xref: /freebsd/sbin/hastd/lzf.h (revision 6829dae12bb055451fa467da4589c43bd03b1e64)
1 /*-
2  * SPDX-License-Identifier: BSD-2-Clause-FreeBSD
3  *
4  * Copyright (c) 2000-2008 Marc Alexander Lehmann <schmorp@schmorp.de>
5  *
6  * Redistribution and use in source and binary forms, with or without modifica-
7  * tion, are permitted provided that the following conditions are met:
8  *
9  *   1.  Redistributions of source code must retain the above copyright notice,
10  *       this list of conditions and the following disclaimer.
11  *
12  *   2.  Redistributions in binary form must reproduce the above copyright
13  *       notice, this list of conditions and the following disclaimer in the
14  *       documentation and/or other materials provided with the distribution.
15  *
16  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR IMPLIED
17  * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MER-
18  * CHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.  IN NO
19  * EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPE-
20  * CIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
21  * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS;
22  * OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
23  * WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTH-
24  * ERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
25  * OF THE POSSIBILITY OF SUCH DAMAGE.
26  *
27  * Alternatively, the contents of this file may be used under the terms of
28  * the GNU General Public License ("GPL") version 2 or any later version,
29  * in which case the provisions of the GPL are applicable instead of
30  * the above. If you wish to allow the use of your version of this file
31  * only under the terms of the GPL and not to allow others to use your
32  * version of this file under the BSD license, indicate your decision
33  * by deleting the provisions above and replace them with the notice
34  * and other provisions required by the GPL. If you do not delete the
35  * provisions above, a recipient may use your version of this file under
36  * either the BSD or the GPL.
37  */
38 
39 #ifndef LZF_H
40 #define LZF_H
41 
42 /***********************************************************************
43 **
44 **	lzf -- an extremely fast/free compression/decompression-method
45 **	http://liblzf.plan9.de/
46 **
47 **	This algorithm is believed to be patent-free.
48 **
49 ***********************************************************************/
50 
51 #define LZF_VERSION 0x0105 /* 1.5, API version */
52 
53 /*
54  * Compress in_len bytes stored at the memory block starting at
55  * in_data and write the result to out_data, up to a maximum length
56  * of out_len bytes.
57  *
58  * If the output buffer is not large enough or any error occurs return 0,
59  * otherwise return the number of bytes used, which might be considerably
60  * more than in_len (but less than 104% of the original size), so it
61  * makes sense to always use out_len == in_len - 1), to ensure _some_
62  * compression, and store the data uncompressed otherwise (with a flag, of
63  * course.
64  *
65  * lzf_compress might use different algorithms on different systems and
66  * even different runs, thus might result in different compressed strings
67  * depending on the phase of the moon or similar factors. However, all
68  * these strings are architecture-independent and will result in the
69  * original data when decompressed using lzf_decompress.
70  *
71  * The buffers must not be overlapping.
72  *
73  * If the option LZF_STATE_ARG is enabled, an extra argument must be
74  * supplied which is not reflected in this header file. Refer to lzfP.h
75  * and lzf_c.c.
76  *
77  */
78 unsigned int
79 lzf_compress (const void *const in_data,  unsigned int in_len,
80               void             *out_data, unsigned int out_len);
81 
82 /*
83  * Decompress data compressed with some version of the lzf_compress
84  * function and stored at location in_data and length in_len. The result
85  * will be stored at out_data up to a maximum of out_len characters.
86  *
87  * If the output buffer is not large enough to hold the decompressed
88  * data, a 0 is returned and errno is set to E2BIG. Otherwise the number
89  * of decompressed bytes (i.e. the original length of the data) is
90  * returned.
91  *
92  * If an error in the compressed data is detected, a zero is returned and
93  * errno is set to EINVAL.
94  *
95  * This function is very fast, about as fast as a copying loop.
96  */
97 unsigned int
98 lzf_decompress (const void *const in_data,  unsigned int in_len,
99                 void             *out_data, unsigned int out_len);
100 
101 /*
102  * Size of hashtable is (1 << HLOG) * sizeof (char *)
103  * decompression is independent of the hash table size
104  * the difference between 15 and 14 is very small
105  * for small blocks (and 14 is usually a bit faster).
106  * For a low-memory/faster configuration, use HLOG == 13;
107  * For best compression, use 15 or 16 (or more, up to 23).
108  */
109 #ifndef HLOG
110 # define HLOG 16
111 #endif
112 
113 /*
114  * Sacrifice very little compression quality in favour of compression speed.
115  * This gives almost the same compression as the default code, and is
116  * (very roughly) 15% faster. This is the preferred mode of operation.
117  */
118 #ifndef VERY_FAST
119 # define VERY_FAST 1
120 #endif
121 
122 /*
123  * Sacrifice some more compression quality in favour of compression speed.
124  * (roughly 1-2% worse compression for large blocks and
125  * 9-10% for small, redundant, blocks and >>20% better speed in both cases)
126  * In short: when in need for speed, enable this for binary data,
127  * possibly disable this for text data.
128  */
129 #ifndef ULTRA_FAST
130 # define ULTRA_FAST 0
131 #endif
132 
133 /*
134  * Unconditionally aligning does not cost very much, so do it if unsure
135  */
136 #ifndef STRICT_ALIGN
137 # if !(defined(__i386) || defined (__amd64))
138 #  define STRICT_ALIGN 1
139 # else
140 #  define STRICT_ALIGN 0
141 # endif
142 #endif
143 
144 /*
145  * You may choose to pre-set the hash table (might be faster on some
146  * modern cpus and large (>>64k) blocks, and also makes compression
147  * deterministic/repeatable when the configuration otherwise is the same).
148  */
149 #ifndef INIT_HTAB
150 # define INIT_HTAB 1
151 #endif
152 
153 /*
154  * Avoid assigning values to errno variable? for some embedding purposes
155  * (linux kernel for example), this is necessary. NOTE: this breaks
156  * the documentation in lzf.h.
157  */
158 #ifndef AVOID_ERRNO
159 # define AVOID_ERRNO 0
160 #endif
161 
162 /*
163  * Wether to pass the LZF_STATE variable as argument, or allocate it
164  * on the stack. For small-stack environments, define this to 1.
165  * NOTE: this breaks the prototype in lzf.h.
166  */
167 #ifndef LZF_STATE_ARG
168 # define LZF_STATE_ARG 0
169 #endif
170 
171 /*
172  * Wether to add extra checks for input validity in lzf_decompress
173  * and return EINVAL if the input stream has been corrupted. This
174  * only shields against overflowing the input buffer and will not
175  * detect most corrupted streams.
176  * This check is not normally noticeable on modern hardware
177  * (<1% slowdown), but might slow down older cpus considerably.
178  */
179 #ifndef CHECK_INPUT
180 # define CHECK_INPUT 1
181 #endif
182 
183 /*****************************************************************************/
184 /* nothing should be changed below */
185 
186 typedef unsigned char u8;
187 
188 typedef const u8 *LZF_STATE[1 << (HLOG)];
189 
190 #if !STRICT_ALIGN
191 /* for unaligned accesses we need a 16 bit datatype. */
192 # include <limits.h>
193 # if USHRT_MAX == 65535
194     typedef unsigned short u16;
195 # elif UINT_MAX == 65535
196     typedef unsigned int u16;
197 # else
198 #  undef STRICT_ALIGN
199 #  define STRICT_ALIGN 1
200 # endif
201 #endif
202 
203 #if ULTRA_FAST
204 # if defined(VERY_FAST)
205 #  undef VERY_FAST
206 # endif
207 #endif
208 
209 #if INIT_HTAB
210 # ifdef __cplusplus
211 #  include <cstring>
212 # else
213 #  include <string.h>
214 # endif
215 #endif
216 
217 #endif
218