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 "../common/context.h"
17#include "../common/platform.h"
18#include <brotli/types.h>
19#include "./entropy_encode.h"
20#include "./entropy_encode_static.h"
21#include "./fast_log.h"
22#include "./histogram.h"
23#include "./memory.h"
24#include "./write_bits.h"
25
26#if defined(__cplusplus) || defined(c_plusplus)
27extern "C" {
28#endif
29
30#define MAX_HUFFMAN_TREE_SIZE (2 * BROTLI_NUM_COMMAND_SYMBOLS + 1)
31/* The maximum size of Huffman dictionary for distances assuming that
32 NPOSTFIX = 0 and NDIRECT = 0. */
33#define MAX_SIMPLE_DISTANCE_ALPHABET_SIZE \
34 BROTLI_DISTANCE_ALPHABET_SIZE(0, 0, BROTLI_LARGE_MAX_DISTANCE_BITS)
35/* MAX_SIMPLE_DISTANCE_ALPHABET_SIZE == 140 */
36
37/* Represents the range of values belonging to a prefix code:
38 [offset, offset + 2^nbits) */
39typedef struct PrefixCodeRange {
40 uint32_t offset;
41 uint32_t nbits;
42} PrefixCodeRange;
43
44static 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
52static 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
59static 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
66typedef struct BlockTypeCodeCalculator {
67 size_t last_type;
68 size_t second_last_type;
69} BlockTypeCodeCalculator;
70
71static void InitBlockTypeCodeCalculator(BlockTypeCodeCalculator* self) {
72 self->last_type = 1;
73 self->second_last_type = 0;
74}
75
76static 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) */
88static 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 BROTLI_DCHECK(length > 0);
93 BROTLI_DCHECK(length <= (1 << 24));
94 BROTLI_DCHECK(lg <= 24);
95 *nibblesbits = mnibbles - 4;
96 *numbits = mnibbles * 4;
97 *bits = length - 1;
98}
99
100static 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. */
115typedef 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. */
124static 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) */
138static 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) */
166static 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
183static 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
235static 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
257static 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 */
298void 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 BROTLI_DCHECK(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. */
363static void BuildAndStoreHuffmanTree(const uint32_t* histogram,
364 const size_t histogram_length,
365 const size_t alphabet_size,
366 HuffmanTree* tree,
367 uint8_t* depth,
368 uint16_t* bits,
369 size_t* storage_ix,
370 uint8_t* storage) {
371 size_t count = 0;
372 size_t s4[4] = { 0 };
373 size_t i;
374 size_t max_bits = 0;
375 for (i = 0; i < histogram_length; i++) {
376 if (histogram[i]) {
377 if (count < 4) {
378 s4[count] = i;
379 } else if (count > 4) {
380 break;
381 }
382 count++;
383 }
384 }
385
386 {
387 size_t max_bits_counter = alphabet_size - 1;
388 while (max_bits_counter) {
389 max_bits_counter >>= 1;
390 ++max_bits;
391 }
392 }
393
394 if (count <= 1) {
395 BrotliWriteBits(4, 1, storage_ix, storage);
396 BrotliWriteBits(max_bits, s4[0], storage_ix, storage);
397 depth[s4[0]] = 0;
398 bits[s4[0]] = 0;
399 return;
400 }
401
402 memset(depth, 0, histogram_length * sizeof(depth[0]));
403 BrotliCreateHuffmanTree(histogram, histogram_length, 15, tree, depth);
404 BrotliConvertBitDepthsToSymbols(depth, histogram_length, bits);
405
406 if (count <= 4) {
407 StoreSimpleHuffmanTree(depth, s4, count, max_bits, storage_ix, storage);
408 } else {
409 BrotliStoreHuffmanTree(depth, histogram_length, tree, storage_ix, storage);
410 }
411}
412
413static BROTLI_INLINE BROTLI_BOOL SortHuffmanTree(
414 const HuffmanTree* v0, const HuffmanTree* v1) {
415 return TO_BROTLI_BOOL(v0->total_count_ < v1->total_count_);
416}
417
418void BrotliBuildAndStoreHuffmanTreeFast(MemoryManager* m,
419 const uint32_t* histogram,
420 const size_t histogram_total,
421 const size_t max_bits,
422 uint8_t* depth, uint16_t* bits,
423 size_t* storage_ix,
424 uint8_t* storage) {
425 size_t count = 0;
426 size_t symbols[4] = { 0 };
427 size_t length = 0;
428 size_t total = histogram_total;
429 while (total != 0) {
430 if (histogram[length]) {
431 if (count < 4) {
432 symbols[count] = length;
433 }
434 ++count;
435 total -= histogram[length];
436 }
437 ++length;
438 }
439
440 if (count <= 1) {
441 BrotliWriteBits(4, 1, storage_ix, storage);
442 BrotliWriteBits(max_bits, symbols[0], storage_ix, storage);
443 depth[symbols[0]] = 0;
444 bits[symbols[0]] = 0;
445 return;
446 }
447
448 memset(depth, 0, length * sizeof(depth[0]));
449 {
450 const size_t max_tree_size = 2 * length + 1;
451 HuffmanTree* tree = BROTLI_ALLOC(m, HuffmanTree, max_tree_size);
452 uint32_t count_limit;
453 if (BROTLI_IS_OOM(m)) return;
454 for (count_limit = 1; ; count_limit *= 2) {
455 HuffmanTree* node = tree;
456 size_t l;
457 for (l = length; l != 0;) {
458 --l;
459 if (histogram[l]) {
460 if (BROTLI_PREDICT_TRUE(histogram[l] >= count_limit)) {
461 InitHuffmanTree(node, histogram[l], -1, (int16_t)l);
462 } else {
463 InitHuffmanTree(node, count_limit, -1, (int16_t)l);
464 }
465 ++node;
466 }
467 }
468 {
469 const int n = (int)(node - tree);
470 HuffmanTree sentinel;
471 int i = 0; /* Points to the next leaf node. */
472 int j = n + 1; /* Points to the next non-leaf node. */
473 int k;
474
475 SortHuffmanTreeItems(tree, (size_t)n, SortHuffmanTree);
476 /* The nodes are:
477 [0, n): the sorted leaf nodes that we start with.
478 [n]: we add a sentinel here.
479 [n + 1, 2n): new parent nodes are added here, starting from
480 (n+1). These are naturally in ascending order.
481 [2n]: we add a sentinel at the end as well.
482 There will be (2n+1) elements at the end. */
483 InitHuffmanTree(&sentinel, BROTLI_UINT32_MAX, -1, -1);
484 *node++ = sentinel;
485 *node++ = sentinel;
486
487 for (k = n - 1; k > 0; --k) {
488 int left, right;
489 if (tree[i].total_count_ <= tree[j].total_count_) {
490 left = i;
491 ++i;
492 } else {
493 left = j;
494 ++j;
495 }
496 if (tree[i].total_count_ <= tree[j].total_count_) {
497 right = i;
498 ++i;
499 } else {
500 right = j;
501 ++j;
502 }
503 /* The sentinel node becomes the parent node. */
504 node[-1].total_count_ =
505 tree[left].total_count_ + tree[right].total_count_;
506 node[-1].index_left_ = (int16_t)left;
507 node[-1].index_right_or_value_ = (int16_t)right;
508 /* Add back the last sentinel node. */
509 *node++ = sentinel;
510 }
511 if (BrotliSetDepth(2 * n - 1, tree, depth, 14)) {
512 /* We need to pack the Huffman tree in 14 bits. If this was not
513 successful, add fake entities to the lowest values and retry. */
514 break;
515 }
516 }
517 }
518 BROTLI_FREE(m, tree);
519 }
520 BrotliConvertBitDepthsToSymbols(depth, length, bits);
521 if (count <= 4) {
522 size_t i;
523 /* value of 1 indicates a simple Huffman code */
524 BrotliWriteBits(2, 1, storage_ix, storage);
525 BrotliWriteBits(2, count - 1, storage_ix, storage); /* NSYM - 1 */
526
527 /* Sort */
528 for (i = 0; i < count; i++) {
529 size_t j;
530 for (j = i + 1; j < count; j++) {
531 if (depth[symbols[j]] < depth[symbols[i]]) {
532 BROTLI_SWAP(size_t, symbols, j, i);
533 }
534 }
535 }
536
537 if (count == 2) {
538 BrotliWriteBits(max_bits, symbols[0], storage_ix, storage);
539 BrotliWriteBits(max_bits, symbols[1], storage_ix, storage);
540 } else if (count == 3) {
541 BrotliWriteBits(max_bits, symbols[0], storage_ix, storage);
542 BrotliWriteBits(max_bits, symbols[1], storage_ix, storage);
543 BrotliWriteBits(max_bits, symbols[2], storage_ix, storage);
544 } else {
545 BrotliWriteBits(max_bits, symbols[0], storage_ix, storage);
546 BrotliWriteBits(max_bits, symbols[1], storage_ix, storage);
547 BrotliWriteBits(max_bits, symbols[2], storage_ix, storage);
548 BrotliWriteBits(max_bits, symbols[3], storage_ix, storage);
549 /* tree-select */
550 BrotliWriteBits(1, depth[symbols[0]] == 1 ? 1 : 0, storage_ix, storage);
551 }
552 } else {
553 uint8_t previous_value = 8;
554 size_t i;
555 /* Complex Huffman Tree */
556 StoreStaticCodeLengthCode(storage_ix, storage);
557
558 /* Actual RLE coding. */
559 for (i = 0; i < length;) {
560 const uint8_t value = depth[i];
561 size_t reps = 1;
562 size_t k;
563 for (k = i + 1; k < length && depth[k] == value; ++k) {
564 ++reps;
565 }
566 i += reps;
567 if (value == 0) {
568 BrotliWriteBits(kZeroRepsDepth[reps], kZeroRepsBits[reps],
569 storage_ix, storage);
570 } else {
571 if (previous_value != value) {
572 BrotliWriteBits(kCodeLengthDepth[value], kCodeLengthBits[value],
573 storage_ix, storage);
574 --reps;
575 }
576 if (reps < 3) {
577 while (reps != 0) {
578 reps--;
579 BrotliWriteBits(kCodeLengthDepth[value], kCodeLengthBits[value],
580 storage_ix, storage);
581 }
582 } else {
583 reps -= 3;
584 BrotliWriteBits(kNonZeroRepsDepth[reps], kNonZeroRepsBits[reps],
585 storage_ix, storage);
586 }
587 previous_value = value;
588 }
589 }
590 }
591}
592
593static size_t IndexOf(const uint8_t* v, size_t v_size, uint8_t value) {
594 size_t i = 0;
595 for (; i < v_size; ++i) {
596 if (v[i] == value) return i;
597 }
598 return i;
599}
600
601static void MoveToFront(uint8_t* v, size_t index) {
602 uint8_t value = v[index];
603 size_t i;
604 for (i = index; i != 0; --i) {
605 v[i] = v[i - 1];
606 }
607 v[0] = value;
608}
609
610static void MoveToFrontTransform(const uint32_t* BROTLI_RESTRICT v_in,
611 const size_t v_size,
612 uint32_t* v_out) {
613 size_t i;
614 uint8_t mtf[256];
615 uint32_t max_value;
616 if (v_size == 0) {
617 return;
618 }
619 max_value = v_in[0];
620 for (i = 1; i < v_size; ++i) {
621 if (v_in[i] > max_value) max_value = v_in[i];
622 }
623 BROTLI_DCHECK(max_value < 256u);
624 for (i = 0; i <= max_value; ++i) {
625 mtf[i] = (uint8_t)i;
626 }
627 {
628 size_t mtf_size = max_value + 1;
629 for (i = 0; i < v_size; ++i) {
630 size_t index = IndexOf(mtf, mtf_size, (uint8_t)v_in[i]);
631 BROTLI_DCHECK(index < mtf_size);
632 v_out[i] = (uint32_t)index;
633 MoveToFront(mtf, index);
634 }
635 }
636}
637
638/* Finds runs of zeros in v[0..in_size) and replaces them with a prefix code of
639 the run length plus extra bits (lower 9 bits is the prefix code and the rest
640 are the extra bits). Non-zero values in v[] are shifted by
641 *max_length_prefix. Will not create prefix codes bigger than the initial
642 value of *max_run_length_prefix. The prefix code of run length L is simply
643 Log2Floor(L) and the number of extra bits is the same as the prefix code. */
644static void RunLengthCodeZeros(const size_t in_size,
645 uint32_t* BROTLI_RESTRICT v, size_t* BROTLI_RESTRICT out_size,
646 uint32_t* BROTLI_RESTRICT max_run_length_prefix) {
647 uint32_t max_reps = 0;
648 size_t i;
649 uint32_t max_prefix;
650 for (i = 0; i < in_size;) {
651 uint32_t reps = 0;
652 for (; i < in_size && v[i] != 0; ++i) ;
653 for (; i < in_size && v[i] == 0; ++i) {
654 ++reps;
655 }
656 max_reps = BROTLI_MAX(uint32_t, reps, max_reps);
657 }
658 max_prefix = max_reps > 0 ? Log2FloorNonZero(max_reps) : 0;
659 max_prefix = BROTLI_MIN(uint32_t, max_prefix, *max_run_length_prefix);
660 *max_run_length_prefix = max_prefix;
661 *out_size = 0;
662 for (i = 0; i < in_size;) {
663 BROTLI_DCHECK(*out_size <= i);
664 if (v[i] != 0) {
665 v[*out_size] = v[i] + *max_run_length_prefix;
666 ++i;
667 ++(*out_size);
668 } else {
669 uint32_t reps = 1;
670 size_t k;
671 for (k = i + 1; k < in_size && v[k] == 0; ++k) {
672 ++reps;
673 }
674 i += reps;
675 while (reps != 0) {
676 if (reps < (2u << max_prefix)) {
677 uint32_t run_length_prefix = Log2FloorNonZero(reps);
678 const uint32_t extra_bits = reps - (1u << run_length_prefix);
679 v[*out_size] = run_length_prefix + (extra_bits << 9);
680 ++(*out_size);
681 break;
682 } else {
683 const uint32_t extra_bits = (1u << max_prefix) - 1u;
684 v[*out_size] = max_prefix + (extra_bits << 9);
685 reps -= (2u << max_prefix) - 1u;
686 ++(*out_size);
687 }
688 }
689 }
690 }
691}
692
693#define SYMBOL_BITS 9
694
695static void EncodeContextMap(MemoryManager* m,
696 const uint32_t* context_map,
697 size_t context_map_size,
698 size_t num_clusters,
699 HuffmanTree* tree,
700 size_t* storage_ix, uint8_t* storage) {
701 size_t i;
702 uint32_t* rle_symbols;
703 uint32_t max_run_length_prefix = 6;
704 size_t num_rle_symbols = 0;
705 uint32_t histogram[BROTLI_MAX_CONTEXT_MAP_SYMBOLS];
706 static const uint32_t kSymbolMask = (1u << SYMBOL_BITS) - 1u;
707 uint8_t depths[BROTLI_MAX_CONTEXT_MAP_SYMBOLS];
708 uint16_t bits[BROTLI_MAX_CONTEXT_MAP_SYMBOLS];
709
710 StoreVarLenUint8(num_clusters - 1, storage_ix, storage);
711
712 if (num_clusters == 1) {
713 return;
714 }
715
716 rle_symbols = BROTLI_ALLOC(m, uint32_t, context_map_size);
717 if (BROTLI_IS_OOM(m)) return;
718 MoveToFrontTransform(context_map, context_map_size, rle_symbols);
719 RunLengthCodeZeros(context_map_size, rle_symbols,
720 &num_rle_symbols, &max_run_length_prefix);
721 memset(histogram, 0, sizeof(histogram));
722 for (i = 0; i < num_rle_symbols; ++i) {
723 ++histogram[rle_symbols[i] & kSymbolMask];
724 }
725 {
726 BROTLI_BOOL use_rle = TO_BROTLI_BOOL(max_run_length_prefix > 0);
727 BrotliWriteBits(1, (uint64_t)use_rle, storage_ix, storage);
728 if (use_rle) {
729 BrotliWriteBits(4, max_run_length_prefix - 1, storage_ix, storage);
730 }
731 }
732 BuildAndStoreHuffmanTree(histogram, num_clusters + max_run_length_prefix,
733 num_clusters + max_run_length_prefix,
734 tree, depths, bits, storage_ix, storage);
735 for (i = 0; i < num_rle_symbols; ++i) {
736 const uint32_t rle_symbol = rle_symbols[i] & kSymbolMask;
737 const uint32_t extra_bits_val = rle_symbols[i] >> SYMBOL_BITS;
738 BrotliWriteBits(depths[rle_symbol], bits[rle_symbol], storage_ix, storage);
739 if (rle_symbol > 0 && rle_symbol <= max_run_length_prefix) {
740 BrotliWriteBits(rle_symbol, extra_bits_val, storage_ix, storage);
741 }
742 }
743 BrotliWriteBits(1, 1, storage_ix, storage); /* use move-to-front */
744 BROTLI_FREE(m, rle_symbols);
745}
746
747/* Stores the block switch command with index block_ix to the bit stream. */
748static BROTLI_INLINE void StoreBlockSwitch(BlockSplitCode* code,
749 const uint32_t block_len,
750 const uint8_t block_type,
751 BROTLI_BOOL is_first_block,
752 size_t* storage_ix,
753 uint8_t* storage) {
754 size_t typecode = NextBlockTypeCode(&code->type_code_calculator, block_type);
755 size_t lencode;
756 uint32_t len_nextra;
757 uint32_t len_extra;
758 if (!is_first_block) {
759 BrotliWriteBits(code->type_depths[typecode], code->type_bits[typecode],
760 storage_ix, storage);
761 }
762 GetBlockLengthPrefixCode(block_len, &lencode, &len_nextra, &len_extra);
763
764 BrotliWriteBits(code->length_depths[lencode], code->length_bits[lencode],
765 storage_ix, storage);
766 BrotliWriteBits(len_nextra, len_extra, storage_ix, storage);
767}
768
769/* Builds a BlockSplitCode data structure from the block split given by the
770 vector of block types and block lengths and stores it to the bit stream. */
771static void BuildAndStoreBlockSplitCode(const uint8_t* types,
772 const uint32_t* lengths,
773 const size_t num_blocks,
774 const size_t num_types,
775 HuffmanTree* tree,
776 BlockSplitCode* code,
777 size_t* storage_ix,
778 uint8_t* storage) {
779 uint32_t type_histo[BROTLI_MAX_BLOCK_TYPE_SYMBOLS];
780 uint32_t length_histo[BROTLI_NUM_BLOCK_LEN_SYMBOLS];
781 size_t i;
782 BlockTypeCodeCalculator type_code_calculator;
783 memset(type_histo, 0, (num_types + 2) * sizeof(type_histo[0]));
784 memset(length_histo, 0, sizeof(length_histo));
785 InitBlockTypeCodeCalculator(&type_code_calculator);
786 for (i = 0; i < num_blocks; ++i) {
787 size_t type_code = NextBlockTypeCode(&type_code_calculator, types[i]);
788 if (i != 0) ++type_histo[type_code];
789 ++length_histo[BlockLengthPrefixCode(lengths[i])];
790 }
791 StoreVarLenUint8(num_types - 1, storage_ix, storage);
792 if (num_types > 1) { /* TODO: else? could StoreBlockSwitch occur? */
793 BuildAndStoreHuffmanTree(&type_histo[0], num_types + 2, num_types + 2, tree,
794 &code->type_depths[0], &code->type_bits[0],
795 storage_ix, storage);
796 BuildAndStoreHuffmanTree(&length_histo[0], BROTLI_NUM_BLOCK_LEN_SYMBOLS,
797 BROTLI_NUM_BLOCK_LEN_SYMBOLS,
798 tree, &code->length_depths[0],
799 &code->length_bits[0], storage_ix, storage);
800 StoreBlockSwitch(code, lengths[0], types[0], 1, storage_ix, storage);
801 }
802}
803
804/* Stores a context map where the histogram type is always the block type. */
805static void StoreTrivialContextMap(size_t num_types,
806 size_t context_bits,
807 HuffmanTree* tree,
808 size_t* storage_ix,
809 uint8_t* storage) {
810 StoreVarLenUint8(num_types - 1, storage_ix, storage);
811 if (num_types > 1) {
812 size_t repeat_code = context_bits - 1u;
813 size_t repeat_bits = (1u << repeat_code) - 1u;
814 size_t alphabet_size = num_types + repeat_code;
815 uint32_t histogram[BROTLI_MAX_CONTEXT_MAP_SYMBOLS];
816 uint8_t depths[BROTLI_MAX_CONTEXT_MAP_SYMBOLS];
817 uint16_t bits[BROTLI_MAX_CONTEXT_MAP_SYMBOLS];
818 size_t i;
819 memset(histogram, 0, alphabet_size * sizeof(histogram[0]));
820 /* Write RLEMAX. */
821 BrotliWriteBits(1, 1, storage_ix, storage);
822 BrotliWriteBits(4, repeat_code - 1, storage_ix, storage);
823 histogram[repeat_code] = (uint32_t)num_types;
824 histogram[0] = 1;
825 for (i = context_bits; i < alphabet_size; ++i) {
826 histogram[i] = 1;
827 }
828 BuildAndStoreHuffmanTree(histogram, alphabet_size, alphabet_size,
829 tree, depths, bits, storage_ix, storage);
830 for (i = 0; i < num_types; ++i) {
831 size_t code = (i == 0 ? 0 : i + context_bits - 1);
832 BrotliWriteBits(depths[code], bits[code], storage_ix, storage);
833 BrotliWriteBits(
834 depths[repeat_code], bits[repeat_code], storage_ix, storage);
835 BrotliWriteBits(repeat_code, repeat_bits, storage_ix, storage);
836 }
837 /* Write IMTF (inverse-move-to-front) bit. */
838 BrotliWriteBits(1, 1, storage_ix, storage);
839 }
840}
841
842/* Manages the encoding of one block category (literal, command or distance). */
843typedef struct BlockEncoder {
844 size_t histogram_length_;
845 size_t num_block_types_;
846 const uint8_t* block_types_; /* Not owned. */
847 const uint32_t* block_lengths_; /* Not owned. */
848 size_t num_blocks_;
849 BlockSplitCode block_split_code_;
850 size_t block_ix_;
851 size_t block_len_;
852 size_t entropy_ix_;
853 uint8_t* depths_;
854 uint16_t* bits_;
855} BlockEncoder;
856
857static void InitBlockEncoder(BlockEncoder* self, size_t histogram_length,
858 size_t num_block_types, const uint8_t* block_types,
859 const uint32_t* block_lengths, const size_t num_blocks) {
860 self->histogram_length_ = histogram_length;
861 self->num_block_types_ = num_block_types;
862 self->block_types_ = block_types;
863 self->block_lengths_ = block_lengths;
864 self->num_blocks_ = num_blocks;
865 InitBlockTypeCodeCalculator(&self->block_split_code_.type_code_calculator);
866 self->block_ix_ = 0;
867 self->block_len_ = num_blocks == 0 ? 0 : block_lengths[0];
868 self->entropy_ix_ = 0;
869 self->depths_ = 0;
870 self->bits_ = 0;
871}
872
873static void CleanupBlockEncoder(MemoryManager* m, BlockEncoder* self) {
874 BROTLI_FREE(m, self->depths_);
875 BROTLI_FREE(m, self->bits_);
876}
877
878/* Creates entropy codes of block lengths and block types and stores them
879 to the bit stream. */
880static void BuildAndStoreBlockSwitchEntropyCodes(BlockEncoder* self,
881 HuffmanTree* tree, size_t* storage_ix, uint8_t* storage) {
882 BuildAndStoreBlockSplitCode(self->block_types_, self->block_lengths_,
883 self->num_blocks_, self->num_block_types_, tree, &self->block_split_code_,
884 storage_ix, storage);
885}
886
887/* Stores the next symbol with the entropy code of the current block type.
888 Updates the block type and block length at block boundaries. */
889static void StoreSymbol(BlockEncoder* self, size_t symbol, size_t* storage_ix,
890 uint8_t* storage) {
891 if (self->block_len_ == 0) {
892 size_t block_ix = ++self->block_ix_;
893 uint32_t block_len = self->block_lengths_[block_ix];
894 uint8_t block_type = self->block_types_[block_ix];
895 self->block_len_ = block_len;
896 self->entropy_ix_ = block_type * self->histogram_length_;
897 StoreBlockSwitch(&self->block_split_code_, block_len, block_type, 0,
898 storage_ix, storage);
899 }
900 --self->block_len_;
901 {
902 size_t ix = self->entropy_ix_ + symbol;
903 BrotliWriteBits(self->depths_[ix], self->bits_[ix], storage_ix, storage);
904 }
905}
906
907/* Stores the next symbol with the entropy code of the current block type and
908 context value.
909 Updates the block type and block length at block boundaries. */
910static void StoreSymbolWithContext(BlockEncoder* self, size_t symbol,
911 size_t context, const uint32_t* context_map, size_t* storage_ix,
912 uint8_t* storage, const size_t context_bits) {
913 if (self->block_len_ == 0) {
914 size_t block_ix = ++self->block_ix_;
915 uint32_t block_len = self->block_lengths_[block_ix];
916 uint8_t block_type = self->block_types_[block_ix];
917 self->block_len_ = block_len;
918 self->entropy_ix_ = (size_t)block_type << context_bits;
919 StoreBlockSwitch(&self->block_split_code_, block_len, block_type, 0,
920 storage_ix, storage);
921 }
922 --self->block_len_;
923 {
924 size_t histo_ix = context_map[self->entropy_ix_ + context];
925 size_t ix = histo_ix * self->histogram_length_ + symbol;
926 BrotliWriteBits(self->depths_[ix], self->bits_[ix], storage_ix, storage);
927 }
928}
929
930#define FN(X) X ## Literal
931/* NOLINTNEXTLINE(build/include) */
932#include "./block_encoder_inc.h"
933#undef FN
934
935#define FN(X) X ## Command
936/* NOLINTNEXTLINE(build/include) */
937#include "./block_encoder_inc.h"
938#undef FN
939
940#define FN(X) X ## Distance
941/* NOLINTNEXTLINE(build/include) */
942#include "./block_encoder_inc.h"
943#undef FN
944
945static void JumpToByteBoundary(size_t* storage_ix, uint8_t* storage) {
946 *storage_ix = (*storage_ix + 7u) & ~7u;
947 storage[*storage_ix >> 3] = 0;
948}
949
950void BrotliStoreMetaBlock(MemoryManager* m,
951 const uint8_t* input, size_t start_pos, size_t length, size_t mask,
952 uint8_t prev_byte, uint8_t prev_byte2, BROTLI_BOOL is_last,
953 const BrotliEncoderParams* params, ContextType literal_context_mode,
954 const Command* commands, size_t n_commands, const MetaBlockSplit* mb,
955 size_t* storage_ix, uint8_t* storage) {
956
957 size_t pos = start_pos;
958 size_t i;
959 uint32_t num_distance_symbols = params->dist.alphabet_size;
960 uint32_t num_effective_distance_symbols = num_distance_symbols;
961 HuffmanTree* tree;
962 ContextLut literal_context_lut = BROTLI_CONTEXT_LUT(literal_context_mode);
963 BlockEncoder literal_enc;
964 BlockEncoder command_enc;
965 BlockEncoder distance_enc;
966 const BrotliDistanceParams* dist = &params->dist;
967 if (params->large_window &&
968 num_effective_distance_symbols > BROTLI_NUM_HISTOGRAM_DISTANCE_SYMBOLS) {
969 num_effective_distance_symbols = BROTLI_NUM_HISTOGRAM_DISTANCE_SYMBOLS;
970 }
971
972 StoreCompressedMetaBlockHeader(is_last, length, storage_ix, storage);
973
974 tree = BROTLI_ALLOC(m, HuffmanTree, MAX_HUFFMAN_TREE_SIZE);
975 if (BROTLI_IS_OOM(m)) return;
976 InitBlockEncoder(&literal_enc, BROTLI_NUM_LITERAL_SYMBOLS,
977 mb->literal_split.num_types, mb->literal_split.types,
978 mb->literal_split.lengths, mb->literal_split.num_blocks);
979 InitBlockEncoder(&command_enc, BROTLI_NUM_COMMAND_SYMBOLS,
980 mb->command_split.num_types, mb->command_split.types,
981 mb->command_split.lengths, mb->command_split.num_blocks);
982 InitBlockEncoder(&distance_enc, num_effective_distance_symbols,
983 mb->distance_split.num_types, mb->distance_split.types,
984 mb->distance_split.lengths, mb->distance_split.num_blocks);
985
986 BuildAndStoreBlockSwitchEntropyCodes(&literal_enc, tree, storage_ix, storage);
987 BuildAndStoreBlockSwitchEntropyCodes(&command_enc, tree, storage_ix, storage);
988 BuildAndStoreBlockSwitchEntropyCodes(
989 &distance_enc, tree, storage_ix, storage);
990
991 BrotliWriteBits(2, dist->distance_postfix_bits, storage_ix, storage);
992 BrotliWriteBits(
993 4, dist->num_direct_distance_codes >> dist->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, BROTLI_NUM_LITERAL_SYMBOLS, tree,
1021 storage_ix, storage);
1022 if (BROTLI_IS_OOM(m)) return;
1023 BuildAndStoreEntropyCodesCommand(m, &command_enc, mb->command_histograms,
1024 mb->command_histograms_size, BROTLI_NUM_COMMAND_SYMBOLS, tree,
1025 storage_ix, storage);
1026 if (BROTLI_IS_OOM(m)) return;
1027 BuildAndStoreEntropyCodesDistance(m, &distance_enc, mb->distance_histograms,
1028 mb->distance_histograms_size, num_distance_symbols, tree,
1029 storage_ix, storage);
1030 if (BROTLI_IS_OOM(m)) return;
1031 BROTLI_FREE(m, tree);
1032
1033 for (i = 0; i < n_commands; ++i) {
1034 const Command cmd = commands[i];
1035 size_t cmd_code = cmd.cmd_prefix_;
1036 StoreSymbol(&command_enc, cmd_code, storage_ix, storage);
1037 StoreCommandExtra(&cmd, storage_ix, storage);
1038 if (mb->literal_context_map_size == 0) {
1039 size_t j;
1040 for (j = cmd.insert_len_; j != 0; --j) {
1041 StoreSymbol(&literal_enc, input[pos & mask], storage_ix, storage);
1042 ++pos;
1043 }
1044 } else {
1045 size_t j;
1046 for (j = cmd.insert_len_; j != 0; --j) {
1047 size_t context =
1048 BROTLI_CONTEXT(prev_byte, prev_byte2, literal_context_lut);
1049 uint8_t literal = input[pos & mask];
1050 StoreSymbolWithContext(&literal_enc, literal, context,
1051 mb->literal_context_map, storage_ix, storage,
1052 BROTLI_LITERAL_CONTEXT_BITS);
1053 prev_byte2 = prev_byte;
1054 prev_byte = literal;
1055 ++pos;
1056 }
1057 }
1058 pos += CommandCopyLen(&cmd);
1059 if (CommandCopyLen(&cmd)) {
1060 prev_byte2 = input[(pos - 2) & mask];
1061 prev_byte = input[(pos - 1) & mask];
1062 if (cmd.cmd_prefix_ >= 128) {
1063 size_t dist_code = cmd.dist_prefix_ & 0x3FF;
1064 uint32_t distnumextra = cmd.dist_prefix_ >> 10;
1065 uint64_t distextra = cmd.dist_extra_;
1066 if (mb->distance_context_map_size == 0) {
1067 StoreSymbol(&distance_enc, dist_code, storage_ix, storage);
1068 } else {
1069 size_t context = CommandDistanceContext(&cmd);
1070 StoreSymbolWithContext(&distance_enc, dist_code, context,
1071 mb->distance_context_map, storage_ix, storage,
1072 BROTLI_DISTANCE_CONTEXT_BITS);
1073 }
1074 BrotliWriteBits(distnumextra, distextra, storage_ix, storage);
1075 }
1076 }
1077 }
1078 CleanupBlockEncoder(m, &distance_enc);
1079 CleanupBlockEncoder(m, &command_enc);
1080 CleanupBlockEncoder(m, &literal_enc);
1081 if (is_last) {
1082 JumpToByteBoundary(storage_ix, storage);
1083 }
1084}
1085
1086static void BuildHistograms(const uint8_t* input,
1087 size_t start_pos,
1088 size_t mask,
1089 const Command* commands,
1090 size_t n_commands,
1091 HistogramLiteral* lit_histo,
1092 HistogramCommand* cmd_histo,
1093 HistogramDistance* dist_histo) {
1094 size_t pos = start_pos;
1095 size_t i;
1096 for (i = 0; i < n_commands; ++i) {
1097 const Command cmd = commands[i];
1098 size_t j;
1099 HistogramAddCommand(cmd_histo, cmd.cmd_prefix_);
1100 for (j = cmd.insert_len_; j != 0; --j) {
1101 HistogramAddLiteral(lit_histo, input[pos & mask]);
1102 ++pos;
1103 }
1104 pos += CommandCopyLen(&cmd);
1105 if (CommandCopyLen(&cmd) && cmd.cmd_prefix_ >= 128) {
1106 HistogramAddDistance(dist_histo, cmd.dist_prefix_ & 0x3FF);
1107 }
1108 }
1109}
1110
1111static void StoreDataWithHuffmanCodes(const uint8_t* input,
1112 size_t start_pos,
1113 size_t mask,
1114 const Command* commands,
1115 size_t n_commands,
1116 const uint8_t* lit_depth,
1117 const uint16_t* lit_bits,
1118 const uint8_t* cmd_depth,
1119 const uint16_t* cmd_bits,
1120 const uint8_t* dist_depth,
1121 const uint16_t* dist_bits,
1122 size_t* storage_ix,
1123 uint8_t* storage) {
1124 size_t pos = start_pos;
1125 size_t i;
1126 for (i = 0; i < n_commands; ++i) {
1127 const Command cmd = commands[i];
1128 const size_t cmd_code = cmd.cmd_prefix_;
1129 size_t j;
1130 BrotliWriteBits(
1131 cmd_depth[cmd_code], cmd_bits[cmd_code], storage_ix, storage);
1132 StoreCommandExtra(&cmd, storage_ix, storage);
1133 for (j = cmd.insert_len_; j != 0; --j) {
1134 const uint8_t literal = input[pos & mask];
1135 BrotliWriteBits(
1136 lit_depth[literal], lit_bits[literal], storage_ix, storage);
1137 ++pos;
1138 }
1139 pos += CommandCopyLen(&cmd);
1140 if (CommandCopyLen(&cmd) && cmd.cmd_prefix_ >= 128) {
1141 const size_t dist_code = cmd.dist_prefix_ & 0x3FF;
1142 const uint32_t distnumextra = cmd.dist_prefix_ >> 10;
1143 const uint32_t distextra = cmd.dist_extra_;
1144 BrotliWriteBits(dist_depth[dist_code], dist_bits[dist_code],
1145 storage_ix, storage);
1146 BrotliWriteBits(distnumextra, distextra, storage_ix, storage);
1147 }
1148 }
1149}
1150
1151void BrotliStoreMetaBlockTrivial(MemoryManager* m,
1152 const uint8_t* input, size_t start_pos, size_t length, size_t mask,
1153 BROTLI_BOOL is_last, const BrotliEncoderParams* params,
1154 const Command* commands, size_t n_commands,
1155 size_t* storage_ix, uint8_t* storage) {
1156 HistogramLiteral lit_histo;
1157 HistogramCommand cmd_histo;
1158 HistogramDistance dist_histo;
1159 uint8_t lit_depth[BROTLI_NUM_LITERAL_SYMBOLS];
1160 uint16_t lit_bits[BROTLI_NUM_LITERAL_SYMBOLS];
1161 uint8_t cmd_depth[BROTLI_NUM_COMMAND_SYMBOLS];
1162 uint16_t cmd_bits[BROTLI_NUM_COMMAND_SYMBOLS];
1163 uint8_t dist_depth[MAX_SIMPLE_DISTANCE_ALPHABET_SIZE];
1164 uint16_t dist_bits[MAX_SIMPLE_DISTANCE_ALPHABET_SIZE];
1165 HuffmanTree* tree;
1166 uint32_t num_distance_symbols = params->dist.alphabet_size;
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,
1182 BROTLI_NUM_LITERAL_SYMBOLS, tree,
1183 lit_depth, lit_bits,
1184 storage_ix, storage);
1185 BuildAndStoreHuffmanTree(cmd_histo.data_, BROTLI_NUM_COMMAND_SYMBOLS,
1186 BROTLI_NUM_COMMAND_SYMBOLS, tree,
1187 cmd_depth, cmd_bits,
1188 storage_ix, storage);
1189 BuildAndStoreHuffmanTree(dist_histo.data_, MAX_SIMPLE_DISTANCE_ALPHABET_SIZE,
1190 num_distance_symbols, tree,
1191 dist_depth, dist_bits,
1192 storage_ix, storage);
1193 BROTLI_FREE(m, tree);
1194 StoreDataWithHuffmanCodes(input, start_pos, mask, commands,
1195 n_commands, lit_depth, lit_bits,
1196 cmd_depth, cmd_bits,
1197 dist_depth, dist_bits,
1198 storage_ix, storage);
1199 if (is_last) {
1200 JumpToByteBoundary(storage_ix, storage);
1201 }
1202}
1203
1204void BrotliStoreMetaBlockFast(MemoryManager* m,
1205 const uint8_t* input, size_t start_pos, size_t length, size_t mask,
1206 BROTLI_BOOL is_last, const BrotliEncoderParams* params,
1207 const Command* commands, size_t n_commands,
1208 size_t* storage_ix, uint8_t* storage) {
1209 uint32_t num_distance_symbols = params->dist.alphabet_size;
1210 uint32_t distance_alphabet_bits =
1211 Log2FloorNonZero(num_distance_symbols - 1) + 1;
1212
1213 StoreCompressedMetaBlockHeader(is_last, length, storage_ix, storage);
1214
1215 BrotliWriteBits(13, 0, storage_ix, storage);
1216
1217 if (n_commands <= 128) {
1218 uint32_t histogram[BROTLI_NUM_LITERAL_SYMBOLS] = { 0 };
1219 size_t pos = start_pos;
1220 size_t num_literals = 0;
1221 size_t i;
1222 uint8_t lit_depth[BROTLI_NUM_LITERAL_SYMBOLS];
1223 uint16_t lit_bits[BROTLI_NUM_LITERAL_SYMBOLS];
1224 for (i = 0; i < n_commands; ++i) {
1225 const Command cmd = commands[i];
1226 size_t j;
1227 for (j = cmd.insert_len_; j != 0; --j) {
1228 ++histogram[input[pos & mask]];
1229 ++pos;
1230 }
1231 num_literals += cmd.insert_len_;
1232 pos += CommandCopyLen(&cmd);
1233 }
1234 BrotliBuildAndStoreHuffmanTreeFast(m, histogram, num_literals,
1235 /* max_bits = */ 8,
1236 lit_depth, lit_bits,
1237 storage_ix, storage);
1238 if (BROTLI_IS_OOM(m)) return;
1239 StoreStaticCommandHuffmanTree(storage_ix, storage);
1240 StoreStaticDistanceHuffmanTree(storage_ix, storage);
1241 StoreDataWithHuffmanCodes(input, start_pos, mask, commands,
1242 n_commands, lit_depth, lit_bits,
1243 kStaticCommandCodeDepth,
1244 kStaticCommandCodeBits,
1245 kStaticDistanceCodeDepth,
1246 kStaticDistanceCodeBits,
1247 storage_ix, storage);
1248 } else {
1249 HistogramLiteral lit_histo;
1250 HistogramCommand cmd_histo;
1251 HistogramDistance dist_histo;
1252 uint8_t lit_depth[BROTLI_NUM_LITERAL_SYMBOLS];
1253 uint16_t lit_bits[BROTLI_NUM_LITERAL_SYMBOLS];
1254 uint8_t cmd_depth[BROTLI_NUM_COMMAND_SYMBOLS];
1255 uint16_t cmd_bits[BROTLI_NUM_COMMAND_SYMBOLS];
1256 uint8_t dist_depth[MAX_SIMPLE_DISTANCE_ALPHABET_SIZE];
1257 uint16_t dist_bits[MAX_SIMPLE_DISTANCE_ALPHABET_SIZE];
1258 HistogramClearLiteral(&lit_histo);
1259 HistogramClearCommand(&cmd_histo);
1260 HistogramClearDistance(&dist_histo);
1261 BuildHistograms(input, start_pos, mask, commands, n_commands,
1262 &lit_histo, &cmd_histo, &dist_histo);
1263 BrotliBuildAndStoreHuffmanTreeFast(m, lit_histo.data_,
1264 lit_histo.total_count_,
1265 /* max_bits = */ 8,
1266 lit_depth, lit_bits,
1267 storage_ix, storage);
1268 if (BROTLI_IS_OOM(m)) return;
1269 BrotliBuildAndStoreHuffmanTreeFast(m, cmd_histo.data_,
1270 cmd_histo.total_count_,
1271 /* max_bits = */ 10,
1272 cmd_depth, cmd_bits,
1273 storage_ix, storage);
1274 if (BROTLI_IS_OOM(m)) return;
1275 BrotliBuildAndStoreHuffmanTreeFast(m, dist_histo.data_,
1276 dist_histo.total_count_,
1277 /* max_bits = */
1278 distance_alphabet_bits,
1279 dist_depth, dist_bits,
1280 storage_ix, storage);
1281 if (BROTLI_IS_OOM(m)) return;
1282 StoreDataWithHuffmanCodes(input, start_pos, mask, commands,
1283 n_commands, lit_depth, lit_bits,
1284 cmd_depth, cmd_bits,
1285 dist_depth, dist_bits,
1286 storage_ix, storage);
1287 }
1288
1289 if (is_last) {
1290 JumpToByteBoundary(storage_ix, storage);
1291 }
1292}
1293
1294/* This is for storing uncompressed blocks (simple raw storage of
1295 bytes-as-bytes). */
1296void BrotliStoreUncompressedMetaBlock(BROTLI_BOOL is_final_block,
1297 const uint8_t* BROTLI_RESTRICT input,
1298 size_t position, size_t mask,
1299 size_t len,
1300 size_t* BROTLI_RESTRICT storage_ix,
1301 uint8_t* BROTLI_RESTRICT storage) {
1302 size_t masked_pos = position & mask;
1303 BrotliStoreUncompressedMetaBlockHeader(len, storage_ix, storage);
1304 JumpToByteBoundary(storage_ix, storage);
1305
1306 if (masked_pos + len > mask + 1) {
1307 size_t len1 = mask + 1 - masked_pos;
1308 memcpy(&storage[*storage_ix >> 3], &input[masked_pos], len1);
1309 *storage_ix += len1 << 3;
1310 len -= len1;
1311 masked_pos = 0;
1312 }
1313 memcpy(&storage[*storage_ix >> 3], &input[masked_pos], len);
1314 *storage_ix += len << 3;
1315
1316 /* We need to clear the next 4 bytes to continue to be
1317 compatible with BrotliWriteBits. */
1318 BrotliWriteBitsPrepareStorage(*storage_ix, storage);
1319
1320 /* Since the uncompressed block itself may not be the final block, add an
1321 empty one after this. */
1322 if (is_final_block) {
1323 BrotliWriteBits(1, 1, storage_ix, storage); /* islast */
1324 BrotliWriteBits(1, 1, storage_ix, storage); /* isempty */
1325 JumpToByteBoundary(storage_ix, storage);
1326 }
1327}
1328
1329#if defined(__cplusplus) || defined(c_plusplus)
1330} /* extern "C" */
1331#endif
1332