Index: third_party/brotli/enc/quality.h |
diff --git a/third_party/brotli/enc/quality.h b/third_party/brotli/enc/quality.h |
new file mode 100644 |
index 0000000000000000000000000000000000000000..6dade07233f855d1e16c8600a0552e037b3bed23 |
--- /dev/null |
+++ b/third_party/brotli/enc/quality.h |
@@ -0,0 +1,134 @@ |
+/* Copyright 2016 Google Inc. All Rights Reserved. |
+ |
+ Distributed under MIT license. |
+ See file LICENSE for detail or copy at https://opensource.org/licenses/MIT |
+*/ |
+ |
+/* Constants and formulas that affect speed-ratio trade-offs and thus define |
+ quality levels. */ |
+ |
+#ifndef BROTLI_ENC_QUALITY_H_ |
+#define BROTLI_ENC_QUALITY_H_ |
+ |
+#include <brotli/encode.h> |
+ |
+#define FAST_ONE_PASS_COMPRESSION_QUALITY 0 |
+#define FAST_TWO_PASS_COMPRESSION_QUALITY 1 |
+#define ZOPFLIFICATION_QUALITY 10 |
+#define HQ_ZOPFLIFICATION_QUALITY 11 |
+ |
+#define MAX_QUALITY_FOR_STATIC_ENRTOPY_CODES 2 |
+#define MIN_QUALITY_FOR_BLOCK_SPLIT 4 |
+#define MIN_QUALITY_FOR_OPTIMIZE_HISTOGRAMS 4 |
+#define MIN_QUALITY_FOR_EXTENSIVE_REFERENCE_SEARCH 5 |
+#define MIN_QUALITY_FOR_CONTEXT_MODELING 5 |
+#define MIN_QUALITY_FOR_HQ_CONTEXT_MODELING 7 |
+#define MIN_QUALITY_FOR_HQ_BLOCK_SPLITTING 10 |
+/* Only for "font" mode. */ |
+#define MIN_QUALITY_FOR_RECOMPUTE_DISTANCE_PREFIXES 10 |
+ |
+/* For quality below MIN_QUALITY_FOR_BLOCK_SPLIT there is no block splitting, |
+ so we buffer at most this much literals and commands. */ |
+#define MAX_NUM_DELAYED_SYMBOLS 0x2fff |
+ |
+/* Encoding parameters */ |
+typedef struct BrotliEncoderParams { |
+ BrotliEncoderMode mode; |
+ int quality; |
+ int lgwin; |
+ int lgblock; |
+} BrotliEncoderParams; |
+ |
+/* Returns hash-table size for quality levels 0 and 1. */ |
+static BROTLI_INLINE size_t MaxHashTableSize(int quality) { |
+ return quality == FAST_ONE_PASS_COMPRESSION_QUALITY ? 1 << 15 : 1 << 17; |
+} |
+ |
+/* The maximum length for which the zopflification uses distinct distances. */ |
+#define MAX_ZOPFLI_LEN_QUALITY_10 150 |
+#define MAX_ZOPFLI_LEN_QUALITY_11 325 |
+ |
+/* Do not thoroughly search when a long copy is found. */ |
+#define BROTLI_LONG_COPY_QUICK_STEP 16384 |
+ |
+static BROTLI_INLINE size_t MaxZopfliLen(const BrotliEncoderParams* params) { |
+ return params->quality <= 10 ? |
+ MAX_ZOPFLI_LEN_QUALITY_10 : |
+ MAX_ZOPFLI_LEN_QUALITY_11; |
+} |
+ |
+/* Number of best candidates to evaluate to expand Zopfli chain. */ |
+static BROTLI_INLINE size_t MaxZopfliCandidates( |
+ const BrotliEncoderParams* params) { |
+ return params->quality <= 10 ? 1 : 5; |
+} |
+ |
+static BROTLI_INLINE void SanitizeParams(BrotliEncoderParams* params) { |
+ params->quality = BROTLI_MIN(int, BROTLI_MAX_QUALITY, |
+ BROTLI_MAX(int, BROTLI_MIN_QUALITY, params->quality)); |
+ if (params->lgwin < BROTLI_MIN_WINDOW_BITS) { |
+ params->lgwin = BROTLI_MIN_WINDOW_BITS; |
+ } else if (params->lgwin > BROTLI_MAX_WINDOW_BITS) { |
+ params->lgwin = BROTLI_MAX_WINDOW_BITS; |
+ } |
+} |
+ |
+/* Returns optimized lg_block value. */ |
+static BROTLI_INLINE int ComputeLgBlock(const BrotliEncoderParams* params) { |
+ int lgblock = params->lgblock; |
+ if (params->quality == FAST_ONE_PASS_COMPRESSION_QUALITY || |
+ params->quality == FAST_TWO_PASS_COMPRESSION_QUALITY) { |
+ lgblock = params->lgwin; |
+ } else if (params->quality < MIN_QUALITY_FOR_BLOCK_SPLIT) { |
+ lgblock = 14; |
+ } else if (lgblock == 0) { |
+ lgblock = 16; |
+ if (params->quality >= 9 && params->lgwin > lgblock) { |
+ lgblock = BROTLI_MIN(int, 18, params->lgwin); |
+ } |
+ } else { |
+ lgblock = BROTLI_MIN(int, BROTLI_MAX_INPUT_BLOCK_BITS, |
+ BROTLI_MAX(int, BROTLI_MIN_INPUT_BLOCK_BITS, lgblock)); |
+ } |
+ return lgblock; |
+} |
+ |
+/* Returns log2 of the size of main ring buffer area. |
+ Allocate at least lgwin + 1 bits for the ring buffer so that the newly |
+ added block fits there completely and we still get lgwin bits and at least |
+ read_block_size_bits + 1 bits because the copy tail length needs to be |
+ smaller than ring-buffer size. */ |
+static BROTLI_INLINE int ComputeRbBits(const BrotliEncoderParams* params) { |
+ return 1 + BROTLI_MAX(int, params->lgwin, params->lgblock); |
+} |
+ |
+static BROTLI_INLINE size_t MaxMetablockSize( |
+ const BrotliEncoderParams* params) { |
+ int bits = |
+ BROTLI_MIN(int, ComputeRbBits(params), BROTLI_MAX_INPUT_BLOCK_BITS); |
+ return (size_t)1 << bits; |
+} |
+ |
+/* When searching for backward references and have not seen matches for a long |
+ time, we can skip some match lookups. Unsuccessful match lookups are very |
+ expensive and this kind of a heuristic speeds up compression quite a lot. |
+ At first 8 byte strides are taken and every second byte is put to hasher. |
+ After 4x more literals stride by 16 bytes, every put 4-th byte to hasher. |
+ Applied only to qualities 2 to 9. */ |
+static BROTLI_INLINE size_t LiteralSpreeLengthForSparseSearch( |
+ const BrotliEncoderParams* params) { |
+ return params->quality < 9 ? 64 : 512; |
+} |
+ |
+static BROTLI_INLINE int ChooseHasher(const BrotliEncoderParams* params) { |
+ if (params->quality > 9) { |
+ return 10; |
+ } else if (params->quality < 5) { |
+ return params->quality; |
+ } else if (params->lgwin <= 16) { |
+ return params->quality < 7 ? 40 : params->quality < 9 ? 41 : 42; |
+ } |
+ return params->quality; |
+} |
+ |
+#endif /* BROTLI_ENC_QUALITY_H_ */ |