mfbt/lz4.h

   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