| /* |
| Copyright 2011 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. |
| |
| Author: lode.vandevenne@gmail.com (Lode Vandevenne) |
| Author: jyrki.alakuijala@gmail.com (Jyrki Alakuijala) |
| */ |
| |
| /* |
| Utilities for creating and using Huffman trees. |
| */ |
| |
| #ifndef ZOPFLI_TREE_H_ |
| #define ZOPFLI_TREE_H_ |
| |
| #include <string.h> |
| |
| /* |
| Calculates the bitlengths for the Huffman tree, based on the counts of each |
| symbol. |
| */ |
| void ZopfliCalculateBitLengths(const size_t* count, size_t n, int maxbits, |
| unsigned *bitlengths); |
| |
| /* |
| Converts a series of Huffman tree bitlengths, to the bit values of the symbols. |
| */ |
| void ZopfliLengthsToSymbols(const unsigned* lengths, size_t n, unsigned maxbits, |
| unsigned* symbols); |
| |
| /* |
| Calculates the entropy of each symbol, based on the counts of each symbol. The |
| result is similar to the result of ZopfliCalculateBitLengths, but with the |
| actual theoritical bit lengths according to the entropy. Since the resulting |
| values are fractional, they cannot be used to encode the tree specified by |
| DEFLATE. |
| */ |
| void ZopfliCalculateEntropy(const size_t* count, size_t n, double* bitlengths); |
| |
| #endif /* ZOPFLI_TREE_H_ */ |