brotli/enc/static_dict.h
Zoltan Szabadka 66098830a2 Use a static hash table to look up dictionary words and transforms.
This is used for quality 11, for qualities <= 9 we already
have a simpler hash table.

The static data size is 252 kB, and this removes the
need to initialize a huge hash map at startup, which was
the reason why transforms had to be disabled by default.
In comparison, the static dictionary itself is 120 kB.
This supports every transform, except the kOmitFirstN.
2015-06-12 16:45:17 +02:00

40 lines
1.4 KiB
C++

// Copyright 2013 Google Inc. All Rights Reserved.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
//
// Class to model the static dictionary.
#ifndef BROTLI_ENC_STATIC_DICT_H_
#define BROTLI_ENC_STATIC_DICT_H_
#include <stdint.h>
namespace brotli {
static const int kMaxDictionaryMatchLen = 37;
static const int kInvalidMatch = 0xfffffff;
// Matches data against static dictionary words, and for each length l,
// for which a match is found, updates matches[l] to be the minimum possible
// (distance << 5) + len_code.
// Prerequisites:
// matches array is at least kMaxDictionaryMatchLen + 1 long
// all elements are initialized to kInvalidMatch
bool FindAllStaticDictionaryMatches(const uint8_t* data,
int min_length,
int* matches);
} // namespace brotli
#endif // BROTLI_ENC_STATIC_DICT_H_