private void ReadMode0x81(Stream input, Stream output)
{
using (var br = new BitReader(input, BitOrder.LSBFirst, 1, ByteOrder.LittleEndian))
{
var initialByte = br.ReadBits <int>(8);
// 3 init holders
var rawValueMapping = new Tree();
rawValueMapping.Build(br, 8);
var indexValueMapping = new Tree();
indexValueMapping.Build(br, 6);
var dispIndexMapping = new Tree();
dispIndexMapping.Build(br, 5);
while (true)
{
var index = indexValueMapping.ReadValue(br);
if (index == 0)
{
if (initialByte < 3)
{
break;
}
var iVar4 = initialByte - 2;
if (output.Length <= iVar4)
{
break;
}
var length = output.Length - iVar4;
var position = 0;
do
{
length--;
output.Position = position;
var byte1 = output.ReadByte();
output.Position = position + iVar4;
var byte2 = output.ReadByte();
output.Position--;
output.WriteByte((byte)(byte1 + byte2));
position++;
} while (length != 0);
break;
}
if (index < 0x20)
{
// Match reading
// Max displacement 0x8000; Min displacement 1
// Max length 0x102; Min length 1
var counter = _counters[index];
if (_counterBitReads[index] != 0)
{
counter += br.ReadBits <int>(_counterBitReads[index]);
}
var dispIndex = dispIndexMapping.ReadValue(br);
var displacement = _dispRanges[dispIndex];
if (_dispBitReads[dispIndex] != 0)
{
displacement += br.ReadBits <int>(_dispBitReads[dispIndex]);
}
if (counter == 0)
{
continue;
}
var bufferIndex = _windowBufferOffset + _windowBuffer.Length - displacement;
for (int i = 0; i < counter; i++)
{
var next = _windowBuffer[bufferIndex++ % _windowBuffer.Length];
output.WriteByte(next);
_windowBuffer[_windowBufferOffset] = next;
_windowBufferOffset = (_windowBufferOffset + 1) % _windowBuffer.Length;
}
}
else
{
// Raw data reading
index -= 0x20;
var counter = _counters[index];
if (_counterBitReads[index] != 0)
{
counter += br.ReadBits <int>(_counterBitReads[index]);
}
if (counter == 0)
{
continue;
}
for (int i = 0; i < counter; i++)
{
var rawValue = (byte)rawValueMapping.ReadValue(br);
output.WriteByte(rawValue);
_windowBuffer[_windowBufferOffset] = rawValue;
_windowBufferOffset = (_windowBufferOffset + 1) % _windowBuffer.Length;
}
}
}
}
}
public void Build(BitReader br, int valueBitCount)
{
_root = new Node();
ReadNode(br, _root, valueBitCount);
}