public List <int> Unpack(List <byte> packedBytes)
{
List <int> codeStream = new List <int>();
List <byte> tempPackedBytes = new List <byte>();
tempPackedBytes.AddRange(packedBytes);
List <bool> bitStream = new List <bool>();
int currentCodeWidth = LzwMinimumCodeSize + 1;
int codeWidthIncreaseThreshold = (int)Math.Pow(2, currentCodeWidth) - 1;
for (int i = 0; i < tempPackedBytes.Count; i++)
{
tempPackedBytes[i] = tempPackedBytes[i].ReverseByte(); // big endian
List <bool> bits = GlobalUtilities.ConvertByteToBits(tempPackedBytes[i], 8);
bits.Reverse();
bitStream.AddRange(bits);
}
for (int i = 0; i < bitStream.Count; i += 0)
{
if (codeStream.Count >= codeWidthIncreaseThreshold)
{
currentCodeWidth++;
codeWidthIncreaseThreshold = (int)Math.Pow(2, currentCodeWidth) - 1;
}
if (i + currentCodeWidth < bitStream.Count)
{
List <bool> chunk = bitStream.GetRange(i, currentCodeWidth);
chunk.Reverse();
int code = GlobalUtilities.ConvertBitsToInt(chunk);
codeStream.Add(code);
}
i += currentCodeWidth;
}
return(codeStream);
}
public List <byte> Pack(List <int> codeStream)
{
List <byte> packedBytes = new List <byte>();
List <bool> bits = new List <bool>();
int currentCodeWidth = LzwMinimumCodeSize + 1;
int codeCount = 0;
int codeWidthIncreaseThreshold = (int)Math.Pow(2, currentCodeWidth) - 1;
foreach (int code in codeStream)
{
if (codeCount >= codeWidthIncreaseThreshold)
{
currentCodeWidth++;
codeWidthIncreaseThreshold = (int)Math.Pow(2, currentCodeWidth) - 1;
}
List <bool> codeBits = GlobalUtilities.ConvertIntToBits(code, currentCodeWidth);
bits.AddRange(codeBits);
codeCount++;
}
int zeroesNeeded = 8 - (bits.Count % 8);
for (int i = 0; i < zeroesNeeded; i++)
{
bits.Add(false);
}
for (int i = 0; i < bits.Count; i += 8)
{
List <bool> reversedByte = bits.GetRange(i, 8);
reversedByte.Reverse();
packedBytes.Add(GlobalUtilities.ConvertBitsToByte(reversedByte.ToArray()));
}
return(packedBytes);
}
