lzf.h

/*-
 * SPDX-License-Identifier: BSD-2-Clause
 *
 * Copyright (c) 2000-2008 Marc Alexander Lehmann <[email protected]>
 * 
 * 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);

/*
 * 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
# if !(defined(__i386) || defined (__amd64))
#  define STRICT_ALIGN 1
# else
#  define STRICT_ALIGN 0
# endif
#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 1
#endif

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

/*
 * Whether 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

/*
 * Whether 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 noticeable 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