mirror of
https://github.com/google/brotli.git
synced 2024-11-25 21:10:05 +00:00
4b2b2d4f83
Update:
* Bazel: fix MSVC configuration
* C: common: extended documentation and helpers around distance codes
* C: common: enable BROTLI_DCHECK in "debug" builds
* C: common: fix implicit trailing zero in `kPrefixSuffix`
* C: dec: fix possible bit reader discharge for "large-window" mode
* C: dec: simplify distance decoding via lookup table
* C: dec: reuse decoder state members memory via union with lookup table
* C: dec: add decoder state diagram
* C: enc: clarify access to static dictionary
* C: enc: improve static dictionary hash
* C: enc: add "stream offset" parameter for parallel encoding
* C: enc: reorganize hasher; now Q2-Q3 require exactly 256KiB
to avoid global TCMalloc lock
* C: enc: fix rare access to uninitialized data in ring-buffer
* C: enc: reorganize logging / checks in `write_bits.h`
* Java: dec: add "large-window" support
* Java: dec: improve speed
* Java: dec: debug and 32-bit mode are now activated via system properties
* Java: dec: demystify some state variables (use better names)
* Dictionary generator: add single input mode
* Java: dec: modernize tests
* Bazel: js: pick working commit for closure rules
146 lines
3.9 KiB
C
146 lines
3.9 KiB
C
/* Copyright 2013 Google Inc. All Rights Reserved.
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Distributed under MIT license.
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See file LICENSE for detail or copy at https://opensource.org/licenses/MIT
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*/
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/* Function to find backward reference copies. */
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#include "./backward_references.h"
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#include "../common/constants.h"
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#include "../common/context.h"
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#include "../common/dictionary.h"
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#include "../common/platform.h"
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#include <brotli/types.h>
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#include "./command.h"
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#include "./dictionary_hash.h"
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#include "./memory.h"
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#include "./quality.h"
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#if defined(__cplusplus) || defined(c_plusplus)
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extern "C" {
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#endif
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static BROTLI_INLINE size_t ComputeDistanceCode(size_t distance,
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size_t max_distance,
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const int* dist_cache) {
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if (distance <= max_distance) {
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size_t distance_plus_3 = distance + 3;
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size_t offset0 = distance_plus_3 - (size_t)dist_cache[0];
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size_t offset1 = distance_plus_3 - (size_t)dist_cache[1];
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if (distance == (size_t)dist_cache[0]) {
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return 0;
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} else if (distance == (size_t)dist_cache[1]) {
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return 1;
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} else if (offset0 < 7) {
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return (0x9750468 >> (4 * offset0)) & 0xF;
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} else if (offset1 < 7) {
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return (0xFDB1ACE >> (4 * offset1)) & 0xF;
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} else if (distance == (size_t)dist_cache[2]) {
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return 2;
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} else if (distance == (size_t)dist_cache[3]) {
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return 3;
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}
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}
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return distance + BROTLI_NUM_DISTANCE_SHORT_CODES - 1;
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}
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#define EXPAND_CAT(a, b) CAT(a, b)
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#define CAT(a, b) a ## b
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#define FN(X) EXPAND_CAT(X, HASHER())
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#define EXPORT_FN(X) EXPAND_CAT(X, EXPAND_CAT(PREFIX(), HASHER()))
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#define PREFIX() N
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#define HASHER() H2
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/* NOLINTNEXTLINE(build/include) */
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#include "./backward_references_inc.h"
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#undef HASHER
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#define HASHER() H3
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/* NOLINTNEXTLINE(build/include) */
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#include "./backward_references_inc.h"
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#undef HASHER
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#define HASHER() H4
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/* NOLINTNEXTLINE(build/include) */
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#include "./backward_references_inc.h"
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#undef HASHER
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#define HASHER() H5
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/* NOLINTNEXTLINE(build/include) */
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#include "./backward_references_inc.h"
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#undef HASHER
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#define HASHER() H6
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/* NOLINTNEXTLINE(build/include) */
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#include "./backward_references_inc.h"
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#undef HASHER
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#define HASHER() H40
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/* NOLINTNEXTLINE(build/include) */
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#include "./backward_references_inc.h"
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#undef HASHER
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#define HASHER() H41
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/* NOLINTNEXTLINE(build/include) */
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#include "./backward_references_inc.h"
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#undef HASHER
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#define HASHER() H42
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/* NOLINTNEXTLINE(build/include) */
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#include "./backward_references_inc.h"
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#undef HASHER
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#define HASHER() H54
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/* NOLINTNEXTLINE(build/include) */
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#include "./backward_references_inc.h"
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#undef HASHER
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#define HASHER() H35
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/* NOLINTNEXTLINE(build/include) */
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#include "./backward_references_inc.h"
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#undef HASHER
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#define HASHER() H55
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/* NOLINTNEXTLINE(build/include) */
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#include "./backward_references_inc.h"
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#undef HASHER
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#define HASHER() H65
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/* NOLINTNEXTLINE(build/include) */
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#include "./backward_references_inc.h"
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#undef HASHER
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#undef PREFIX
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#undef EXPORT_FN
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#undef FN
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#undef CAT
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#undef EXPAND_CAT
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void BrotliCreateBackwardReferences(size_t num_bytes,
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size_t position, const uint8_t* ringbuffer, size_t ringbuffer_mask,
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ContextLut literal_context_lut, const BrotliEncoderParams* params,
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Hasher* hasher, int* dist_cache, size_t* last_insert_len,
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Command* commands, size_t* num_commands, size_t* num_literals) {
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switch (params->hasher.type) {
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#define CASE_(N) \
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case N: \
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CreateBackwardReferencesNH ## N(num_bytes, \
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position, ringbuffer, ringbuffer_mask, \
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literal_context_lut, params, hasher, dist_cache, \
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last_insert_len, commands, num_commands, num_literals); \
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return;
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FOR_GENERIC_HASHERS(CASE_)
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#undef CASE_
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default:
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break;
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}
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}
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#if defined(__cplusplus) || defined(c_plusplus)
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} /* extern "C" */
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#endif
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