123 lines
3.6 KiB
C++
123 lines
3.6 KiB
C++
/*
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Huffman decoder.
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The code in this file is based on TheUnarchiver.
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See README.md and docs/licenses/TheUnarchiver.txt for more information.
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Copyright (C) 2019, Guillaume Gonnet
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This program is free software: you can redistribute it and/or modify it under
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the terms of the GNU General Public License as published by the Free Software
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Foundation, either version 3 of the License, or (at your option) any later
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version.
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This program is distributed in the hope that it will be useful, but WITHOUT ANY
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WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A
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PARTICULAR PURPOSE. See the GNU General Public License for more details.
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You should have received a copy of the GNU General Public License along with
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this program. If not, see <https://www.gnu.org/licenses/>.
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*/
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#pragma once
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#include "utils/bit_reader.h"
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#include <vector>
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#include <memory>
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namespace maconv {
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namespace stuffit {
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// A node in the Huffman tree.
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struct HuffmanTreeNode {
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int branches[2];
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};
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struct HuffmanTableEntry {
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uint32_t length;
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int32_t value;
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};
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// Huffman code decoder.
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struct HuffmanDecoder {
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// Copy an Huffman decoder.
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HuffmanDecoder &operator=(const HuffmanDecoder &);
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// Initialize the decoder.
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void Initialize();
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void Initialize(const int *lengths, int numsymbols, int maxcodelength, bool zeros);
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// Add a new value in the decoder (high bit first).
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void AddValue(int value, uint32_t code, int length);
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void AddValue(int value, uint32_t code, int length, int repeat_pos);
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// Add a new value in the decoder (low bit first).
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void AddValueLF(int value, uint32_t code, int length);
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void AddValueLF(int value, uint32_t code, int length, int repeat_pos);
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// Get the next symbol from a bit reader.
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int NextSymbol(utils::BitReader &input);
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// Make the search table.
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void MakeTable(bool is_LE);
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protected:
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// Get a pointer on a node.
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HuffmanTreeNode *NodePtr(int node) { return &tree[node]; }
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// Get/set node ID on branch |bit| of |node|.
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int Branch(int node, int bit) { return NodePtr(node)->branches[bit]; }
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void SetBranch(int node, int bit, int next) { NodePtr(node)->branches[bit] = next; }
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// Get/set left branch of |node|.
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int LeftBranch(int node) { return Branch(node, 0); }
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void SetLeftBranch(int node, int next) { SetBranch(node, 0, next); }
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// Get/set right branch of |node|.
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int RightBranch(int node) { return Branch(node, 1); }
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void SetRightBranch(int node, int next) { SetBranch(node, 1, next); }
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// Get/set leaf value.
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int LeafValue(int node) { return LeftBranch(node); }
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void SetLeafValue(int node, int v) { SetLeftBranch(node, v); SetRightBranch(node, v); }
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// Set/get whether a node is empty or not.
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void SetEmptyNode(int node) { SetLeftBranch(node, -1); SetRightBranch(node, -2); }
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bool IsEmptyNode(int node) { return LeftBranch(node) == -1 && RightBranch(node) == -2; }
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// Get information on a node.
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bool IsInvalidNode(int node) { return node < 0; }
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bool IsOpenBranch(int node, int bit) { return IsInvalidNode(Branch(node, bit)); }
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bool IsLeafNode(int node) { return LeftBranch(node) == RightBranch(node); }
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// Create a new node.
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int NewNode() { tree.push_back({0}); SetEmptyNode(tree.size()-1);
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return tree.size()-1; }
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// Make search table.
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void MakeTableRecursLE(int node, HuffmanTableEntry *table, int depth);
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void MakeTableRecursBE(int node, HuffmanTableEntry *table, int depth);
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std::vector<HuffmanTreeNode> tree;
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int num_entries, min_length, max_length;
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int table_size;
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std::unique_ptr<HuffmanTableEntry[]> table;
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};
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} // namespace stuffit
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} // namespace maconv
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