2 * SPDX-License-Identifier: BSD-2-Clause-FreeBSD
4 * Copyright (c) 2000-2008 Marc Alexander Lehmann <schmorp@schmorp.de>
6 * Redistribution and use in source and binary forms, with or without modifica-
7 * tion, are permitted provided that the following conditions are met:
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42 /***********************************************************************
44 ** lzf -- an extremely fast/free compression/decompression-method
45 ** http://liblzf.plan9.de/
47 ** This algorithm is believed to be patent-free.
49 ***********************************************************************/
51 #define LZF_VERSION 0x0105 /* 1.5, API version */
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
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
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.
71 * The buffers must not be overlapping.
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
79 lzf_compress (const void *const in_data, unsigned int in_len,
80 void *out_data, unsigned int out_len);
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.
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
92 * If an error in the compressed data is detected, a zero is returned and
93 * errno is set to EINVAL.
95 * This function is very fast, about as fast as a copying loop.
98 lzf_decompress (const void *const in_data, unsigned int in_len,
99 void *out_data, unsigned int out_len);
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).
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.
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.
130 # define ULTRA_FAST 0
134 * Unconditionally aligning does not cost very much, so do it if unsure
137 # if !(defined(__i386) || defined (__amd64))
138 # define STRICT_ALIGN 1
140 # define STRICT_ALIGN 0
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).
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.
159 # define AVOID_ERRNO 0
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.
167 #ifndef LZF_STATE_ARG
168 # define LZF_STATE_ARG 0
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.
180 # define CHECK_INPUT 1
183 /*****************************************************************************/
184 /* nothing should be changed below */
186 typedef unsigned char u8;
188 typedef const u8 *LZF_STATE[1 << (HLOG)];
191 /* for unaligned accesses we need a 16 bit datatype. */
193 # if USHRT_MAX == 65535
194 typedef unsigned short u16;
195 # elif UINT_MAX == 65535
196 typedef unsigned int u16;
199 # define STRICT_ALIGN 1
204 # if defined(VERY_FAST)