nuttx/include/lzf.h

/****************************************************************************
 * lzf -- an extremely fast/free compression/decompression-method
 * http://liblzf.plan9.de/
 *
 *   Copyright (c) 2000-2008 Marc Alexander Lehmann <schmorp@schmorp.de>
 *   This algorithm is believed to be patent-free.
 * 
 * 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.
 *
 ****************************************************************************/

#ifndef __INCLUDE_LZF_H
#define __INCLUDE_LZF_H 1

/****************************************************************************
 * Pre-processor Definitions
 ****************************************************************************/

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

/****************************************************************************
 * Public Types
 ****************************************************************************/

#if LZF_USE_OFFSETS
# define LZF_HSLOT_BIAS ((const uint8_t *)in_data)
  typedef unsigned int lzf_hslot_t;
#else
# define LZF_HSLOT_BIAS 0
  typedef const uint8_t *lzf_hslot_t;
#endif

typedef lzf_hslot_t lzf_state_t[1 << HLOG];

/****************************************************************************
 * Public Function Prototypes
 ****************************************************************************/

/* 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.
 */

unsigned int lzf_compress(FAR const void *const in_data,
                          unsigned int in_len, FAR void *out_data,
                          unsigned int out_len, lzf_state_t htab);

/* 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(FAR const void *const in_data,
                            unsigned int in_len, FAR void *out_data,
                            unsigned int out_len);

#endif /* __INCLUDE_LZF_H */