by Scott Feeney).
        - add CHECK_INPUT option that adds more checks for input
          data validity.
        - help applications that do not pass in the correct length
          (such as php) by returning either EINVAL or E2BIG.
        - default HLOG size is now 15 (cpu caches have increased).
        - documentation fixes.

1.51 Thu Apr 14 22:15:46 CEST 2005
	- incorporated C♯ implementation of both the en- and decoder,
          written by "Oren J. Maurice".
          You can find it in the cs/ subdirectory.
        - make FRST, NEXT IDX overridable if lzf_c.c is directly included
          in the code.

1.5  Tue Mar  8 20:23:23 CET 2005
	- incorporated improvements by Adam D. Moss,
          which includes a new VERY_FAST mode which is
          a bit slower than ULTRA_FAST but much better,
          and enabled it as default.

1.401 Thu Mar  3 18:00:52 CET 2005
	- use cstring in c++, not string.h.
        - change of contact address.

1.4  Wed Dec 15 08:08:49 CET 2004
	- very very slight tuning of the hashing function.

1.3  Thu Mar 25 15:41:17 CET 2004
	- changed license of lzf core code to explicitly allow
          relicensing under the GPLv2.
	- added VPATH support as suggested by Björn Eriksson.

1.2  Mon Dec 29 13:47:28 CET 2003
	- avoid spurious memory accesses after the to-be-compressed
          memory region. originally reported by Michal Zalewski.
        - flip LZF_STACK_ARG meaning (to be correct).

1.1  Tue Dec 23 05:48:32 CET 2003
	- removed #warn directive, it's not worth the hassle.
        - add LZF_STACK_ARG and AVOID_ERRNO configurations
          for embedded systems.
        - make it compile cleanly as c++.
        - some small documentation and code fixes.

1.0  Sun Nov 17 12:37:37 CET 2002
	- slightly better compression ratio, almost unmeasurably
          slower.
        - some documentation fixes.

0.4  Thu Jun 13 14:11:10 CEST 2002
	- typoe fix.
        - lzf demo program now properly decompresses small files.
        - fix another 64 bit issue, found by Laurent Deniel.

0.3  Tue Jan 16 13:21:14 CET 2001
	- fix silly beginners 32/64 bit mistake.

0.2  Thu Jan  4 05:56:42 CET 2001
	- now totally independent of autoconfig, for
          easy inclusion into other programs.
        - much better fine-tuning, faster and better than 0.1.

0.1  2000
	- initial release.

lzf.h

/*
 * Copyright (c) 2000-2008 Marc Alexander Lehmann <schmorp@schmorp.de>
 * 
 * Redistribution and use in source and binary forms, with or without modifica-
 * tion, are permitted provided that the following conditions are met:
 * 
 *   1.  Redistributions of source code must retain the above copyright notice,
 *       this list of conditions and the following disclaimer.
 * 
 *   2.  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.
 * 
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR IMPLIED
 * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MER-
 * CHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.  IN NO
 * EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPE-
 * CIAL, 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 OTH-
 * ERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
 * OF THE POSSIBILITY OF SUCH DAMAGE.
 *
 * Alternatively, the contents of this file may be used under the terms of
 * the GNU General Public License ("GPL") version 2 or any later version,
 * in which case the provisions of the GPL are applicable instead of
 * the above. If you wish to allow the use of your version of this file
 * only under the terms of the GPL and not to allow others to use your
 * version of this file under the BSD license, indicate your decision
 * by deleting the provisions above and replace them with the notice
 * and other provisions required by the GPL. If you do not delete the
 * provisions above, a recipient may use your version of this file under
 * either the BSD or the GPL.
 */

#ifndef LZF_H
#define LZF_H

/***********************************************************************
**
**	lzf -- an extremely fast/free compression/decompression-method
**	http://liblzf.plan9.de/
**
**	This algorithm is believed to be patent-free.
**
***********************************************************************/

#define LZF_VERSION 0x0105 /* 1.5, API version */

/*
 * Compress in_len bytes stored at the memory block starting at
 * in_data and write the result to out_data, up to a maximum length
 * of out_len bytes.
 *
 * If the output buffer is not large enough or any error occurs return 0,
 * otherwise return the number of bytes used, which might be considerably
 * more than in_len (but less than 104% of the original size), so it
 * makes sense to always use out_len == in_len - 1), to ensure _some_
 * compression, and store the data uncompressed otherwise (with a flag, of
 * course.
 *
 * lzf_compress might use different algorithms on different systems and
 * even different runs, thus might result in different compressed strings
 * depending on the phase of the moon or similar factors. However, all
 * these strings are architecture-independent and will result in the
 * original data when decompressed using lzf_decompress.
 *
 * The buffers must not be overlapping.
 *
 * If the option LZF_STATE_ARG is enabled, an extra argument must be
 * supplied which is not reflected in this header file. Refer to lzfP.h
 * and lzf_c.c.
 *
 */
unsigned int 
lzf_compress (const void *const in_data,  unsigned int in_len,
              void             *out_data, unsigned int out_len);

/*
 * Decompress data compressed with some version of the lzf_compress
 * function and stored at location in_data and length in_len. The result
 * will be stored at out_data up to a maximum of out_len characters.
 *
 * If the output buffer is not large enough to hold the decompressed
 * data, a 0 is returned and errno is set to E2BIG. Otherwise the number
 * of decompressed bytes (i.e. the original length of the data) is
 * returned.
 *
 * If an error in the compressed data is detected, a zero is returned and
 * errno is set to EINVAL.
 *
 * This function is very fast, about as fast as a copying loop.
 */
unsigned int 
lzf_decompress (const void *const in_data,  unsigned int in_len,
                void             *out_data, unsigned int out_len);

#endif

lzfP.h

/*
 * Copyright (c) 2000-2007 Marc Alexander Lehmann <schmorp@schmorp.de>
 * 
 * Redistribution and use in source and binary forms, with or without modifica-
 * tion, are permitted provided that the following conditions are met:
 * 
 *   1.  Redistributions of source code must retain the above copyright notice,
 *       this list of conditions and the following disclaimer.
 * 
 *   2.  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.
 * 
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR IMPLIED
 * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MER-
 * CHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.  IN NO
 * EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPE-
 * CIAL, 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 OTH-
 * ERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
 * OF THE POSSIBILITY OF SUCH DAMAGE.
 *
 * Alternatively, the contents of this file may be used under the terms of
 * the GNU General Public License ("GPL") version 2 or any later version,
 * in which case the provisions of the GPL are applicable instead of
 * the above. If you wish to allow the use of your version of this file
 * only under the terms of the GPL and not to allow others to use your
 * version of this file under the BSD license, indicate your decision
 * by deleting the provisions above and replace them with the notice
 * and other provisions required by the GPL. If you do not delete the
 * provisions above, a recipient may use your version of this file under
 * either the BSD or the GPL.
 */

#ifndef LZFP_h
#define LZFP_h

#define STANDALONE 1 /* at the moment, this is ok. */

#ifndef STANDALONE
# include "lzf.h"
#endif

/*
 * Size of hashtable is (1 << HLOG) * sizeof (char *)
 * decompression is independent of the hash table size
 * the difference between 15 and 14 is very small
 * for small blocks (and 14 is usually a bit faster).
 * For a low-memory/faster configuration, use HLOG == 13;
 * For best compression, use 15 or 16 (or more, up to 23).
 */
#ifndef HLOG
# define HLOG 16
#endif

/*
 * Sacrifice very little compression quality in favour of compression speed.
 * This gives almost the same compression as the default code, and is
 * (very roughly) 15% faster. This is the preferred mode of operation.
 */
#ifndef VERY_FAST
# define VERY_FAST 1
#endif

/*
 * Sacrifice some more compression quality in favour of compression speed.
 * (roughly 1-2% worse compression for large blocks and
 * 9-10% for small, redundant, blocks and >>20% better speed in both cases)
 * In short: when in need for speed, enable this for binary data,
 * possibly disable this for text data.
 */
#ifndef ULTRA_FAST
# define ULTRA_FAST 0
#endif

/*
 * Unconditionally aligning does not cost very much, so do it if unsure
 */
#ifndef STRICT_ALIGN
# define STRICT_ALIGN !(defined(__i386) || defined (__amd64))
#endif

/*
 * You may choose to pre-set the hash table (might be faster on some
 * modern cpus and large (>>64k) blocks, and also makes compression
 * deterministic/repeatable when the configuration otherwise is the same).
 */
#ifndef INIT_HTAB
# define INIT_HTAB 0
#endif

/*
 * Avoid assigning values to errno variable? for some embedding purposes
 * (linux kernel for example), this is neccessary. NOTE: this breaks
 * the documentation in lzf.h.
 */
#ifndef AVOID_ERRNO
# define AVOID_ERRNO 0
#endif

/*
 * Wether to pass the LZF_STATE variable as argument, or allocate it
 * on the stack. For small-stack environments, define this to 1.
 * NOTE: this breaks the prototype in lzf.h.
 */
#ifndef LZF_STATE_ARG
# define LZF_STATE_ARG 0
#endif

/*
 * Wether to add extra checks for input validity in lzf_decompress
 * and return EINVAL if the input stream has been corrupted. This
 * only shields against overflowing the input buffer and will not
 * detect most corrupted streams.
 * This check is not normally noticable on modern hardware
 * (<1% slowdown), but might slow down older cpus considerably.
 */
#ifndef CHECK_INPUT
# define CHECK_INPUT 1
#endif

/*****************************************************************************/
/* nothing should be changed below */

typedef unsigned char u8;

typedef const u8 *LZF_STATE[1 << (HLOG)];

#if !STRICT_ALIGN
/* for unaligned accesses we need a 16 bit datatype. */
# include <limits.h>
# if USHRT_MAX == 65535
    typedef unsigned short u16;
# elif UINT_MAX == 65535
    typedef unsigned int u16;
# else
#  undef STRICT_ALIGN
#  define STRICT_ALIGN 1
# endif
#endif

#if ULTRA_FAST
# if defined(VERY_FAST)
#  undef VERY_FAST
# endif
#endif

#if INIT_HTAB
# ifdef __cplusplus
#  include <cstring>
# else
#  include <string.h>
# endif
#endif

#endif

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