Hash :
4b2b2d4f
Author :
Date :
2019-04-12T13:57:42
Update (#749)
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
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/* Copyright 2013 Google Inc. All Rights Reserved.
Distributed under MIT license.
See file LICENSE for detail or copy at https://opensource.org/licenses/MIT
*/
/* Function to find backward reference copies. */
#include "./backward_references.h"
#include "../common/constants.h"
#include "../common/context.h"
#include "../common/dictionary.h"
#include "../common/platform.h"
#include <brotli/types.h>
#include "./command.h"
#include "./dictionary_hash.h"
#include "./memory.h"
#include "./quality.h"
#if defined(__cplusplus) || defined(c_plusplus)
extern "C" {
#endif
static BROTLI_INLINE size_t ComputeDistanceCode(size_t distance,
size_t max_distance,
const int* dist_cache) {
if (distance <= max_distance) {
size_t distance_plus_3 = distance + 3;
size_t offset0 = distance_plus_3 - (size_t)dist_cache[0];
size_t offset1 = distance_plus_3 - (size_t)dist_cache[1];
if (distance == (size_t)dist_cache[0]) {
return 0;
} else if (distance == (size_t)dist_cache[1]) {
return 1;
} else if (offset0 < 7) {
return (0x9750468 >> (4 * offset0)) & 0xF;
} else if (offset1 < 7) {
return (0xFDB1ACE >> (4 * offset1)) & 0xF;
} else if (distance == (size_t)dist_cache[2]) {
return 2;
} else if (distance == (size_t)dist_cache[3]) {
return 3;
}
}
return distance + BROTLI_NUM_DISTANCE_SHORT_CODES - 1;
}
#define EXPAND_CAT(a, b) CAT(a, b)
#define CAT(a, b) a ## b
#define FN(X) EXPAND_CAT(X, HASHER())
#define EXPORT_FN(X) EXPAND_CAT(X, EXPAND_CAT(PREFIX(), HASHER()))
#define PREFIX() N
#define HASHER() H2
/* NOLINTNEXTLINE(build/include) */
#include "./backward_references_inc.h"
#undef HASHER
#define HASHER() H3
/* NOLINTNEXTLINE(build/include) */
#include "./backward_references_inc.h"
#undef HASHER
#define HASHER() H4
/* NOLINTNEXTLINE(build/include) */
#include "./backward_references_inc.h"
#undef HASHER
#define HASHER() H5
/* NOLINTNEXTLINE(build/include) */
#include "./backward_references_inc.h"
#undef HASHER
#define HASHER() H6
/* NOLINTNEXTLINE(build/include) */
#include "./backward_references_inc.h"
#undef HASHER
#define HASHER() H40
/* NOLINTNEXTLINE(build/include) */
#include "./backward_references_inc.h"
#undef HASHER
#define HASHER() H41
/* NOLINTNEXTLINE(build/include) */
#include "./backward_references_inc.h"
#undef HASHER
#define HASHER() H42
/* NOLINTNEXTLINE(build/include) */
#include "./backward_references_inc.h"
#undef HASHER
#define HASHER() H54
/* NOLINTNEXTLINE(build/include) */
#include "./backward_references_inc.h"
#undef HASHER
#define HASHER() H35
/* NOLINTNEXTLINE(build/include) */
#include "./backward_references_inc.h"
#undef HASHER
#define HASHER() H55
/* NOLINTNEXTLINE(build/include) */
#include "./backward_references_inc.h"
#undef HASHER
#define HASHER() H65
/* NOLINTNEXTLINE(build/include) */
#include "./backward_references_inc.h"
#undef HASHER
#undef PREFIX
#undef EXPORT_FN
#undef FN
#undef CAT
#undef EXPAND_CAT
void BrotliCreateBackwardReferences(size_t num_bytes,
size_t position, const uint8_t* ringbuffer, size_t ringbuffer_mask,
ContextLut literal_context_lut, const BrotliEncoderParams* params,
Hasher* hasher, int* dist_cache, size_t* last_insert_len,
Command* commands, size_t* num_commands, size_t* num_literals) {
switch (params->hasher.type) {
#define CASE_(N) \
case N: \
CreateBackwardReferencesNH ## N(num_bytes, \
position, ringbuffer, ringbuffer_mask, \
literal_context_lut, params, hasher, dist_cache, \
last_insert_len, commands, num_commands, num_literals); \
return;
FOR_GENERIC_HASHERS(CASE_)
#undef CASE_
default:
break;
}
}
#if defined(__cplusplus) || defined(c_plusplus)
} /* extern "C" */
#endif