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comparison: mfbt/lz4.h

mfbt/lz4.h

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1 /*
2 LZ4 - Fast LZ compression algorithm
3 Header File
4 Copyright (C) 2011-2014, Yann Collet.
5 BSD 2-Clause License (http://www.opensource.org/licenses/bsd-license.php)
6
7 Redistribution and use in source and binary forms, with or without
8 modification, are permitted provided that the following conditions are
9 met:
10
11 * Redistributions of source code must retain the above copyright
12 notice, this list of conditions and the following disclaimer.
13 * Redistributions in binary form must reproduce the above
14 copyright notice, this list of conditions and the following disclaimer
15 in the documentation and/or other materials provided with the
16 distribution.
17
18 THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
19 "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
20 LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
21 A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
22 OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
23 SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
24 LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
25 DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
26 THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
27 (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
28 OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
29
30 You can contact the author at :
31 - LZ4 source repository : http://code.google.com/p/lz4/
32 - LZ4 public forum : https://groups.google.com/forum/#!forum/lz4c
33 */
34 #pragma once
35
36 #if defined (__cplusplus)
37 extern "C" {
38 #endif
39
40
41 /**************************************
42 Version
43 **************************************/
44 #define LZ4_VERSION_MAJOR 1 /* for major interface/format changes */
45 #define LZ4_VERSION_MINOR 2 /* for minor interface/format changes */
46 #define LZ4_VERSION_RELEASE 0 /* for tweaks, bug-fixes, or development */
47
48
49 /**************************************
50 Tuning parameter
51 **************************************/
52 /*
53 * LZ4_MEMORY_USAGE :
54 * Memory usage formula : N->2^N Bytes (examples : 10 -> 1KB; 12 -> 4KB ; 16 -> 64KB; 20 -> 1MB; etc.)
55 * Increasing memory usage improves compression ratio
56 * Reduced memory usage can improve speed, due to cache effect
57 * Default value is 14, for 16KB, which nicely fits into Intel x86 L1 cache
58 */
59 #define LZ4_MEMORY_USAGE 14
60
61
62 /**************************************
63 Simple Functions
64 **************************************/
65
66 int LZ4_compress (const char* source, char* dest, int inputSize);
67 int LZ4_decompress_safe (const char* source, char* dest, int compressedSize, int maxOutputSize);
68
69 /*
70 LZ4_compress() :
71 Compresses 'inputSize' bytes from 'source' into 'dest'.
72 Destination buffer must be already allocated,
73 and must be sized to handle worst cases situations (input data not compressible)
74 Worst case size evaluation is provided by function LZ4_compressBound()
75 inputSize : Max supported value is LZ4_MAX_INPUT_VALUE
76 return : the number of bytes written in buffer dest
77 or 0 if the compression fails
78
79 LZ4_decompress_safe() :
80 compressedSize : is obviously the source size
81 maxOutputSize : is the size of the destination buffer, which must be already allocated.
82 return : the number of bytes decoded in the destination buffer (necessarily <= maxOutputSize)
83 If the destination buffer is not large enough, decoding will stop and output an error code (<0).
84 If the source stream is detected malformed, the function will stop decoding and return a negative result.
85 This function is protected against buffer overflow exploits :
86 it never writes outside of output buffer, and never reads outside of input buffer.
87 Therefore, it is protected against malicious data packets.
88 */
89
90
91 /*
92 Note :
93 Should you prefer to explicitly allocate compression-table memory using your own allocation method,
94 use the streaming functions provided below, simply reset the memory area between each call to LZ4_compress_continue()
95 */
96
97
98 /**************************************
99 Advanced Functions
100 **************************************/
101 #define LZ4_MAX_INPUT_SIZE 0x7E000000 /* 2 113 929 216 bytes */
102 #define LZ4_COMPRESSBOUND(isize) ((unsigned int)(isize) > (unsigned int)LZ4_MAX_INPUT_SIZE ? 0 : (isize) + ((isize)/255) + 16)
103
104 /*
105 LZ4_compressBound() :
106 Provides the maximum size that LZ4 may output in a "worst case" scenario (input data not compressible)
107 primarily useful for memory allocation of output buffer.
108 macro is also provided when result needs to be evaluated at compilation (such as stack memory allocation).
109
110 isize : is the input size. Max supported value is LZ4_MAX_INPUT_SIZE
111 return : maximum output size in a "worst case" scenario
112 or 0, if input size is too large ( > LZ4_MAX_INPUT_SIZE)
113 */
114 int LZ4_compressBound(int isize);
115
116
117 /*
118 LZ4_compress_limitedOutput() :
119 Compress 'inputSize' bytes from 'source' into an output buffer 'dest' of maximum size 'maxOutputSize'.
120 If it cannot achieve it, compression will stop, and result of the function will be zero.
121 This function never writes outside of provided output buffer.
122
123 inputSize : Max supported value is LZ4_MAX_INPUT_VALUE
124 maxOutputSize : is the size of the destination buffer (which must be already allocated)
125 return : the number of bytes written in buffer 'dest'
126 or 0 if the compression fails
127 */
128 int LZ4_compress_limitedOutput (const char* source, char* dest, int inputSize, int maxOutputSize);
129
130
131 /*
132 LZ4_decompress_fast() :
133 originalSize : is the original and therefore uncompressed size
134 return : the number of bytes read from the source buffer (in other words, the compressed size)
135 If the source stream is malformed, the function will stop decoding and return a negative result.
136 Destination buffer must be already allocated. Its size must be a minimum of 'originalSize' bytes.
137 note : This function is a bit faster than LZ4_decompress_safe()
138 It provides fast decompression and fully respect memory boundaries for properly formed compressed data.
139 It does not provide full protection against intentionnally modified data stream.
140 Use this function in a trusted environment (data to decode comes from a trusted source).
141 */
142 int LZ4_decompress_fast (const char* source, char* dest, int originalSize);
143
144
145 /*
146 LZ4_decompress_safe_partial() :
147 This function decompress a compressed block of size 'compressedSize' at position 'source'
148 into output buffer 'dest' of size 'maxOutputSize'.
149 The function tries to stop decompressing operation as soon as 'targetOutputSize' has been reached,
150 reducing decompression time.
151 return : the number of bytes decoded in the destination buffer (necessarily <= maxOutputSize)
152 Note : this number can be < 'targetOutputSize' should the compressed block to decode be smaller.
153 Always control how many bytes were decoded.
154 If the source stream is detected malformed, the function will stop decoding and return a negative result.
155 This function never writes outside of output buffer, and never reads outside of input buffer. It is therefore protected against malicious data packets
156 */
157 int LZ4_decompress_safe_partial (const char* source, char* dest, int compressedSize, int targetOutputSize, int maxOutputSize);
158
159
160 /***********************************************
161 Experimental Streaming Compression Functions
162 ***********************************************/
163
164 #define LZ4_STREAMSIZE_U32 ((1 << (LZ4_MEMORY_USAGE-2)) + 8)
165 #define LZ4_STREAMSIZE (LZ4_STREAMSIZE_U32 * sizeof(unsigned int))
166 /*
167 * LZ4_stream_t
168 * information structure to track an LZ4 stream.
169 * important : set this structure content to zero before first use !
170 */
171 typedef struct { unsigned int table[LZ4_STREAMSIZE_U32]; } LZ4_stream_t;
172
173 /*
174 * If you prefer dynamic allocation methods,
175 * LZ4_createStream
176 * provides a pointer (void*) towards an initialized LZ4_stream_t structure.
177 * LZ4_free just frees it.
178 */
179 void* LZ4_createStream();
180 int LZ4_free (void* LZ4_stream);
181
182
183 /*
184 * LZ4_loadDict
185 * Use this function to load a static dictionary into LZ4_stream.
186 * Any previous data will be forgotten, only 'dictionary' will remain in memory.
187 * Loading a size of 0 is allowed (same effect as init).
188 * Return : 1 if OK, 0 if error
189 */
190 int LZ4_loadDict (void* LZ4_stream, const char* dictionary, int dictSize);
191
192 /*
193 * LZ4_compress_continue
194 * Compress data block 'source', using blocks compressed before as dictionary to improve compression ratio
195 * Previous data blocks are assumed to still be present at their previous location.
196 */
197 int LZ4_compress_continue (void* LZ4_stream, const char* source, char* dest, int inputSize);
198
199 /*
200 * LZ4_compress_limitedOutput_continue
201 * Same as before, but also specify a maximum target compressed size (maxOutputSize)
202 * If objective cannot be met, compression exits, and returns a zero.
203 */
204 int LZ4_compress_limitedOutput_continue (void* LZ4_stream, const char* source, char* dest, int inputSize, int maxOutputSize);
205
206 /*
207 * LZ4_saveDict
208 * If previously compressed data block is not guaranteed to remain at its previous memory location
209 * save it into a safe place (char* safeBuffer)
210 * Note : you don't need to call LZ4_loadDict() afterwards,
211 * dictionary is immediately usable, you can therefore call again LZ4_compress_continue()
212 * Return : 1 if OK, 0 if error
213 * Note : any dictSize > 64 KB will be interpreted as 64KB.
214 */
215 int LZ4_saveDict (void* LZ4_stream, char* safeBuffer, int dictSize);
216
217
218 /************************************************
219 Experimental Streaming Decompression Functions
220 ************************************************/
221
222 #define LZ4_STREAMDECODESIZE_U32 4
223 #define LZ4_STREAMDECODESIZE (LZ4_STREAMDECODESIZE_U32 * sizeof(unsigned int))
224 /*
225 * LZ4_streamDecode_t
226 * information structure to track an LZ4 stream.
227 * important : set this structure content to zero before first use !
228 */
229 typedef struct { unsigned int table[LZ4_STREAMDECODESIZE_U32]; } LZ4_streamDecode_t;
230
231 /*
232 * If you prefer dynamic allocation methods,
233 * LZ4_createStreamDecode()
234 * provides a pointer (void*) towards an initialized LZ4_streamDecode_t structure.
235 * LZ4_free just frees it.
236 */
237 void* LZ4_createStreamDecode();
238 int LZ4_free (void* LZ4_stream); /* yes, it's the same one as for compression */
239
240 /*
241 *_continue() :
242 These decoding functions allow decompression of multiple blocks in "streaming" mode.
243 Previously decoded blocks must still be available at the memory position where they were decoded.
244 If it's not possible, save the relevant part of decoded data into a safe buffer,
245 and indicate where it stands using LZ4_setDictDecode()
246 */
247 int LZ4_decompress_safe_continue (void* LZ4_streamDecode, const char* source, char* dest, int compressedSize, int maxOutputSize);
248 int LZ4_decompress_fast_continue (void* LZ4_streamDecode, const char* source, char* dest, int originalSize);
249
250 /*
251 * LZ4_setDictDecode
252 * Use this function to instruct where to find the dictionary.
253 * This function can be used to specify a static dictionary,
254 * or to instruct where to find some previously decoded data saved into a different memory space.
255 * Setting a size of 0 is allowed (same effect as no dictionary).
256 * Return : 1 if OK, 0 if error
257 */
258 int LZ4_setDictDecode (void* LZ4_streamDecode, const char* dictionary, int dictSize);
259
260
261 /*
262 Advanced decoding functions :
263 *_usingDict() :
264 These decoding functions work the same as
265 a combination of LZ4_setDictDecode() followed by LZ4_decompress_x_continue()
266 all together into a single function call.
267 It doesn't use nor update an LZ4_streamDecode_t structure.
268 */
269 int LZ4_decompress_safe_usingDict (const char* source, char* dest, int compressedSize, int maxOutputSize, const char* dictStart, int dictSize);
270 int LZ4_decompress_fast_usingDict (const char* source, char* dest, int originalSize, const char* dictStart, int dictSize);
271
272
273
274 #if defined (__cplusplus)
275 }
276 #endif

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