GARbro-mirror/ArcFormats/Cmvs/HuffmanDecoder.cs
2017-11-27 12:47:15 +04:00

109 lines
3.3 KiB
C#

//! \file HuffmanDecoder.cs
//! \date 2017 Nov 27
//! \brief Custom Huffman decoder for CPZ archives.
//
// Copyright (C) 2017 by morkt
//
// Permission is hereby granted, free of charge, to any person obtaining a copy
// of this software and associated documentation files (the "Software"), to
// deal in the Software without restriction, including without limitation the
// rights to use, copy, modify, merge, publish, distribute, sublicense, and/or
// sell copies of the Software, and to permit persons to whom the Software is
// furnished to do so, subject to the following conditions:
//
// The above copyright notice and this permission notice shall be included in
// all copies or substantial portions of the Software.
//
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
// FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
// IN THE SOFTWARE.
//
using System.IO;
using GameRes.Utility;
namespace GameRes.Formats.Purple
{
internal sealed class HuffmanDecoder
{
byte[] m_input;
byte[] m_output;
int m_src;
int m_bits;
int m_bit_count;
ushort[] lhs = new ushort[512];
ushort[] rhs = new ushort[512];
ushort token = 256;
public HuffmanDecoder (byte[] src, int index, int length, byte[] dst)
{
m_input = src;
m_output = dst;
m_src = index;
m_bit_count = 0;
}
public byte[] Unpack ()
{
int dst = 0;
token = 256;
ushort root = CreateTree();
while (dst < m_output.Length)
{
ushort symbol = root;
while (symbol >= 0x100)
{
if (0 != GetBits (1))
symbol = rhs[symbol];
else
symbol = lhs[symbol];
}
m_output[dst++] = (byte)symbol;
}
return m_output;
}
ushort CreateTree()
{
if (0 != GetBits (1))
{
ushort v = token++;
if (v >= 511)
throw new InvalidDataException ("Invalid compressed data");
lhs[v] = CreateTree();
rhs[v] = CreateTree();
return v;
}
else
{
return (ushort)GetBits (8);
}
}
int GetBits (int count)
{
int bits = 0;
while (count --> 0)
{
if (0 == m_bit_count)
{
m_bits = LittleEndian.ToInt32 (m_input, m_src);
m_src += 4;
m_bit_count = 32;
}
bits = bits << 1 | (m_bits & 1);
m_bits >>= 1;
--m_bit_count;
}
return bits;
}
}
}