// Copyright (c) the JPEG XL Project Authors. All rights reserved.

//

// Use of this source code is governed by a BSD-style

// license that can be found in the LICENSE file.

#ifndef LIB_JXL_DEC_HUFFMAN_H_

#define LIB_JXL_DEC_HUFFMAN_H_

#include <cstddef>

#include <cstdint>

#include <vector>

#include "lib/jxl/base/compiler_specific.h"

#include "lib/jxl/dec_bit_reader.h"

#include "lib/jxl/huffman_table.h"

namespace jxl {

static constexpr size_t kHuffmanTableBits = 8u;

struct HuffmanDecodingData {

  // Decodes the Huffman code lengths from the bit-stream and fills in the

  // pre-allocated table with the corresponding 2-level Huffman decoding table.

  // Returns false if the Huffman code lengths can not be decoded.

  bool ReadFromBitStream(size_t alphabet_size, BitReader* br);

  // Decodes the next Huffman coded symbol from the bit-stream.

  JXL_INLINE uint16_t ReadSymbol(BitReader* br) const {

    size_t n_bits;

    const HuffmanCode* table = table_.data();

    table += br->PeekBits(kHuffmanTableBits);

    n_bits = table->bits;

    if (n_bits > kHuffmanTableBits) {

      br->Consume(kHuffmanTableBits);

      n_bits -= kHuffmanTableBits;

      table += table->value;

      table += br->PeekBits(n_bits);

    }

    br->Consume(table->bits);

    return table->value;

  }

  std::vector<HuffmanCode> table_;

};

}  // namespace jxl

#endif  // LIB_JXL_DEC_HUFFMAN_H_