2 * Copyright (c) 2000-2008 Marc Alexander Lehmann <schmorp@schmorp.de>
4 * Redistribution and use in source and binary forms, with or without modifica-
5 * tion, are permitted provided that the following conditions are met:
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40 /***********************************************************************
42 ** lzf -- an extremely fast/free compression/decompression-method
43 ** http://liblzf.plan9.de/
45 ** This algorithm is believed to be patent-free.
47 ***********************************************************************/
49 #define LZF_VERSION 0x0105 /* 1.5, API version */
52 * Compress in_len bytes stored at the memory block starting at
53 * in_data and write the result to out_data, up to a maximum length
56 * If the output buffer is not large enough or any error occurs return 0,
57 * otherwise return the number of bytes used, which might be considerably
58 * more than in_len (but less than 104% of the original size), so it
59 * makes sense to always use out_len == in_len - 1), to ensure _some_
60 * compression, and store the data uncompressed otherwise (with a flag, of
63 * lzf_compress might use different algorithms on different systems and
64 * even different runs, thus might result in different compressed strings
65 * depending on the phase of the moon or similar factors. However, all
66 * these strings are architecture-independent and will result in the
67 * original data when decompressed using lzf_decompress.
69 * The buffers must not be overlapping.
71 * If the option LZF_STATE_ARG is enabled, an extra argument must be
72 * supplied which is not reflected in this header file. Refer to lzfP.h
77 lzf_compress (const void *const in_data, unsigned int in_len,
78 void *out_data, unsigned int out_len);
81 * Decompress data compressed with some version of the lzf_compress
82 * function and stored at location in_data and length in_len. The result
83 * will be stored at out_data up to a maximum of out_len characters.
85 * If the output buffer is not large enough to hold the decompressed
86 * data, a 0 is returned and errno is set to E2BIG. Otherwise the number
87 * of decompressed bytes (i.e. the original length of the data) is
90 * If an error in the compressed data is detected, a zero is returned and
91 * errno is set to EINVAL.
93 * This function is very fast, about as fast as a copying loop.
96 lzf_decompress (const void *const in_data, unsigned int in_len,
97 void *out_data, unsigned int out_len);
100 * Size of hashtable is (1 << HLOG) * sizeof (char *)
101 * decompression is independent of the hash table size
102 * the difference between 15 and 14 is very small
103 * for small blocks (and 14 is usually a bit faster).
104 * For a low-memory/faster configuration, use HLOG == 13;
105 * For best compression, use 15 or 16 (or more, up to 23).
112 * Sacrifice very little compression quality in favour of compression speed.
113 * This gives almost the same compression as the default code, and is
114 * (very roughly) 15% faster. This is the preferred mode of operation.
121 * Sacrifice some more compression quality in favour of compression speed.
122 * (roughly 1-2% worse compression for large blocks and
123 * 9-10% for small, redundant, blocks and >>20% better speed in both cases)
124 * In short: when in need for speed, enable this for binary data,
125 * possibly disable this for text data.
128 # define ULTRA_FAST 0
132 * Unconditionally aligning does not cost very much, so do it if unsure
135 # define STRICT_ALIGN !(defined(__i386) || defined (__amd64))
139 * You may choose to pre-set the hash table (might be faster on some
140 * modern cpus and large (>>64k) blocks, and also makes compression
141 * deterministic/repeatable when the configuration otherwise is the same).
148 * Avoid assigning values to errno variable? for some embedding purposes
149 * (linux kernel for example), this is necessary. NOTE: this breaks
150 * the documentation in lzf.h.
153 # define AVOID_ERRNO 0
157 * Wether to pass the LZF_STATE variable as argument, or allocate it
158 * on the stack. For small-stack environments, define this to 1.
159 * NOTE: this breaks the prototype in lzf.h.
161 #ifndef LZF_STATE_ARG
162 # define LZF_STATE_ARG 0
166 * Wether to add extra checks for input validity in lzf_decompress
167 * and return EINVAL if the input stream has been corrupted. This
168 * only shields against overflowing the input buffer and will not
169 * detect most corrupted streams.
170 * This check is not normally noticeable on modern hardware
171 * (<1% slowdown), but might slow down older cpus considerably.
174 # define CHECK_INPUT 1
177 /*****************************************************************************/
178 /* nothing should be changed below */
180 typedef unsigned char u8;
182 typedef const u8 *LZF_STATE[1 << (HLOG)];
185 /* for unaligned accesses we need a 16 bit datatype. */
187 # if USHRT_MAX == 65535
188 typedef unsigned short u16;
189 # elif UINT_MAX == 65535
190 typedef unsigned int u16;
193 # define STRICT_ALIGN 1
198 # if defined(VERY_FAST)