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
BlockLengthPrefixCode(uint32_t len)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
GetBlockLengthPrefixCode(uint32_t len,size_t * code,uint32_t * n_extra,uint32_t * extra)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
InitBlockTypeCodeCalculator(BlockTypeCodeCalculator * self)71 static void InitBlockTypeCodeCalculator(BlockTypeCodeCalculator* self) {
72 self->last_type = 1;
73 self->second_last_type = 0;
74 }
75
NextBlockTypeCode(BlockTypeCodeCalculator * calculator,uint8_t type)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) */
BrotliEncodeMlen(size_t length,uint64_t * bits,size_t * numbits,uint64_t * nibblesbits)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
StoreCommandExtra(const Command * cmd,size_t * storage_ix,uint8_t * storage)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. */
StoreVarLenUint8(size_t n,size_t * storage_ix,uint8_t * storage)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) */
StoreCompressedMetaBlockHeader(BROTLI_BOOL is_final_block,size_t length,size_t * storage_ix,uint8_t * storage)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) */
BrotliStoreUncompressedMetaBlockHeader(size_t length,size_t * storage_ix,uint8_t * storage)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
BrotliStoreHuffmanTreeOfHuffmanTreeToBitMask(const int num_codes,const uint8_t * code_length_bitdepth,size_t * storage_ix,uint8_t * storage)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
BrotliStoreHuffmanTreeToBitMask(const size_t huffman_tree_size,const uint8_t * huffman_tree,const uint8_t * huffman_tree_extra_bits,const uint8_t * code_length_bitdepth,const uint16_t * code_length_bitdepth_symbols,size_t * BROTLI_RESTRICT storage_ix,uint8_t * BROTLI_RESTRICT storage)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
StoreSimpleHuffmanTree(const uint8_t * depths,size_t symbols[4],size_t num_symbols,size_t max_bits,size_t * storage_ix,uint8_t * storage)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 */
BrotliStoreHuffmanTree(const uint8_t * depths,size_t num,HuffmanTree * tree,size_t * storage_ix,uint8_t * storage)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. */
BuildAndStoreHuffmanTree(const uint32_t * histogram,const size_t length,HuffmanTree * tree,uint8_t * depth,uint16_t * bits,size_t * storage_ix,uint8_t * storage)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
SortHuffmanTree(const HuffmanTree * v0,const HuffmanTree * v1)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
BrotliBuildAndStoreHuffmanTreeFast(MemoryManager * m,const uint32_t * histogram,const size_t histogram_total,const size_t max_bits,uint8_t * depth,uint16_t * bits,size_t * storage_ix,uint8_t * storage)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
IndexOf(const uint8_t * v,size_t v_size,uint8_t value)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
MoveToFront(uint8_t * v,size_t index)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
MoveToFrontTransform(const uint32_t * BROTLI_RESTRICT v_in,const size_t v_size,uint32_t * v_out)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. */
RunLengthCodeZeros(const size_t in_size,uint32_t * BROTLI_RESTRICT v,size_t * BROTLI_RESTRICT out_size,uint32_t * BROTLI_RESTRICT max_run_length_prefix)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
EncodeContextMap(MemoryManager * m,const uint32_t * context_map,size_t context_map_size,size_t num_clusters,HuffmanTree * tree,size_t * storage_ix,uint8_t * storage)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. */
StoreBlockSwitch(BlockSplitCode * code,const uint32_t block_len,const uint8_t block_type,BROTLI_BOOL is_first_block,size_t * storage_ix,uint8_t * storage)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. */
BuildAndStoreBlockSplitCode(const uint8_t * types,const uint32_t * lengths,const size_t num_blocks,const size_t num_types,HuffmanTree * tree,BlockSplitCode * code,size_t * storage_ix,uint8_t * storage)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. */
StoreTrivialContextMap(size_t num_types,size_t context_bits,HuffmanTree * tree,size_t * storage_ix,uint8_t * storage)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
InitBlockEncoder(BlockEncoder * self,size_t alphabet_size,size_t num_block_types,const uint8_t * block_types,const uint32_t * block_lengths,const size_t num_blocks)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
CleanupBlockEncoder(MemoryManager * m,BlockEncoder * self)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. */
BuildAndStoreBlockSwitchEntropyCodes(BlockEncoder * self,HuffmanTree * tree,size_t * storage_ix,uint8_t * storage)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. */
StoreSymbol(BlockEncoder * self,size_t symbol,size_t * storage_ix,uint8_t * storage)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. */
StoreSymbolWithContext(BlockEncoder * self,size_t symbol,size_t context,const uint32_t * context_map,size_t * storage_ix,uint8_t * storage,const size_t context_bits)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
JumpToByteBoundary(size_t * storage_ix,uint8_t * storage)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
BrotliStoreMetaBlock(MemoryManager * m,const uint8_t * input,size_t start_pos,size_t length,size_t mask,uint8_t prev_byte,uint8_t prev_byte2,BROTLI_BOOL is_last,uint32_t num_direct_distance_codes,uint32_t distance_postfix_bits,ContextType literal_context_mode,const Command * commands,size_t n_commands,const MetaBlockSplit * mb,size_t * storage_ix,uint8_t * storage)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
BuildHistograms(const uint8_t * input,size_t start_pos,size_t mask,const Command * commands,size_t n_commands,HistogramLiteral * lit_histo,HistogramCommand * cmd_histo,HistogramDistance * dist_histo)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
StoreDataWithHuffmanCodes(const uint8_t * input,size_t start_pos,size_t mask,const Command * commands,size_t n_commands,const uint8_t * lit_depth,const uint16_t * lit_bits,const uint8_t * cmd_depth,const uint16_t * cmd_bits,const uint8_t * dist_depth,const uint16_t * dist_bits,size_t * storage_ix,uint8_t * storage)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
BrotliStoreMetaBlockTrivial(MemoryManager * m,const uint8_t * input,size_t start_pos,size_t length,size_t mask,BROTLI_BOOL is_last,const Command * commands,size_t n_commands,size_t * storage_ix,uint8_t * storage)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
BrotliStoreMetaBlockFast(MemoryManager * m,const uint8_t * input,size_t start_pos,size_t length,size_t mask,BROTLI_BOOL is_last,const Command * commands,size_t n_commands,size_t * storage_ix,uint8_t * storage)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). */
BrotliStoreUncompressedMetaBlock(BROTLI_BOOL is_final_block,const uint8_t * BROTLI_RESTRICT input,size_t position,size_t mask,size_t len,size_t * BROTLI_RESTRICT storage_ix,uint8_t * BROTLI_RESTRICT storage)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 #if defined(__cplusplus) || defined(c_plusplus)
1329 } /* extern "C" */
1330 #endif
1331