1 /* Copyright 2013 Google Inc. All Rights Reserved. 2 3 Distributed under MIT license. 4 See file LICENSE for detail or copy at https://opensource.org/licenses/MIT 5 */ 6 7 /** 8 * @file 9 * API for Brotli compression. 10 */ 11 12 #ifndef BROTLI_ENC_ENCODE_H_ 13 #define BROTLI_ENC_ENCODE_H_ 14 15 #include <brotli/port.h> 16 #include <brotli/types.h> 17 18 #if defined(__cplusplus) || defined(c_plusplus) 19 extern "C" { 20 #endif 21 22 /** Minimal value for ::BROTLI_PARAM_LGWIN parameter. */ 23 #define BROTLI_MIN_WINDOW_BITS 10 24 /** 25 * Maximal value for ::BROTLI_PARAM_LGWIN parameter. 26 * 27 * @note equal to @c BROTLI_MAX_DISTANCE_BITS constant. 28 */ 29 #define BROTLI_MAX_WINDOW_BITS 24 30 /** 31 * Maximal value for ::BROTLI_PARAM_LGWIN parameter 32 * in "Large Window Brotli" (32-bit). 33 */ 34 #define BROTLI_LARGE_MAX_WINDOW_BITS 30 35 /** Minimal value for ::BROTLI_PARAM_LGBLOCK parameter. */ 36 #define BROTLI_MIN_INPUT_BLOCK_BITS 16 37 /** Maximal value for ::BROTLI_PARAM_LGBLOCK parameter. */ 38 #define BROTLI_MAX_INPUT_BLOCK_BITS 24 39 /** Minimal value for ::BROTLI_PARAM_QUALITY parameter. */ 40 #define BROTLI_MIN_QUALITY 0 41 /** Maximal value for ::BROTLI_PARAM_QUALITY parameter. */ 42 #define BROTLI_MAX_QUALITY 11 43 44 /** Options for ::BROTLI_PARAM_MODE parameter. */ 45 typedef enum BrotliEncoderMode { 46 /** 47 * Default compression mode. 48 * 49 * In this mode compressor does not know anything in advance about the 50 * properties of the input. 51 */ 52 BROTLI_MODE_GENERIC = 0, 53 /** Compression mode for UTF-8 formatted text input. */ 54 BROTLI_MODE_TEXT = 1, 55 /** Compression mode used in WOFF 2.0. */ 56 BROTLI_MODE_FONT = 2 57 } BrotliEncoderMode; 58 59 /** Default value for ::BROTLI_PARAM_QUALITY parameter. */ 60 #define BROTLI_DEFAULT_QUALITY 11 61 /** Default value for ::BROTLI_PARAM_LGWIN parameter. */ 62 #define BROTLI_DEFAULT_WINDOW 22 63 /** Default value for ::BROTLI_PARAM_MODE parameter. */ 64 #define BROTLI_DEFAULT_MODE BROTLI_MODE_GENERIC 65 66 /** Operations that can be performed by streaming encoder. */ 67 typedef enum BrotliEncoderOperation { 68 /** 69 * Process input. 70 * 71 * Encoder may postpone producing output, until it has processed enough input. 72 */ 73 BROTLI_OPERATION_PROCESS = 0, 74 /** 75 * Produce output for all processed input. 76 * 77 * Actual flush is performed when input stream is depleted and there is enough 78 * space in output stream. This means that client should repeat 79 * ::BROTLI_OPERATION_FLUSH operation until @p available_in becomes @c 0, and 80 * ::BrotliEncoderHasMoreOutput returns ::BROTLI_FALSE. If output is acquired 81 * via ::BrotliEncoderTakeOutput, then operation should be repeated after 82 * output buffer is drained. 83 * 84 * @warning Until flush is complete, client @b SHOULD @b NOT swap, 85 * reduce or extend input stream. 86 * 87 * When flush is complete, output data will be sufficient for decoder to 88 * reproduce all the given input. 89 */ 90 BROTLI_OPERATION_FLUSH = 1, 91 /** 92 * Finalize the stream. 93 * 94 * Actual finalization is performed when input stream is depleted and there is 95 * enough space in output stream. This means that client should repeat 96 * ::BROTLI_OPERATION_FINISH operation until @p available_in becomes @c 0, and 97 * ::BrotliEncoderHasMoreOutput returns ::BROTLI_FALSE. If output is acquired 98 * via ::BrotliEncoderTakeOutput, then operation should be repeated after 99 * output buffer is drained. 100 * 101 * @warning Until finalization is complete, client @b SHOULD @b NOT swap, 102 * reduce or extend input stream. 103 * 104 * Helper function ::BrotliEncoderIsFinished checks if stream is finalized and 105 * output fully dumped. 106 * 107 * Adding more input data to finalized stream is impossible. 108 */ 109 BROTLI_OPERATION_FINISH = 2, 110 /** 111 * Emit metadata block to stream. 112 * 113 * Metadata is opaque to Brotli: neither encoder, nor decoder processes this 114 * data or relies on it. It may be used to pass some extra information from 115 * encoder client to decoder client without interfering with main data stream. 116 * 117 * @note Encoder may emit empty metadata blocks internally, to pad encoded 118 * stream to byte boundary. 119 * 120 * @warning Until emitting metadata is complete client @b SHOULD @b NOT swap, 121 * reduce or extend input stream. 122 * 123 * @warning The whole content of input buffer is considered to be the content 124 * of metadata block. Do @b NOT @e append metadata to input stream, 125 * before it is depleted with other operations. 126 * 127 * Stream is soft-flushed before metadata block is emitted. Metadata block 128 * @b MUST be no longer than than 16MiB. 129 */ 130 BROTLI_OPERATION_EMIT_METADATA = 3 131 } BrotliEncoderOperation; 132 133 /** Options to be used with ::BrotliEncoderSetParameter. */ 134 typedef enum BrotliEncoderParameter { 135 /** 136 * Tune encoder for specific input. 137 * 138 * ::BrotliEncoderMode enumerates all available values. 139 */ 140 BROTLI_PARAM_MODE = 0, 141 /** 142 * The main compression speed-density lever. 143 * 144 * The higher the quality, the slower the compression. Range is 145 * from ::BROTLI_MIN_QUALITY to ::BROTLI_MAX_QUALITY. 146 */ 147 BROTLI_PARAM_QUALITY = 1, 148 /** 149 * Recommended sliding LZ77 window size. 150 * 151 * Encoder may reduce this value, e.g. if input is much smaller than 152 * window size. 153 * 154 * Window size is `(1 << value) - 16`. 155 * 156 * Range is from ::BROTLI_MIN_WINDOW_BITS to ::BROTLI_MAX_WINDOW_BITS. 157 */ 158 BROTLI_PARAM_LGWIN = 2, 159 /** 160 * Recommended input block size. 161 * 162 * Encoder may reduce this value, e.g. if input is much smaller than input 163 * block size. 164 * 165 * Range is from ::BROTLI_MIN_INPUT_BLOCK_BITS to 166 * ::BROTLI_MAX_INPUT_BLOCK_BITS. 167 * 168 * @note Bigger input block size allows better compression, but consumes more 169 * memory. \n The rough formula of memory used for temporary input 170 * storage is `3 << lgBlock`. 171 */ 172 BROTLI_PARAM_LGBLOCK = 3, 173 /** 174 * Flag that affects usage of "literal context modeling" format feature. 175 * 176 * This flag is a "decoding-speed vs compression ratio" trade-off. 177 */ 178 BROTLI_PARAM_DISABLE_LITERAL_CONTEXT_MODELING = 4, 179 /** 180 * Estimated total input size for all ::BrotliEncoderCompressStream calls. 181 * 182 * The default value is 0, which means that the total input size is unknown. 183 */ 184 BROTLI_PARAM_SIZE_HINT = 5, 185 /** 186 * Flag that determines if "Large Window Brotli" is used. 187 */ 188 BROTLI_PARAM_LARGE_WINDOW = 6, 189 /** 190 * Recommended number of postfix bits (NPOSTFIX). 191 * 192 * Encoder may change this value. 193 * 194 * Range is from 0 to ::BROTLI_MAX_NPOSTFIX. 195 */ 196 BROTLI_PARAM_NPOSTFIX = 7, 197 /** 198 * Recommended number of direct distance codes (NDIRECT). 199 * 200 * Encoder may change this value. 201 * 202 * Range is from 0 to (15 << NPOSTFIX) in steps of (1 << NPOSTFIX). 203 */ 204 BROTLI_PARAM_NDIRECT = 8 205 } BrotliEncoderParameter; 206 207 /** 208 * Opaque structure that holds encoder state. 209 * 210 * Allocated and initialized with ::BrotliEncoderCreateInstance. 211 * Cleaned up and deallocated with ::BrotliEncoderDestroyInstance. 212 */ 213 typedef struct BrotliEncoderStateStruct BrotliEncoderState; 214 215 /** 216 * Sets the specified parameter to the given encoder instance. 217 * 218 * @param state encoder instance 219 * @param param parameter to set 220 * @param value new parameter value 221 * @returns ::BROTLI_FALSE if parameter is unrecognized, or value is invalid 222 * @returns ::BROTLI_FALSE if value of parameter can not be changed at current 223 * encoder state (e.g. when encoding is started, window size might be 224 * already encoded and therefore it is impossible to change it) 225 * @returns ::BROTLI_TRUE if value is accepted 226 * @warning invalid values might be accepted in case they would not break 227 * encoding process. 228 */ 229 BROTLI_ENC_API BROTLI_BOOL BrotliEncoderSetParameter( 230 BrotliEncoderState* state, BrotliEncoderParameter param, uint32_t value); 231 232 /** 233 * Creates an instance of ::BrotliEncoderState and initializes it. 234 * 235 * @p alloc_func and @p free_func @b MUST be both zero or both non-zero. In the 236 * case they are both zero, default memory allocators are used. @p opaque is 237 * passed to @p alloc_func and @p free_func when they are called. @p free_func 238 * has to return without doing anything when asked to free a NULL pointer. 239 * 240 * @param alloc_func custom memory allocation function 241 * @param free_func custom memory free function 242 * @param opaque custom memory manager handle 243 * @returns @c 0 if instance can not be allocated or initialized 244 * @returns pointer to initialized ::BrotliEncoderState otherwise 245 */ 246 BROTLI_ENC_API BrotliEncoderState* BrotliEncoderCreateInstance( 247 brotli_alloc_func alloc_func, brotli_free_func free_func, void* opaque); 248 249 /** 250 * Deinitializes and frees ::BrotliEncoderState instance. 251 * 252 * @param state decoder instance to be cleaned up and deallocated 253 */ 254 BROTLI_ENC_API void BrotliEncoderDestroyInstance(BrotliEncoderState* state); 255 256 /** 257 * Calculates the output size bound for the given @p input_size. 258 * 259 * @warning Result is only valid if quality is at least @c 2 and, in 260 * case ::BrotliEncoderCompressStream was used, no flushes 261 * (::BROTLI_OPERATION_FLUSH) were performed. 262 * 263 * @param input_size size of projected input 264 * @returns @c 0 if result does not fit @c size_t 265 */ 266 BROTLI_ENC_API size_t BrotliEncoderMaxCompressedSize(size_t input_size); 267 268 /** 269 * Performs one-shot memory-to-memory compression. 270 * 271 * Compresses the data in @p input_buffer into @p encoded_buffer, and sets 272 * @p *encoded_size to the compressed length. 273 * 274 * @note If ::BrotliEncoderMaxCompressedSize(@p input_size) returns non-zero 275 * value, then output is guaranteed to be no longer than that. 276 * 277 * @param quality quality parameter value, e.g. ::BROTLI_DEFAULT_QUALITY 278 * @param lgwin lgwin parameter value, e.g. ::BROTLI_DEFAULT_WINDOW 279 * @param mode mode parameter value, e.g. ::BROTLI_DEFAULT_MODE 280 * @param input_size size of @p input_buffer 281 * @param input_buffer input data buffer with at least @p input_size 282 * addressable bytes 283 * @param[in, out] encoded_size @b in: size of @p encoded_buffer; \n 284 * @b out: length of compressed data written to 285 * @p encoded_buffer, or @c 0 if compression fails 286 * @param encoded_buffer compressed data destination buffer 287 * @returns ::BROTLI_FALSE in case of compression error 288 * @returns ::BROTLI_FALSE if output buffer is too small 289 * @returns ::BROTLI_TRUE otherwise 290 */ 291 BROTLI_ENC_API BROTLI_BOOL BrotliEncoderCompress( 292 int quality, int lgwin, BrotliEncoderMode mode, size_t input_size, 293 const uint8_t input_buffer[BROTLI_ARRAY_PARAM(input_size)], 294 size_t* encoded_size, 295 uint8_t encoded_buffer[BROTLI_ARRAY_PARAM(*encoded_size)]); 296 297 /** 298 * Compresses input stream to output stream. 299 * 300 * The values @p *available_in and @p *available_out must specify the number of 301 * bytes addressable at @p *next_in and @p *next_out respectively. 302 * When @p *available_out is @c 0, @p next_out is allowed to be @c NULL. 303 * 304 * After each call, @p *available_in will be decremented by the amount of input 305 * bytes consumed, and the @p *next_in pointer will be incremented by that 306 * amount. Similarly, @p *available_out will be decremented by the amount of 307 * output bytes written, and the @p *next_out pointer will be incremented by 308 * that amount. 309 * 310 * @p total_out, if it is not a null-pointer, will be set to the number 311 * of bytes compressed since the last @p state initialization. 312 * 313 * 314 * 315 * Internally workflow consists of 3 tasks: 316 * -# (optionally) copy input data to internal buffer 317 * -# actually compress data and (optionally) store it to internal buffer 318 * -# (optionally) copy compressed bytes from internal buffer to output stream 319 * 320 * Whenever all 3 tasks can't move forward anymore, or error occurs, this 321 * method returns the control flow to caller. 322 * 323 * @p op is used to perform flush, finish the stream, or inject metadata block. 324 * See ::BrotliEncoderOperation for more information. 325 * 326 * Flushing the stream means forcing encoding of all input passed to encoder and 327 * completing the current output block, so it could be fully decoded by stream 328 * decoder. To perform flush set @p op to ::BROTLI_OPERATION_FLUSH. 329 * Under some circumstances (e.g. lack of output stream capacity) this operation 330 * would require several calls to ::BrotliEncoderCompressStream. The method must 331 * be called again until both input stream is depleted and encoder has no more 332 * output (see ::BrotliEncoderHasMoreOutput) after the method is called. 333 * 334 * Finishing the stream means encoding of all input passed to encoder and 335 * adding specific "final" marks, so stream decoder could determine that stream 336 * is complete. To perform finish set @p op to ::BROTLI_OPERATION_FINISH. 337 * Under some circumstances (e.g. lack of output stream capacity) this operation 338 * would require several calls to ::BrotliEncoderCompressStream. The method must 339 * be called again until both input stream is depleted and encoder has no more 340 * output (see ::BrotliEncoderHasMoreOutput) after the method is called. 341 * 342 * @warning When flushing and finishing, @p op should not change until operation 343 * is complete; input stream should not be swapped, reduced or 344 * extended as well. 345 * 346 * @param state encoder instance 347 * @param op requested operation 348 * @param[in, out] available_in @b in: amount of available input; \n 349 * @b out: amount of unused input 350 * @param[in, out] next_in pointer to the next input byte 351 * @param[in, out] available_out @b in: length of output buffer; \n 352 * @b out: remaining size of output buffer 353 * @param[in, out] next_out compressed output buffer cursor; 354 * can be @c NULL if @p available_out is @c 0 355 * @param[out] total_out number of bytes produced so far; can be @c NULL 356 * @returns ::BROTLI_FALSE if there was an error 357 * @returns ::BROTLI_TRUE otherwise 358 */ 359 BROTLI_ENC_API BROTLI_BOOL BrotliEncoderCompressStream( 360 BrotliEncoderState* state, BrotliEncoderOperation op, size_t* available_in, 361 const uint8_t** next_in, size_t* available_out, uint8_t** next_out, 362 size_t* total_out); 363 364 /** 365 * Checks if encoder instance reached the final state. 366 * 367 * @param state encoder instance 368 * @returns ::BROTLI_TRUE if encoder is in a state where it reached the end of 369 * the input and produced all of the output 370 * @returns ::BROTLI_FALSE otherwise 371 */ 372 BROTLI_ENC_API BROTLI_BOOL BrotliEncoderIsFinished(BrotliEncoderState* state); 373 374 /** 375 * Checks if encoder has more output. 376 * 377 * @param state encoder instance 378 * @returns ::BROTLI_TRUE, if encoder has some unconsumed output 379 * @returns ::BROTLI_FALSE otherwise 380 */ 381 BROTLI_ENC_API BROTLI_BOOL BrotliEncoderHasMoreOutput( 382 BrotliEncoderState* state); 383 384 /** 385 * Acquires pointer to internal output buffer. 386 * 387 * This method is used to make language bindings easier and more efficient: 388 * -# push data to ::BrotliEncoderCompressStream, 389 * until ::BrotliEncoderHasMoreOutput returns BROTL_TRUE 390 * -# use ::BrotliEncoderTakeOutput to peek bytes and copy to language-specific 391 * entity 392 * 393 * Also this could be useful if there is an output stream that is able to 394 * consume all the provided data (e.g. when data is saved to file system). 395 * 396 * @attention After every call to ::BrotliEncoderTakeOutput @p *size bytes of 397 * output are considered consumed for all consecutive calls to the 398 * instance methods; returned pointer becomes invalidated as well. 399 * 400 * @note Encoder output is not guaranteed to be contiguous. This means that 401 * after the size-unrestricted call to ::BrotliEncoderTakeOutput, 402 * immediate next call to ::BrotliEncoderTakeOutput may return more data. 403 * 404 * @param state encoder instance 405 * @param[in, out] size @b in: number of bytes caller is ready to take, @c 0 if 406 * any amount could be handled; \n 407 * @b out: amount of data pointed by returned pointer and 408 * considered consumed; \n 409 * out value is never greater than in value, unless it is @c 0 410 * @returns pointer to output data 411 */ 412 BROTLI_ENC_API const uint8_t* BrotliEncoderTakeOutput( 413 BrotliEncoderState* state, size_t* size); 414 415 416 /** 417 * Gets an encoder library version. 418 * 419 * Look at BROTLI_VERSION for more information. 420 */ 421 BROTLI_ENC_API uint32_t BrotliEncoderVersion(void); 422 423 #if defined(__cplusplus) || defined(c_plusplus) 424 } /* extern "C" */ 425 #endif 426 427 #endif /* BROTLI_ENC_ENCODE_H_ */ 428