1 /* Copyright 2014 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 /* Brotli bit stream functions to support the low level format. There are no 8 compression algorithms here, just the right ordering of bits to match the 9 specs. */ 10 11 #include "./brotli_bit_stream.h" 12 13 #include <string.h> /* memcpy, memset */ 14 15 #include "../common/constants.h" 16 #include <brotli/types.h> 17 #include "./context.h" 18 #include "./entropy_encode.h" 19 #include "./entropy_encode_static.h" 20 #include "./fast_log.h" 21 #include "./memory.h" 22 #include "./port.h" 23 #include "./write_bits.h" 24 25 #if defined(__cplusplus) || defined(c_plusplus) 26 extern "C" { 27 #endif 28 29 #define MAX_HUFFMAN_TREE_SIZE (2 * BROTLI_NUM_COMMAND_SYMBOLS + 1) 30 /* The size of Huffman dictionary for distances assuming that NPOSTFIX = 0 and 31 NDIRECT = 0. */ 32 #define SIMPLE_DISTANCE_ALPHABET_SIZE (BROTLI_NUM_DISTANCE_SHORT_CODES + \ 33 (2 * BROTLI_MAX_DISTANCE_BITS)) 34 /* SIMPLE_DISTANCE_ALPHABET_SIZE == 64 */ 35 #define SIMPLE_DISTANCE_ALPHABET_BITS 6 36 37 /* Represents the range of values belonging to a prefix code: 38 [offset, offset + 2^nbits) */ 39 typedef struct PrefixCodeRange { 40 uint32_t offset; 41 uint32_t nbits; 42 } PrefixCodeRange; 43 44 static const PrefixCodeRange 45 kBlockLengthPrefixCode[BROTLI_NUM_BLOCK_LEN_SYMBOLS] = { 46 { 1, 2}, { 5, 2}, { 9, 2}, {13, 2}, {17, 3}, { 25, 3}, { 33, 3}, 47 {41, 3}, {49, 4}, {65, 4}, {81, 4}, {97, 4}, {113, 5}, {145, 5}, 48 {177, 5}, { 209, 5}, { 241, 6}, { 305, 6}, { 369, 7}, { 497, 8}, 49 {753, 9}, {1265, 10}, {2289, 11}, {4337, 12}, {8433, 13}, {16625, 24} 50 }; 51 52 static BROTLI_INLINE uint32_t BlockLengthPrefixCode(uint32_t len) { 53 uint32_t code = (len >= 177) ? (len >= 753 ? 20 : 14) : (len >= 41 ? 7 : 0); 54 while (code < (BROTLI_NUM_BLOCK_LEN_SYMBOLS - 1) && 55 len >= kBlockLengthPrefixCode[code + 1].offset) ++code; 56 return code; 57 } 58 59 static BROTLI_INLINE void GetBlockLengthPrefixCode(uint32_t len, size_t* code, 60 uint32_t* n_extra, uint32_t* extra) { 61 *code = BlockLengthPrefixCode(len); 62 *n_extra = kBlockLengthPrefixCode[*code].nbits; 63 *extra = len - kBlockLengthPrefixCode[*code].offset; 64 } 65 66 typedef struct BlockTypeCodeCalculator { 67 size_t last_type; 68 size_t second_last_type; 69 } BlockTypeCodeCalculator; 70 71 static void InitBlockTypeCodeCalculator(BlockTypeCodeCalculator* self) { 72 self->last_type = 1; 73 self->second_last_type = 0; 74 } 75 76 static BROTLI_INLINE size_t NextBlockTypeCode( 77 BlockTypeCodeCalculator* calculator, uint8_t type) { 78 size_t type_code = (type == calculator->last_type + 1) ? 1u : 79 (type == calculator->second_last_type) ? 0u : type + 2u; 80 calculator->second_last_type = calculator->last_type; 81 calculator->last_type = type; 82 return type_code; 83 } 84 85 /* |nibblesbits| represents the 2 bits to encode MNIBBLES (0-3) 86 REQUIRES: length > 0 87 REQUIRES: length <= (1 << 24) */ 88 static void BrotliEncodeMlen(size_t length, uint64_t* bits, 89 size_t* numbits, uint64_t* nibblesbits) { 90 size_t lg = (length == 1) ? 1 : Log2FloorNonZero((uint32_t)(length - 1)) + 1; 91 size_t mnibbles = (lg < 16 ? 16 : (lg + 3)) / 4; 92 assert(length > 0); 93 assert(length <= (1 << 24)); 94 assert(lg <= 24); 95 *nibblesbits = mnibbles - 4; 96 *numbits = mnibbles * 4; 97 *bits = length - 1; 98 } 99 100 static BROTLI_INLINE void StoreCommandExtra( 101 const Command* cmd, size_t* storage_ix, uint8_t* storage) { 102 uint32_t copylen_code = CommandCopyLenCode(cmd); 103 uint16_t inscode = GetInsertLengthCode(cmd->insert_len_); 104 uint16_t copycode = GetCopyLengthCode(copylen_code); 105 uint32_t insnumextra = GetInsertExtra(inscode); 106 uint64_t insextraval = cmd->insert_len_ - GetInsertBase(inscode); 107 uint64_t copyextraval = copylen_code - GetCopyBase(copycode); 108 uint64_t bits = (copyextraval << insnumextra) | insextraval; 109 BrotliWriteBits( 110 insnumextra + GetCopyExtra(copycode), bits, storage_ix, storage); 111 } 112 113 /* Data structure that stores almost everything that is needed to encode each 114 block switch command. */ 115 typedef struct BlockSplitCode { 116 BlockTypeCodeCalculator type_code_calculator; 117 uint8_t type_depths[BROTLI_MAX_BLOCK_TYPE_SYMBOLS]; 118 uint16_t type_bits[BROTLI_MAX_BLOCK_TYPE_SYMBOLS]; 119 uint8_t length_depths[BROTLI_NUM_BLOCK_LEN_SYMBOLS]; 120 uint16_t length_bits[BROTLI_NUM_BLOCK_LEN_SYMBOLS]; 121 } BlockSplitCode; 122 123 /* Stores a number between 0 and 255. */ 124 static void StoreVarLenUint8(size_t n, size_t* storage_ix, uint8_t* storage) { 125 if (n == 0) { 126 BrotliWriteBits(1, 0, storage_ix, storage); 127 } else { 128 size_t nbits = Log2FloorNonZero(n); 129 BrotliWriteBits(1, 1, storage_ix, storage); 130 BrotliWriteBits(3, nbits, storage_ix, storage); 131 BrotliWriteBits(nbits, n - ((size_t)1 << nbits), storage_ix, storage); 132 } 133 } 134 135 /* Stores the compressed meta-block header. 136 REQUIRES: length > 0 137 REQUIRES: length <= (1 << 24) */ 138 static void StoreCompressedMetaBlockHeader(BROTLI_BOOL is_final_block, 139 size_t length, 140 size_t* storage_ix, 141 uint8_t* storage) { 142 uint64_t lenbits; 143 size_t nlenbits; 144 uint64_t nibblesbits; 145 146 /* Write ISLAST bit. */ 147 BrotliWriteBits(1, (uint64_t)is_final_block, storage_ix, storage); 148 /* Write ISEMPTY bit. */ 149 if (is_final_block) { 150 BrotliWriteBits(1, 0, storage_ix, storage); 151 } 152 153 BrotliEncodeMlen(length, &lenbits, &nlenbits, &nibblesbits); 154 BrotliWriteBits(2, nibblesbits, storage_ix, storage); 155 BrotliWriteBits(nlenbits, lenbits, storage_ix, storage); 156 157 if (!is_final_block) { 158 /* Write ISUNCOMPRESSED bit. */ 159 BrotliWriteBits(1, 0, storage_ix, storage); 160 } 161 } 162 163 /* Stores the uncompressed meta-block header. 164 REQUIRES: length > 0 165 REQUIRES: length <= (1 << 24) */ 166 static void BrotliStoreUncompressedMetaBlockHeader(size_t length, 167 size_t* storage_ix, 168 uint8_t* storage) { 169 uint64_t lenbits; 170 size_t nlenbits; 171 uint64_t nibblesbits; 172 173 /* Write ISLAST bit. 174 Uncompressed block cannot be the last one, so set to 0. */ 175 BrotliWriteBits(1, 0, storage_ix, storage); 176 BrotliEncodeMlen(length, &lenbits, &nlenbits, &nibblesbits); 177 BrotliWriteBits(2, nibblesbits, storage_ix, storage); 178 BrotliWriteBits(nlenbits, lenbits, storage_ix, storage); 179 /* Write ISUNCOMPRESSED bit. */ 180 BrotliWriteBits(1, 1, storage_ix, storage); 181 } 182 183 static void BrotliStoreHuffmanTreeOfHuffmanTreeToBitMask( 184 const int num_codes, const uint8_t* code_length_bitdepth, 185 size_t* storage_ix, uint8_t* storage) { 186 static const uint8_t kStorageOrder[BROTLI_CODE_LENGTH_CODES] = { 187 1, 2, 3, 4, 0, 5, 17, 6, 16, 7, 8, 9, 10, 11, 12, 13, 14, 15 188 }; 189 /* The bit lengths of the Huffman code over the code length alphabet 190 are compressed with the following static Huffman code: 191 Symbol Code 192 ------ ---- 193 0 00 194 1 1110 195 2 110 196 3 01 197 4 10 198 5 1111 */ 199 static const uint8_t kHuffmanBitLengthHuffmanCodeSymbols[6] = { 200 0, 7, 3, 2, 1, 15 201 }; 202 static const uint8_t kHuffmanBitLengthHuffmanCodeBitLengths[6] = { 203 2, 4, 3, 2, 2, 4 204 }; 205 206 size_t skip_some = 0; /* skips none. */ 207 208 /* Throw away trailing zeros: */ 209 size_t codes_to_store = BROTLI_CODE_LENGTH_CODES; 210 if (num_codes > 1) { 211 for (; codes_to_store > 0; --codes_to_store) { 212 if (code_length_bitdepth[kStorageOrder[codes_to_store - 1]] != 0) { 213 break; 214 } 215 } 216 } 217 if (code_length_bitdepth[kStorageOrder[0]] == 0 && 218 code_length_bitdepth[kStorageOrder[1]] == 0) { 219 skip_some = 2; /* skips two. */ 220 if (code_length_bitdepth[kStorageOrder[2]] == 0) { 221 skip_some = 3; /* skips three. */ 222 } 223 } 224 BrotliWriteBits(2, skip_some, storage_ix, storage); 225 { 226 size_t i; 227 for (i = skip_some; i < codes_to_store; ++i) { 228 size_t l = code_length_bitdepth[kStorageOrder[i]]; 229 BrotliWriteBits(kHuffmanBitLengthHuffmanCodeBitLengths[l], 230 kHuffmanBitLengthHuffmanCodeSymbols[l], storage_ix, storage); 231 } 232 } 233 } 234 235 static void BrotliStoreHuffmanTreeToBitMask( 236 const size_t huffman_tree_size, const uint8_t* huffman_tree, 237 const uint8_t* huffman_tree_extra_bits, const uint8_t* code_length_bitdepth, 238 const uint16_t* code_length_bitdepth_symbols, 239 size_t* BROTLI_RESTRICT storage_ix, uint8_t* BROTLI_RESTRICT storage) { 240 size_t i; 241 for (i = 0; i < huffman_tree_size; ++i) { 242 size_t ix = huffman_tree[i]; 243 BrotliWriteBits(code_length_bitdepth[ix], code_length_bitdepth_symbols[ix], 244 storage_ix, storage); 245 /* Extra bits */ 246 switch (ix) { 247 case BROTLI_REPEAT_PREVIOUS_CODE_LENGTH: 248 BrotliWriteBits(2, huffman_tree_extra_bits[i], storage_ix, storage); 249 break; 250 case BROTLI_REPEAT_ZERO_CODE_LENGTH: 251 BrotliWriteBits(3, huffman_tree_extra_bits[i], storage_ix, storage); 252 break; 253 } 254 } 255 } 256 257 static void StoreSimpleHuffmanTree(const uint8_t* depths, 258 size_t symbols[4], 259 size_t num_symbols, 260 size_t max_bits, 261 size_t *storage_ix, uint8_t *storage) { 262 /* value of 1 indicates a simple Huffman code */ 263 BrotliWriteBits(2, 1, storage_ix, storage); 264 BrotliWriteBits(2, num_symbols - 1, storage_ix, storage); /* NSYM - 1 */ 265 266 { 267 /* Sort */ 268 size_t i; 269 for (i = 0; i < num_symbols; i++) { 270 size_t j; 271 for (j = i + 1; j < num_symbols; j++) { 272 if (depths[symbols[j]] < depths[symbols[i]]) { 273 BROTLI_SWAP(size_t, symbols, j, i); 274 } 275 } 276 } 277 } 278 279 if (num_symbols == 2) { 280 BrotliWriteBits(max_bits, symbols[0], storage_ix, storage); 281 BrotliWriteBits(max_bits, symbols[1], storage_ix, storage); 282 } else if (num_symbols == 3) { 283 BrotliWriteBits(max_bits, symbols[0], storage_ix, storage); 284 BrotliWriteBits(max_bits, symbols[1], storage_ix, storage); 285 BrotliWriteBits(max_bits, symbols[2], storage_ix, storage); 286 } else { 287 BrotliWriteBits(max_bits, symbols[0], storage_ix, storage); 288 BrotliWriteBits(max_bits, symbols[1], storage_ix, storage); 289 BrotliWriteBits(max_bits, symbols[2], storage_ix, storage); 290 BrotliWriteBits(max_bits, symbols[3], storage_ix, storage); 291 /* tree-select */ 292 BrotliWriteBits(1, depths[symbols[0]] == 1 ? 1 : 0, storage_ix, storage); 293 } 294 } 295 296 /* num = alphabet size 297 depths = symbol depths */ 298 void BrotliStoreHuffmanTree(const uint8_t* depths, size_t num, 299 HuffmanTree* tree, 300 size_t *storage_ix, uint8_t *storage) { 301 /* Write the Huffman tree into the brotli-representation. 302 The command alphabet is the largest, so this allocation will fit all 303 alphabets. */ 304 uint8_t huffman_tree[BROTLI_NUM_COMMAND_SYMBOLS]; 305 uint8_t huffman_tree_extra_bits[BROTLI_NUM_COMMAND_SYMBOLS]; 306 size_t huffman_tree_size = 0; 307 uint8_t code_length_bitdepth[BROTLI_CODE_LENGTH_CODES] = { 0 }; 308 uint16_t code_length_bitdepth_symbols[BROTLI_CODE_LENGTH_CODES]; 309 uint32_t huffman_tree_histogram[BROTLI_CODE_LENGTH_CODES] = { 0 }; 310 size_t i; 311 int num_codes = 0; 312 size_t code = 0; 313 314 assert(num <= BROTLI_NUM_COMMAND_SYMBOLS); 315 316 BrotliWriteHuffmanTree(depths, num, &huffman_tree_size, huffman_tree, 317 huffman_tree_extra_bits); 318 319 /* Calculate the statistics of the Huffman tree in brotli-representation. */ 320 for (i = 0; i < huffman_tree_size; ++i) { 321 ++huffman_tree_histogram[huffman_tree[i]]; 322 } 323 324 for (i = 0; i < BROTLI_CODE_LENGTH_CODES; ++i) { 325 if (huffman_tree_histogram[i]) { 326 if (num_codes == 0) { 327 code = i; 328 num_codes = 1; 329 } else if (num_codes == 1) { 330 num_codes = 2; 331 break; 332 } 333 } 334 } 335 336 /* Calculate another Huffman tree to use for compressing both the 337 earlier Huffman tree with. */ 338 BrotliCreateHuffmanTree(huffman_tree_histogram, BROTLI_CODE_LENGTH_CODES, 339 5, tree, code_length_bitdepth); 340 BrotliConvertBitDepthsToSymbols(code_length_bitdepth, 341 BROTLI_CODE_LENGTH_CODES, 342 code_length_bitdepth_symbols); 343 344 /* Now, we have all the data, let's start storing it */ 345 BrotliStoreHuffmanTreeOfHuffmanTreeToBitMask(num_codes, code_length_bitdepth, 346 storage_ix, storage); 347 348 if (num_codes == 1) { 349 code_length_bitdepth[code] = 0; 350 } 351 352 /* Store the real Huffman tree now. */ 353 BrotliStoreHuffmanTreeToBitMask(huffman_tree_size, 354 huffman_tree, 355 huffman_tree_extra_bits, 356 code_length_bitdepth, 357 code_length_bitdepth_symbols, 358 storage_ix, storage); 359 } 360 361 /* Builds a Huffman tree from histogram[0:length] into depth[0:length] and 362 bits[0:length] and stores the encoded tree to the bit stream. */ 363 static void BuildAndStoreHuffmanTree(const uint32_t *histogram, 364 const size_t length, 365 HuffmanTree* tree, 366 uint8_t* depth, 367 uint16_t* bits, 368 size_t* storage_ix, 369 uint8_t* storage) { 370 size_t count = 0; 371 size_t s4[4] = { 0 }; 372 size_t i; 373 size_t max_bits = 0; 374 for (i = 0; i < length; i++) { 375 if (histogram[i]) { 376 if (count < 4) { 377 s4[count] = i; 378 } else if (count > 4) { 379 break; 380 } 381 count++; 382 } 383 } 384 385 { 386 size_t max_bits_counter = length - 1; 387 while (max_bits_counter) { 388 max_bits_counter >>= 1; 389 ++max_bits; 390 } 391 } 392 393 if (count <= 1) { 394 BrotliWriteBits(4, 1, storage_ix, storage); 395 BrotliWriteBits(max_bits, s4[0], storage_ix, storage); 396 depth[s4[0]] = 0; 397 bits[s4[0]] = 0; 398 return; 399 } 400 401 memset(depth, 0, length * sizeof(depth[0])); 402 BrotliCreateHuffmanTree(histogram, length, 15, tree, depth); 403 BrotliConvertBitDepthsToSymbols(depth, length, bits); 404 405 if (count <= 4) { 406 StoreSimpleHuffmanTree(depth, s4, count, max_bits, storage_ix, storage); 407 } else { 408 BrotliStoreHuffmanTree(depth, length, tree, storage_ix, storage); 409 } 410 } 411 412 static BROTLI_INLINE BROTLI_BOOL SortHuffmanTree( 413 const HuffmanTree* v0, const HuffmanTree* v1) { 414 return TO_BROTLI_BOOL(v0->total_count_ < v1->total_count_); 415 } 416 417 void BrotliBuildAndStoreHuffmanTreeFast(MemoryManager* m, 418 const uint32_t* histogram, 419 const size_t histogram_total, 420 const size_t max_bits, 421 uint8_t* depth, uint16_t* bits, 422 size_t* storage_ix, 423 uint8_t* storage) { 424 size_t count = 0; 425 size_t symbols[4] = { 0 }; 426 size_t length = 0; 427 size_t total = histogram_total; 428 while (total != 0) { 429 if (histogram[length]) { 430 if (count < 4) { 431 symbols[count] = length; 432 } 433 ++count; 434 total -= histogram[length]; 435 } 436 ++length; 437 } 438 439 if (count <= 1) { 440 BrotliWriteBits(4, 1, storage_ix, storage); 441 BrotliWriteBits(max_bits, symbols[0], storage_ix, storage); 442 depth[symbols[0]] = 0; 443 bits[symbols[0]] = 0; 444 return; 445 } 446 447 memset(depth, 0, length * sizeof(depth[0])); 448 { 449 const size_t max_tree_size = 2 * length + 1; 450 HuffmanTree* tree = BROTLI_ALLOC(m, HuffmanTree, max_tree_size); 451 uint32_t count_limit; 452 if (BROTLI_IS_OOM(m)) return; 453 for (count_limit = 1; ; count_limit *= 2) { 454 HuffmanTree* node = tree; 455 size_t l; 456 for (l = length; l != 0;) { 457 --l; 458 if (histogram[l]) { 459 if (BROTLI_PREDICT_TRUE(histogram[l] >= count_limit)) { 460 InitHuffmanTree(node, histogram[l], -1, (int16_t)l); 461 } else { 462 InitHuffmanTree(node, count_limit, -1, (int16_t)l); 463 } 464 ++node; 465 } 466 } 467 { 468 const int n = (int)(node - tree); 469 HuffmanTree sentinel; 470 int i = 0; /* Points to the next leaf node. */ 471 int j = n + 1; /* Points to the next non-leaf node. */ 472 int k; 473 474 SortHuffmanTreeItems(tree, (size_t)n, SortHuffmanTree); 475 /* The nodes are: 476 [0, n): the sorted leaf nodes that we start with. 477 [n]: we add a sentinel here. 478 [n + 1, 2n): new parent nodes are added here, starting from 479 (n+1). These are naturally in ascending order. 480 [2n]: we add a sentinel at the end as well. 481 There will be (2n+1) elements at the end. */ 482 InitHuffmanTree(&sentinel, BROTLI_UINT32_MAX, -1, -1); 483 *node++ = sentinel; 484 *node++ = sentinel; 485 486 for (k = n - 1; k > 0; --k) { 487 int left, right; 488 if (tree[i].total_count_ <= tree[j].total_count_) { 489 left = i; 490 ++i; 491 } else { 492 left = j; 493 ++j; 494 } 495 if (tree[i].total_count_ <= tree[j].total_count_) { 496 right = i; 497 ++i; 498 } else { 499 right = j; 500 ++j; 501 } 502 /* The sentinel node becomes the parent node. */ 503 node[-1].total_count_ = 504 tree[left].total_count_ + tree[right].total_count_; 505 node[-1].index_left_ = (int16_t)left; 506 node[-1].index_right_or_value_ = (int16_t)right; 507 /* Add back the last sentinel node. */ 508 *node++ = sentinel; 509 } 510 if (BrotliSetDepth(2 * n - 1, tree, depth, 14)) { 511 /* We need to pack the Huffman tree in 14 bits. If this was not 512 successful, add fake entities to the lowest values and retry. */ 513 break; 514 } 515 } 516 } 517 BROTLI_FREE(m, tree); 518 } 519 BrotliConvertBitDepthsToSymbols(depth, length, bits); 520 if (count <= 4) { 521 size_t i; 522 /* value of 1 indicates a simple Huffman code */ 523 BrotliWriteBits(2, 1, storage_ix, storage); 524 BrotliWriteBits(2, count - 1, storage_ix, storage); /* NSYM - 1 */ 525 526 /* Sort */ 527 for (i = 0; i < count; i++) { 528 size_t j; 529 for (j = i + 1; j < count; j++) { 530 if (depth[symbols[j]] < depth[symbols[i]]) { 531 BROTLI_SWAP(size_t, symbols, j, i); 532 } 533 } 534 } 535 536 if (count == 2) { 537 BrotliWriteBits(max_bits, symbols[0], storage_ix, storage); 538 BrotliWriteBits(max_bits, symbols[1], storage_ix, storage); 539 } else if (count == 3) { 540 BrotliWriteBits(max_bits, symbols[0], storage_ix, storage); 541 BrotliWriteBits(max_bits, symbols[1], storage_ix, storage); 542 BrotliWriteBits(max_bits, symbols[2], storage_ix, storage); 543 } else { 544 BrotliWriteBits(max_bits, symbols[0], storage_ix, storage); 545 BrotliWriteBits(max_bits, symbols[1], storage_ix, storage); 546 BrotliWriteBits(max_bits, symbols[2], storage_ix, storage); 547 BrotliWriteBits(max_bits, symbols[3], storage_ix, storage); 548 /* tree-select */ 549 BrotliWriteBits(1, depth[symbols[0]] == 1 ? 1 : 0, storage_ix, storage); 550 } 551 } else { 552 uint8_t previous_value = 8; 553 size_t i; 554 /* Complex Huffman Tree */ 555 StoreStaticCodeLengthCode(storage_ix, storage); 556 557 /* Actual RLE coding. */ 558 for (i = 0; i < length;) { 559 const uint8_t value = depth[i]; 560 size_t reps = 1; 561 size_t k; 562 for (k = i + 1; k < length && depth[k] == value; ++k) { 563 ++reps; 564 } 565 i += reps; 566 if (value == 0) { 567 BrotliWriteBits(kZeroRepsDepth[reps], kZeroRepsBits[reps], 568 storage_ix, storage); 569 } else { 570 if (previous_value != value) { 571 BrotliWriteBits(kCodeLengthDepth[value], kCodeLengthBits[value], 572 storage_ix, storage); 573 --reps; 574 } 575 if (reps < 3) { 576 while (reps != 0) { 577 reps--; 578 BrotliWriteBits(kCodeLengthDepth[value], kCodeLengthBits[value], 579 storage_ix, storage); 580 } 581 } else { 582 reps -= 3; 583 BrotliWriteBits(kNonZeroRepsDepth[reps], kNonZeroRepsBits[reps], 584 storage_ix, storage); 585 } 586 previous_value = value; 587 } 588 } 589 } 590 } 591 592 static size_t IndexOf(const uint8_t* v, size_t v_size, uint8_t value) { 593 size_t i = 0; 594 for (; i < v_size; ++i) { 595 if (v[i] == value) return i; 596 } 597 return i; 598 } 599 600 static void MoveToFront(uint8_t* v, size_t index) { 601 uint8_t value = v[index]; 602 size_t i; 603 for (i = index; i != 0; --i) { 604 v[i] = v[i - 1]; 605 } 606 v[0] = value; 607 } 608 609 static void MoveToFrontTransform(const uint32_t* BROTLI_RESTRICT v_in, 610 const size_t v_size, 611 uint32_t* v_out) { 612 size_t i; 613 uint8_t mtf[256]; 614 uint32_t max_value; 615 if (v_size == 0) { 616 return; 617 } 618 max_value = v_in[0]; 619 for (i = 1; i < v_size; ++i) { 620 if (v_in[i] > max_value) max_value = v_in[i]; 621 } 622 assert(max_value < 256u); 623 for (i = 0; i <= max_value; ++i) { 624 mtf[i] = (uint8_t)i; 625 } 626 { 627 size_t mtf_size = max_value + 1; 628 for (i = 0; i < v_size; ++i) { 629 size_t index = IndexOf(mtf, mtf_size, (uint8_t)v_in[i]); 630 assert(index < mtf_size); 631 v_out[i] = (uint32_t)index; 632 MoveToFront(mtf, index); 633 } 634 } 635 } 636 637 /* Finds runs of zeros in v[0..in_size) and replaces them with a prefix code of 638 the run length plus extra bits (lower 9 bits is the prefix code and the rest 639 are the extra bits). Non-zero values in v[] are shifted by 640 *max_length_prefix. Will not create prefix codes bigger than the initial 641 value of *max_run_length_prefix. The prefix code of run length L is simply 642 Log2Floor(L) and the number of extra bits is the same as the prefix code. */ 643 static void RunLengthCodeZeros(const size_t in_size, 644 uint32_t* BROTLI_RESTRICT v, size_t* BROTLI_RESTRICT out_size, 645 uint32_t* BROTLI_RESTRICT max_run_length_prefix) { 646 uint32_t max_reps = 0; 647 size_t i; 648 uint32_t max_prefix; 649 for (i = 0; i < in_size;) { 650 uint32_t reps = 0; 651 for (; i < in_size && v[i] != 0; ++i) ; 652 for (; i < in_size && v[i] == 0; ++i) { 653 ++reps; 654 } 655 max_reps = BROTLI_MAX(uint32_t, reps, max_reps); 656 } 657 max_prefix = max_reps > 0 ? Log2FloorNonZero(max_reps) : 0; 658 max_prefix = BROTLI_MIN(uint32_t, max_prefix, *max_run_length_prefix); 659 *max_run_length_prefix = max_prefix; 660 *out_size = 0; 661 for (i = 0; i < in_size;) { 662 assert(*out_size <= i); 663 if (v[i] != 0) { 664 v[*out_size] = v[i] + *max_run_length_prefix; 665 ++i; 666 ++(*out_size); 667 } else { 668 uint32_t reps = 1; 669 size_t k; 670 for (k = i + 1; k < in_size && v[k] == 0; ++k) { 671 ++reps; 672 } 673 i += reps; 674 while (reps != 0) { 675 if (reps < (2u << max_prefix)) { 676 uint32_t run_length_prefix = Log2FloorNonZero(reps); 677 const uint32_t extra_bits = reps - (1u << run_length_prefix); 678 v[*out_size] = run_length_prefix + (extra_bits << 9); 679 ++(*out_size); 680 break; 681 } else { 682 const uint32_t extra_bits = (1u << max_prefix) - 1u; 683 v[*out_size] = max_prefix + (extra_bits << 9); 684 reps -= (2u << max_prefix) - 1u; 685 ++(*out_size); 686 } 687 } 688 } 689 } 690 } 691 692 #define SYMBOL_BITS 9 693 694 static void EncodeContextMap(MemoryManager* m, 695 const uint32_t* context_map, 696 size_t context_map_size, 697 size_t num_clusters, 698 HuffmanTree* tree, 699 size_t* storage_ix, uint8_t* storage) { 700 size_t i; 701 uint32_t* rle_symbols; 702 uint32_t max_run_length_prefix = 6; 703 size_t num_rle_symbols = 0; 704 uint32_t histogram[BROTLI_MAX_CONTEXT_MAP_SYMBOLS]; 705 static const uint32_t kSymbolMask = (1u << SYMBOL_BITS) - 1u; 706 uint8_t depths[BROTLI_MAX_CONTEXT_MAP_SYMBOLS]; 707 uint16_t bits[BROTLI_MAX_CONTEXT_MAP_SYMBOLS]; 708 709 StoreVarLenUint8(num_clusters - 1, storage_ix, storage); 710 711 if (num_clusters == 1) { 712 return; 713 } 714 715 rle_symbols = BROTLI_ALLOC(m, uint32_t, context_map_size); 716 if (BROTLI_IS_OOM(m)) return; 717 MoveToFrontTransform(context_map, context_map_size, rle_symbols); 718 RunLengthCodeZeros(context_map_size, rle_symbols, 719 &num_rle_symbols, &max_run_length_prefix); 720 memset(histogram, 0, sizeof(histogram)); 721 for (i = 0; i < num_rle_symbols; ++i) { 722 ++histogram[rle_symbols[i] & kSymbolMask]; 723 } 724 { 725 BROTLI_BOOL use_rle = TO_BROTLI_BOOL(max_run_length_prefix > 0); 726 BrotliWriteBits(1, (uint64_t)use_rle, storage_ix, storage); 727 if (use_rle) { 728 BrotliWriteBits(4, max_run_length_prefix - 1, storage_ix, storage); 729 } 730 } 731 BuildAndStoreHuffmanTree(histogram, num_clusters + max_run_length_prefix, 732 tree, depths, bits, storage_ix, storage); 733 for (i = 0; i < num_rle_symbols; ++i) { 734 const uint32_t rle_symbol = rle_symbols[i] & kSymbolMask; 735 const uint32_t extra_bits_val = rle_symbols[i] >> SYMBOL_BITS; 736 BrotliWriteBits(depths[rle_symbol], bits[rle_symbol], storage_ix, storage); 737 if (rle_symbol > 0 && rle_symbol <= max_run_length_prefix) { 738 BrotliWriteBits(rle_symbol, extra_bits_val, storage_ix, storage); 739 } 740 } 741 BrotliWriteBits(1, 1, storage_ix, storage); /* use move-to-front */ 742 BROTLI_FREE(m, rle_symbols); 743 } 744 745 /* Stores the block switch command with index block_ix to the bit stream. */ 746 static BROTLI_INLINE void StoreBlockSwitch(BlockSplitCode* code, 747 const uint32_t block_len, 748 const uint8_t block_type, 749 BROTLI_BOOL is_first_block, 750 size_t* storage_ix, 751 uint8_t* storage) { 752 size_t typecode = NextBlockTypeCode(&code->type_code_calculator, block_type); 753 size_t lencode; 754 uint32_t len_nextra; 755 uint32_t len_extra; 756 if (!is_first_block) { 757 BrotliWriteBits(code->type_depths[typecode], code->type_bits[typecode], 758 storage_ix, storage); 759 } 760 GetBlockLengthPrefixCode(block_len, &lencode, &len_nextra, &len_extra); 761 762 BrotliWriteBits(code->length_depths[lencode], code->length_bits[lencode], 763 storage_ix, storage); 764 BrotliWriteBits(len_nextra, len_extra, storage_ix, storage); 765 } 766 767 /* Builds a BlockSplitCode data structure from the block split given by the 768 vector of block types and block lengths and stores it to the bit stream. */ 769 static void BuildAndStoreBlockSplitCode(const uint8_t* types, 770 const uint32_t* lengths, 771 const size_t num_blocks, 772 const size_t num_types, 773 HuffmanTree* tree, 774 BlockSplitCode* code, 775 size_t* storage_ix, 776 uint8_t* storage) { 777 uint32_t type_histo[BROTLI_MAX_BLOCK_TYPE_SYMBOLS]; 778 uint32_t length_histo[BROTLI_NUM_BLOCK_LEN_SYMBOLS]; 779 size_t i; 780 BlockTypeCodeCalculator type_code_calculator; 781 memset(type_histo, 0, (num_types + 2) * sizeof(type_histo[0])); 782 memset(length_histo, 0, sizeof(length_histo)); 783 InitBlockTypeCodeCalculator(&type_code_calculator); 784 for (i = 0; i < num_blocks; ++i) { 785 size_t type_code = NextBlockTypeCode(&type_code_calculator, types[i]); 786 if (i != 0) ++type_histo[type_code]; 787 ++length_histo[BlockLengthPrefixCode(lengths[i])]; 788 } 789 StoreVarLenUint8(num_types - 1, storage_ix, storage); 790 if (num_types > 1) { /* TODO: else? could StoreBlockSwitch occur? */ 791 BuildAndStoreHuffmanTree(&type_histo[0], num_types + 2, tree, 792 &code->type_depths[0], &code->type_bits[0], 793 storage_ix, storage); 794 BuildAndStoreHuffmanTree(&length_histo[0], BROTLI_NUM_BLOCK_LEN_SYMBOLS, 795 tree, &code->length_depths[0], 796 &code->length_bits[0], storage_ix, storage); 797 StoreBlockSwitch(code, lengths[0], types[0], 1, storage_ix, storage); 798 } 799 } 800 801 /* Stores a context map where the histogram type is always the block type. */ 802 static void StoreTrivialContextMap(size_t num_types, 803 size_t context_bits, 804 HuffmanTree* tree, 805 size_t* storage_ix, 806 uint8_t* storage) { 807 StoreVarLenUint8(num_types - 1, storage_ix, storage); 808 if (num_types > 1) { 809 size_t repeat_code = context_bits - 1u; 810 size_t repeat_bits = (1u << repeat_code) - 1u; 811 size_t alphabet_size = num_types + repeat_code; 812 uint32_t histogram[BROTLI_MAX_CONTEXT_MAP_SYMBOLS]; 813 uint8_t depths[BROTLI_MAX_CONTEXT_MAP_SYMBOLS]; 814 uint16_t bits[BROTLI_MAX_CONTEXT_MAP_SYMBOLS]; 815 size_t i; 816 memset(histogram, 0, alphabet_size * sizeof(histogram[0])); 817 /* Write RLEMAX. */ 818 BrotliWriteBits(1, 1, storage_ix, storage); 819 BrotliWriteBits(4, repeat_code - 1, storage_ix, storage); 820 histogram[repeat_code] = (uint32_t)num_types; 821 histogram[0] = 1; 822 for (i = context_bits; i < alphabet_size; ++i) { 823 histogram[i] = 1; 824 } 825 BuildAndStoreHuffmanTree(histogram, alphabet_size, tree, 826 depths, bits, storage_ix, storage); 827 for (i = 0; i < num_types; ++i) { 828 size_t code = (i == 0 ? 0 : i + context_bits - 1); 829 BrotliWriteBits(depths[code], bits[code], storage_ix, storage); 830 BrotliWriteBits( 831 depths[repeat_code], bits[repeat_code], storage_ix, storage); 832 BrotliWriteBits(repeat_code, repeat_bits, storage_ix, storage); 833 } 834 /* Write IMTF (inverse-move-to-front) bit. */ 835 BrotliWriteBits(1, 1, storage_ix, storage); 836 } 837 } 838 839 /* Manages the encoding of one block category (literal, command or distance). */ 840 typedef struct BlockEncoder { 841 size_t alphabet_size_; 842 size_t num_block_types_; 843 const uint8_t* block_types_; /* Not owned. */ 844 const uint32_t* block_lengths_; /* Not owned. */ 845 size_t num_blocks_; 846 BlockSplitCode block_split_code_; 847 size_t block_ix_; 848 size_t block_len_; 849 size_t entropy_ix_; 850 uint8_t* depths_; 851 uint16_t* bits_; 852 } BlockEncoder; 853 854 static void InitBlockEncoder(BlockEncoder* self, size_t alphabet_size, 855 size_t num_block_types, const uint8_t* block_types, 856 const uint32_t* block_lengths, const size_t num_blocks) { 857 self->alphabet_size_ = alphabet_size; 858 self->num_block_types_ = num_block_types; 859 self->block_types_ = block_types; 860 self->block_lengths_ = block_lengths; 861 self->num_blocks_ = num_blocks; 862 InitBlockTypeCodeCalculator(&self->block_split_code_.type_code_calculator); 863 self->block_ix_ = 0; 864 self->block_len_ = num_blocks == 0 ? 0 : block_lengths[0]; 865 self->entropy_ix_ = 0; 866 self->depths_ = 0; 867 self->bits_ = 0; 868 } 869 870 static void CleanupBlockEncoder(MemoryManager* m, BlockEncoder* self) { 871 BROTLI_FREE(m, self->depths_); 872 BROTLI_FREE(m, self->bits_); 873 } 874 875 /* Creates entropy codes of block lengths and block types and stores them 876 to the bit stream. */ 877 static void BuildAndStoreBlockSwitchEntropyCodes(BlockEncoder* self, 878 HuffmanTree* tree, size_t* storage_ix, uint8_t* storage) { 879 BuildAndStoreBlockSplitCode(self->block_types_, self->block_lengths_, 880 self->num_blocks_, self->num_block_types_, tree, &self->block_split_code_, 881 storage_ix, storage); 882 } 883 884 /* Stores the next symbol with the entropy code of the current block type. 885 Updates the block type and block length at block boundaries. */ 886 static void StoreSymbol(BlockEncoder* self, size_t symbol, size_t* storage_ix, 887 uint8_t* storage) { 888 if (self->block_len_ == 0) { 889 size_t block_ix = ++self->block_ix_; 890 uint32_t block_len = self->block_lengths_[block_ix]; 891 uint8_t block_type = self->block_types_[block_ix]; 892 self->block_len_ = block_len; 893 self->entropy_ix_ = block_type * self->alphabet_size_; 894 StoreBlockSwitch(&self->block_split_code_, block_len, block_type, 0, 895 storage_ix, storage); 896 } 897 --self->block_len_; 898 { 899 size_t ix = self->entropy_ix_ + symbol; 900 BrotliWriteBits(self->depths_[ix], self->bits_[ix], storage_ix, storage); 901 } 902 } 903 904 /* Stores the next symbol with the entropy code of the current block type and 905 context value. 906 Updates the block type and block length at block boundaries. */ 907 static void StoreSymbolWithContext(BlockEncoder* self, size_t symbol, 908 size_t context, const uint32_t* context_map, size_t* storage_ix, 909 uint8_t* storage, const size_t context_bits) { 910 if (self->block_len_ == 0) { 911 size_t block_ix = ++self->block_ix_; 912 uint32_t block_len = self->block_lengths_[block_ix]; 913 uint8_t block_type = self->block_types_[block_ix]; 914 self->block_len_ = block_len; 915 self->entropy_ix_ = (size_t)block_type << context_bits; 916 StoreBlockSwitch(&self->block_split_code_, block_len, block_type, 0, 917 storage_ix, storage); 918 } 919 --self->block_len_; 920 { 921 size_t histo_ix = context_map[self->entropy_ix_ + context]; 922 size_t ix = histo_ix * self->alphabet_size_ + symbol; 923 BrotliWriteBits(self->depths_[ix], self->bits_[ix], storage_ix, storage); 924 } 925 } 926 927 #define FN(X) X ## Literal 928 /* NOLINTNEXTLINE(build/include) */ 929 #include "./block_encoder_inc.h" 930 #undef FN 931 932 #define FN(X) X ## Command 933 /* NOLINTNEXTLINE(build/include) */ 934 #include "./block_encoder_inc.h" 935 #undef FN 936 937 #define FN(X) X ## Distance 938 /* NOLINTNEXTLINE(build/include) */ 939 #include "./block_encoder_inc.h" 940 #undef FN 941 942 static void JumpToByteBoundary(size_t* storage_ix, uint8_t* storage) { 943 *storage_ix = (*storage_ix + 7u) & ~7u; 944 storage[*storage_ix >> 3] = 0; 945 } 946 947 void BrotliStoreMetaBlock(MemoryManager* m, 948 const uint8_t* input, 949 size_t start_pos, 950 size_t length, 951 size_t mask, 952 uint8_t prev_byte, 953 uint8_t prev_byte2, 954 BROTLI_BOOL is_last, 955 uint32_t num_direct_distance_codes, 956 uint32_t distance_postfix_bits, 957 ContextType literal_context_mode, 958 const Command *commands, 959 size_t n_commands, 960 const MetaBlockSplit* mb, 961 size_t *storage_ix, 962 uint8_t *storage) { 963 size_t pos = start_pos; 964 size_t i; 965 size_t num_distance_codes = 966 BROTLI_NUM_DISTANCE_SHORT_CODES + num_direct_distance_codes + 967 (48u << distance_postfix_bits); 968 HuffmanTree* tree; 969 BlockEncoder literal_enc; 970 BlockEncoder command_enc; 971 BlockEncoder distance_enc; 972 973 StoreCompressedMetaBlockHeader(is_last, length, storage_ix, storage); 974 975 tree = BROTLI_ALLOC(m, HuffmanTree, MAX_HUFFMAN_TREE_SIZE); 976 if (BROTLI_IS_OOM(m)) return; 977 InitBlockEncoder(&literal_enc, 256, mb->literal_split.num_types, 978 mb->literal_split.types, mb->literal_split.lengths, 979 mb->literal_split.num_blocks); 980 InitBlockEncoder(&command_enc, BROTLI_NUM_COMMAND_SYMBOLS, 981 mb->command_split.num_types, mb->command_split.types, 982 mb->command_split.lengths, mb->command_split.num_blocks); 983 InitBlockEncoder(&distance_enc, num_distance_codes, 984 mb->distance_split.num_types, mb->distance_split.types, 985 mb->distance_split.lengths, mb->distance_split.num_blocks); 986 987 BuildAndStoreBlockSwitchEntropyCodes(&literal_enc, tree, storage_ix, storage); 988 BuildAndStoreBlockSwitchEntropyCodes(&command_enc, tree, storage_ix, storage); 989 BuildAndStoreBlockSwitchEntropyCodes( 990 &distance_enc, tree, storage_ix, storage); 991 992 BrotliWriteBits(2, distance_postfix_bits, storage_ix, storage); 993 BrotliWriteBits(4, num_direct_distance_codes >> distance_postfix_bits, 994 storage_ix, storage); 995 for (i = 0; i < mb->literal_split.num_types; ++i) { 996 BrotliWriteBits(2, literal_context_mode, storage_ix, storage); 997 } 998 999 if (mb->literal_context_map_size == 0) { 1000 StoreTrivialContextMap(mb->literal_histograms_size, 1001 BROTLI_LITERAL_CONTEXT_BITS, tree, storage_ix, storage); 1002 } else { 1003 EncodeContextMap(m, 1004 mb->literal_context_map, mb->literal_context_map_size, 1005 mb->literal_histograms_size, tree, storage_ix, storage); 1006 if (BROTLI_IS_OOM(m)) return; 1007 } 1008 1009 if (mb->distance_context_map_size == 0) { 1010 StoreTrivialContextMap(mb->distance_histograms_size, 1011 BROTLI_DISTANCE_CONTEXT_BITS, tree, storage_ix, storage); 1012 } else { 1013 EncodeContextMap(m, 1014 mb->distance_context_map, mb->distance_context_map_size, 1015 mb->distance_histograms_size, tree, storage_ix, storage); 1016 if (BROTLI_IS_OOM(m)) return; 1017 } 1018 1019 BuildAndStoreEntropyCodesLiteral(m, &literal_enc, mb->literal_histograms, 1020 mb->literal_histograms_size, tree, storage_ix, storage); 1021 if (BROTLI_IS_OOM(m)) return; 1022 BuildAndStoreEntropyCodesCommand(m, &command_enc, mb->command_histograms, 1023 mb->command_histograms_size, tree, storage_ix, storage); 1024 if (BROTLI_IS_OOM(m)) return; 1025 BuildAndStoreEntropyCodesDistance(m, &distance_enc, mb->distance_histograms, 1026 mb->distance_histograms_size, tree, storage_ix, storage); 1027 if (BROTLI_IS_OOM(m)) return; 1028 BROTLI_FREE(m, tree); 1029 1030 for (i = 0; i < n_commands; ++i) { 1031 const Command cmd = commands[i]; 1032 size_t cmd_code = cmd.cmd_prefix_; 1033 StoreSymbol(&command_enc, cmd_code, storage_ix, storage); 1034 StoreCommandExtra(&cmd, storage_ix, storage); 1035 if (mb->literal_context_map_size == 0) { 1036 size_t j; 1037 for (j = cmd.insert_len_; j != 0; --j) { 1038 StoreSymbol(&literal_enc, input[pos & mask], storage_ix, storage); 1039 ++pos; 1040 } 1041 } else { 1042 size_t j; 1043 for (j = cmd.insert_len_; j != 0; --j) { 1044 size_t context = Context(prev_byte, prev_byte2, literal_context_mode); 1045 uint8_t literal = input[pos & mask]; 1046 StoreSymbolWithContext(&literal_enc, literal, context, 1047 mb->literal_context_map, storage_ix, storage, 1048 BROTLI_LITERAL_CONTEXT_BITS); 1049 prev_byte2 = prev_byte; 1050 prev_byte = literal; 1051 ++pos; 1052 } 1053 } 1054 pos += CommandCopyLen(&cmd); 1055 if (CommandCopyLen(&cmd)) { 1056 prev_byte2 = input[(pos - 2) & mask]; 1057 prev_byte = input[(pos - 1) & mask]; 1058 if (cmd.cmd_prefix_ >= 128) { 1059 size_t dist_code = cmd.dist_prefix_; 1060 uint32_t distnumextra = cmd.dist_extra_ >> 24; 1061 uint64_t distextra = cmd.dist_extra_ & 0xffffff; 1062 if (mb->distance_context_map_size == 0) { 1063 StoreSymbol(&distance_enc, dist_code, storage_ix, storage); 1064 } else { 1065 size_t context = CommandDistanceContext(&cmd); 1066 StoreSymbolWithContext(&distance_enc, dist_code, context, 1067 mb->distance_context_map, storage_ix, storage, 1068 BROTLI_DISTANCE_CONTEXT_BITS); 1069 } 1070 BrotliWriteBits(distnumextra, distextra, storage_ix, storage); 1071 } 1072 } 1073 } 1074 CleanupBlockEncoder(m, &distance_enc); 1075 CleanupBlockEncoder(m, &command_enc); 1076 CleanupBlockEncoder(m, &literal_enc); 1077 if (is_last) { 1078 JumpToByteBoundary(storage_ix, storage); 1079 } 1080 } 1081 1082 static void BuildHistograms(const uint8_t* input, 1083 size_t start_pos, 1084 size_t mask, 1085 const Command *commands, 1086 size_t n_commands, 1087 HistogramLiteral* lit_histo, 1088 HistogramCommand* cmd_histo, 1089 HistogramDistance* dist_histo) { 1090 size_t pos = start_pos; 1091 size_t i; 1092 for (i = 0; i < n_commands; ++i) { 1093 const Command cmd = commands[i]; 1094 size_t j; 1095 HistogramAddCommand(cmd_histo, cmd.cmd_prefix_); 1096 for (j = cmd.insert_len_; j != 0; --j) { 1097 HistogramAddLiteral(lit_histo, input[pos & mask]); 1098 ++pos; 1099 } 1100 pos += CommandCopyLen(&cmd); 1101 if (CommandCopyLen(&cmd) && cmd.cmd_prefix_ >= 128) { 1102 HistogramAddDistance(dist_histo, cmd.dist_prefix_); 1103 } 1104 } 1105 } 1106 1107 static void StoreDataWithHuffmanCodes(const uint8_t* input, 1108 size_t start_pos, 1109 size_t mask, 1110 const Command *commands, 1111 size_t n_commands, 1112 const uint8_t* lit_depth, 1113 const uint16_t* lit_bits, 1114 const uint8_t* cmd_depth, 1115 const uint16_t* cmd_bits, 1116 const uint8_t* dist_depth, 1117 const uint16_t* dist_bits, 1118 size_t* storage_ix, 1119 uint8_t* storage) { 1120 size_t pos = start_pos; 1121 size_t i; 1122 for (i = 0; i < n_commands; ++i) { 1123 const Command cmd = commands[i]; 1124 const size_t cmd_code = cmd.cmd_prefix_; 1125 size_t j; 1126 BrotliWriteBits( 1127 cmd_depth[cmd_code], cmd_bits[cmd_code], storage_ix, storage); 1128 StoreCommandExtra(&cmd, storage_ix, storage); 1129 for (j = cmd.insert_len_; j != 0; --j) { 1130 const uint8_t literal = input[pos & mask]; 1131 BrotliWriteBits( 1132 lit_depth[literal], lit_bits[literal], storage_ix, storage); 1133 ++pos; 1134 } 1135 pos += CommandCopyLen(&cmd); 1136 if (CommandCopyLen(&cmd) && cmd.cmd_prefix_ >= 128) { 1137 const size_t dist_code = cmd.dist_prefix_; 1138 const uint32_t distnumextra = cmd.dist_extra_ >> 24; 1139 const uint32_t distextra = cmd.dist_extra_ & 0xffffff; 1140 BrotliWriteBits(dist_depth[dist_code], dist_bits[dist_code], 1141 storage_ix, storage); 1142 BrotliWriteBits(distnumextra, distextra, storage_ix, storage); 1143 } 1144 } 1145 } 1146 1147 void BrotliStoreMetaBlockTrivial(MemoryManager* m, 1148 const uint8_t* input, 1149 size_t start_pos, 1150 size_t length, 1151 size_t mask, 1152 BROTLI_BOOL is_last, 1153 const Command *commands, 1154 size_t n_commands, 1155 size_t *storage_ix, 1156 uint8_t *storage) { 1157 HistogramLiteral lit_histo; 1158 HistogramCommand cmd_histo; 1159 HistogramDistance dist_histo; 1160 uint8_t lit_depth[BROTLI_NUM_LITERAL_SYMBOLS]; 1161 uint16_t lit_bits[BROTLI_NUM_LITERAL_SYMBOLS]; 1162 uint8_t cmd_depth[BROTLI_NUM_COMMAND_SYMBOLS]; 1163 uint16_t cmd_bits[BROTLI_NUM_COMMAND_SYMBOLS]; 1164 uint8_t dist_depth[SIMPLE_DISTANCE_ALPHABET_SIZE]; 1165 uint16_t dist_bits[SIMPLE_DISTANCE_ALPHABET_SIZE]; 1166 HuffmanTree* tree; 1167 1168 StoreCompressedMetaBlockHeader(is_last, length, storage_ix, storage); 1169 1170 HistogramClearLiteral(&lit_histo); 1171 HistogramClearCommand(&cmd_histo); 1172 HistogramClearDistance(&dist_histo); 1173 1174 BuildHistograms(input, start_pos, mask, commands, n_commands, 1175 &lit_histo, &cmd_histo, &dist_histo); 1176 1177 BrotliWriteBits(13, 0, storage_ix, storage); 1178 1179 tree = BROTLI_ALLOC(m, HuffmanTree, MAX_HUFFMAN_TREE_SIZE); 1180 if (BROTLI_IS_OOM(m)) return; 1181 BuildAndStoreHuffmanTree(lit_histo.data_, BROTLI_NUM_LITERAL_SYMBOLS, tree, 1182 lit_depth, lit_bits, 1183 storage_ix, storage); 1184 BuildAndStoreHuffmanTree(cmd_histo.data_, BROTLI_NUM_COMMAND_SYMBOLS, tree, 1185 cmd_depth, cmd_bits, 1186 storage_ix, storage); 1187 BuildAndStoreHuffmanTree(dist_histo.data_, SIMPLE_DISTANCE_ALPHABET_SIZE, 1188 tree, 1189 dist_depth, dist_bits, 1190 storage_ix, storage); 1191 BROTLI_FREE(m, tree); 1192 StoreDataWithHuffmanCodes(input, start_pos, mask, commands, 1193 n_commands, lit_depth, lit_bits, 1194 cmd_depth, cmd_bits, 1195 dist_depth, dist_bits, 1196 storage_ix, storage); 1197 if (is_last) { 1198 JumpToByteBoundary(storage_ix, storage); 1199 } 1200 } 1201 1202 void BrotliStoreMetaBlockFast(MemoryManager* m, 1203 const uint8_t* input, 1204 size_t start_pos, 1205 size_t length, 1206 size_t mask, 1207 BROTLI_BOOL is_last, 1208 const Command *commands, 1209 size_t n_commands, 1210 size_t *storage_ix, 1211 uint8_t *storage) { 1212 StoreCompressedMetaBlockHeader(is_last, length, storage_ix, storage); 1213 1214 BrotliWriteBits(13, 0, storage_ix, storage); 1215 1216 if (n_commands <= 128) { 1217 uint32_t histogram[BROTLI_NUM_LITERAL_SYMBOLS] = { 0 }; 1218 size_t pos = start_pos; 1219 size_t num_literals = 0; 1220 size_t i; 1221 uint8_t lit_depth[BROTLI_NUM_LITERAL_SYMBOLS]; 1222 uint16_t lit_bits[BROTLI_NUM_LITERAL_SYMBOLS]; 1223 for (i = 0; i < n_commands; ++i) { 1224 const Command cmd = commands[i]; 1225 size_t j; 1226 for (j = cmd.insert_len_; j != 0; --j) { 1227 ++histogram[input[pos & mask]]; 1228 ++pos; 1229 } 1230 num_literals += cmd.insert_len_; 1231 pos += CommandCopyLen(&cmd); 1232 } 1233 BrotliBuildAndStoreHuffmanTreeFast(m, histogram, num_literals, 1234 /* max_bits = */ 8, 1235 lit_depth, lit_bits, 1236 storage_ix, storage); 1237 if (BROTLI_IS_OOM(m)) return; 1238 StoreStaticCommandHuffmanTree(storage_ix, storage); 1239 StoreStaticDistanceHuffmanTree(storage_ix, storage); 1240 StoreDataWithHuffmanCodes(input, start_pos, mask, commands, 1241 n_commands, lit_depth, lit_bits, 1242 kStaticCommandCodeDepth, 1243 kStaticCommandCodeBits, 1244 kStaticDistanceCodeDepth, 1245 kStaticDistanceCodeBits, 1246 storage_ix, storage); 1247 } else { 1248 HistogramLiteral lit_histo; 1249 HistogramCommand cmd_histo; 1250 HistogramDistance dist_histo; 1251 uint8_t lit_depth[BROTLI_NUM_LITERAL_SYMBOLS]; 1252 uint16_t lit_bits[BROTLI_NUM_LITERAL_SYMBOLS]; 1253 uint8_t cmd_depth[BROTLI_NUM_COMMAND_SYMBOLS]; 1254 uint16_t cmd_bits[BROTLI_NUM_COMMAND_SYMBOLS]; 1255 uint8_t dist_depth[SIMPLE_DISTANCE_ALPHABET_SIZE]; 1256 uint16_t dist_bits[SIMPLE_DISTANCE_ALPHABET_SIZE]; 1257 HistogramClearLiteral(&lit_histo); 1258 HistogramClearCommand(&cmd_histo); 1259 HistogramClearDistance(&dist_histo); 1260 BuildHistograms(input, start_pos, mask, commands, n_commands, 1261 &lit_histo, &cmd_histo, &dist_histo); 1262 BrotliBuildAndStoreHuffmanTreeFast(m, lit_histo.data_, 1263 lit_histo.total_count_, 1264 /* max_bits = */ 8, 1265 lit_depth, lit_bits, 1266 storage_ix, storage); 1267 if (BROTLI_IS_OOM(m)) return; 1268 BrotliBuildAndStoreHuffmanTreeFast(m, cmd_histo.data_, 1269 cmd_histo.total_count_, 1270 /* max_bits = */ 10, 1271 cmd_depth, cmd_bits, 1272 storage_ix, storage); 1273 if (BROTLI_IS_OOM(m)) return; 1274 BrotliBuildAndStoreHuffmanTreeFast(m, dist_histo.data_, 1275 dist_histo.total_count_, 1276 /* max_bits = */ 1277 SIMPLE_DISTANCE_ALPHABET_BITS, 1278 dist_depth, dist_bits, 1279 storage_ix, storage); 1280 if (BROTLI_IS_OOM(m)) return; 1281 StoreDataWithHuffmanCodes(input, start_pos, mask, commands, 1282 n_commands, lit_depth, lit_bits, 1283 cmd_depth, cmd_bits, 1284 dist_depth, dist_bits, 1285 storage_ix, storage); 1286 } 1287 1288 if (is_last) { 1289 JumpToByteBoundary(storage_ix, storage); 1290 } 1291 } 1292 1293 /* This is for storing uncompressed blocks (simple raw storage of 1294 bytes-as-bytes). */ 1295 void BrotliStoreUncompressedMetaBlock(BROTLI_BOOL is_final_block, 1296 const uint8_t * BROTLI_RESTRICT input, 1297 size_t position, size_t mask, 1298 size_t len, 1299 size_t * BROTLI_RESTRICT storage_ix, 1300 uint8_t * BROTLI_RESTRICT storage) { 1301 size_t masked_pos = position & mask; 1302 BrotliStoreUncompressedMetaBlockHeader(len, storage_ix, storage); 1303 JumpToByteBoundary(storage_ix, storage); 1304 1305 if (masked_pos + len > mask + 1) { 1306 size_t len1 = mask + 1 - masked_pos; 1307 memcpy(&storage[*storage_ix >> 3], &input[masked_pos], len1); 1308 *storage_ix += len1 << 3; 1309 len -= len1; 1310 masked_pos = 0; 1311 } 1312 memcpy(&storage[*storage_ix >> 3], &input[masked_pos], len); 1313 *storage_ix += len << 3; 1314 1315 /* We need to clear the next 4 bytes to continue to be 1316 compatible with BrotliWriteBits. */ 1317 BrotliWriteBitsPrepareStorage(*storage_ix, storage); 1318 1319 /* Since the uncompressed block itself may not be the final block, add an 1320 empty one after this. */ 1321 if (is_final_block) { 1322 BrotliWriteBits(1, 1, storage_ix, storage); /* islast */ 1323 BrotliWriteBits(1, 1, storage_ix, storage); /* isempty */ 1324 JumpToByteBoundary(storage_ix, storage); 1325 } 1326 } 1327 1328 void BrotliStoreSyncMetaBlock(size_t* BROTLI_RESTRICT storage_ix, 1329 uint8_t* BROTLI_RESTRICT storage) { 1330 /* Empty metadata meta-block bit pattern: 1331 1 bit: is_last (0) 1332 2 bits: num nibbles (3) 1333 1 bit: reserved (0) 1334 2 bits: metadata length bytes (0) */ 1335 BrotliWriteBits(6, 6, storage_ix, storage); 1336 JumpToByteBoundary(storage_ix, storage); 1337 } 1338 1339 #if defined(__cplusplus) || defined(c_plusplus) 1340 } /* extern "C" */ 1341 #endif 1342
