ViewVC Help
View File | Revision Log | Show Annotations | Download File
/cvs/liblzf/lzf.h
Revision: 1.18
Committed: Mon Dec 10 21:34:33 2012 UTC (11 years, 7 months ago) by root
Content type: text/plain
Branch: MAIN
CVS Tags: HEAD
Changes since 1.17: +1 -1 lines
Log Message:
*** empty log message ***

File Contents

# Content
1 /*
2 * Copyright (c) 2000-2008 Marc Alexander Lehmann <schmorp@schmorp.de>
3 *
4 * Redistribution and use in source and binary forms, with or without modifica-
5 * tion, are permitted provided that the following conditions are met:
6 *
7 * 1. Redistributions of source code must retain the above copyright notice,
8 * this list of conditions and the following disclaimer.
9 *
10 * 2. Redistributions in binary form must reproduce the above copyright
11 * notice, this list of conditions and the following disclaimer in the
12 * documentation and/or other materials provided with the distribution.
13 *
14 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR IMPLIED
15 * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MER-
16 * CHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO
17 * EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPE-
18 * CIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
19 * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS;
20 * OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
21 * WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTH-
22 * ERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
23 * OF THE POSSIBILITY OF SUCH DAMAGE.
24 *
25 * Alternatively, the contents of this file may be used under the terms of
26 * the GNU General Public License ("GPL") version 2 or any later version,
27 * in which case the provisions of the GPL are applicable instead of
28 * the above. If you wish to allow the use of your version of this file
29 * only under the terms of the GPL and not to allow others to use your
30 * version of this file under the BSD license, indicate your decision
31 * by deleting the provisions above and replace them with the notice
32 * and other provisions required by the GPL. If you do not delete the
33 * provisions above, a recipient may use your version of this file under
34 * either the BSD or the GPL.
35 */
36
37 #ifndef LZF_H
38 #define LZF_H
39
40 /***********************************************************************
41 **
42 ** lzf -- an extremely fast/free compression/decompression-method
43 ** http://liblzf.plan9.de/
44 **
45 ** This algorithm is believed to be patent-free.
46 **
47 ***********************************************************************/
48
49 /* API version (major * 256 + minor)
50 * major API version gets bumped on incompatible changes.
51 * minor API version gets bumped on compatible changes.
52 * 1.5 => 1.6: add LZF_MAX_COMPRESSED_SIZE
53 */
54 #define LZF_VERSION 0x0106
55
56 /*
57 * Compress in_len bytes stored at the memory block starting at
58 * in_data and write the result to out_data, up to a maximum length
59 * of out_len bytes.
60 *
61 * If the output buffer is not large enough or any error occurs return 0,
62 * otherwise return the number of bytes used, which might be considerably
63 * more than in_len (but less than 1 + 104% of the original size), so it
64 * makes sense to always use out_len == in_len - 1), to ensure _some_
65 * compression, and store the data uncompressed otherwise (with a flag, of
66 * course.
67 *
68 * lzf_compress might use different algorithms on different systems and
69 * even different runs, thus might result in different compressed strings
70 * depending on the phase of the moon or similar factors. However, all
71 * these strings are architecture-independent and will result in the
72 * original data when decompressed using lzf_decompress.
73 *
74 * The buffers must not be overlapping.
75 *
76 * If the option LZF_STATE_ARG is enabled, an extra argument must be
77 * supplied which is not reflected in this header file. Refer to lzfP.h
78 * and lzf_c.c.
79 *
80 */
81 unsigned int
82 lzf_compress (const void *const in_data, unsigned int in_len,
83 void *out_data, unsigned int out_len);
84
85 /*
86 * The maximum out_len that needs to be allocated to make sure
87 * any input data can be compressed without overflowing the output
88 * buffer, i.e. maximum out_len = LZF_MAX_COMPRESSED_SIZE (in_len).
89 * This is useful if you don't want to bother with the case of
90 * incompressible data and just want to provide a buffer that is
91 * guaranteeed to be big enough.
92 * This macro can be used at preprocessing time.
93 */
94 #define LZF_MAX_COMPRESSED_SIZE(n) ((((n) * 33) >> 5 ) + 1)
95
96 /*
97 * Decompress data compressed with some version of the lzf_compress
98 * function and stored at location in_data and length in_len. The result
99 * will be stored at out_data up to a maximum of out_len characters.
100 *
101 * If the output buffer is not large enough to hold the decompressed
102 * data, a 0 is returned and errno is set to E2BIG. Otherwise the number
103 * of decompressed bytes (i.e. the original length of the data) is
104 * returned.
105 *
106 * If an error in the compressed data is detected, a zero is returned and
107 * errno is set to EINVAL.
108 *
109 * This function is very fast, about as fast as a copying loop.
110 */
111 unsigned int
112 lzf_decompress (const void *const in_data, unsigned int in_len,
113 void *out_data, unsigned int out_len);
114
115 #endif
116