private static int Codes(BitStream bitStream, Huffman lencode, Huffman distcode, bool lastBlock)
{
int symbol;
do
{
symbol = Decode(bitStream, lencode);
if (symbol < 0)
{
throw new ArgumentOutOfRangeException("invalid symbol.");
}
if (symbol < 256)
{
bitStream.OutBuffer.Add((byte)symbol);
//bitStream.OutBufferWithHeader.Add((byte)symbol);
//if (bitStream.OutBuffer.Count() % 65535 == 0)
//{
// Console.WriteLine("blocked");
// var blocks = bitStream.OutBuffer.Count() / 65535;
// bitStream.OutBufferWithHeader.InsertRange((65535 + 5) * (blocks - 1), BlockHeader(65535, false));
//}
}
else if (symbol > 256)
{
symbol -= 257;
if (symbol >= 29)
{
throw new Exception("Invalid fixed code.");
}
var len = lens[symbol] + bitStream.GetNextBitsReverse(lext[symbol]);
symbol = Decode(bitStream, distcode);
if (symbol < 0)
{
throw new ArgumentOutOfRangeException("invalid symbol.");
}
var dist = dists[symbol] + bitStream.GetNextBitsReverse(dext[symbol]);
// copy length bytes from distance bytes back.
for (int i = 0; i < len; i++)
{
bitStream.OutBuffer.Add(bitStream.OutBuffer[bitStream.OutBuffer.Count() - dist]);
//bitStream.OutBufferWithHeader.Add(bitStream.OutBuffer[bitStream.OutBuffer.Count() - dist]);
//if (bitStream.OutBuffer.Count() % 65535 == 0)
//{
// Console.WriteLine("blocked");
// var blocks = bitStream.OutBuffer.Count() / 65535;
// bitStream.OutBufferWithHeader.InsertRange((65535 + 5) * (blocks - 1), BlockHeader(65535, false));
//}
}
}
} while (symbol != 256);
//if (lastBlock)
//{
// var blocks = bitStream.OutBuffer.Count() / 65535;
// bitStream.OutBufferWithHeader.InsertRange((65535 + 5) * (blocks - 1), BlockHeader((ushort)(bitStream.OutBuffer.Count() % 65535), true));
//}
return(0);
}
static void Decode(ref PNG png)
{
Console.WriteLine($"\nDecoding zlib blocks...");
Stopwatch stopWatch = new Stopwatch();
stopWatch.Start();
uint idatLength = 0;
foreach (var chunk in png.IDATList)
{
idatLength += chunk.ChunkLength;
}
byte[] idatData = new byte[idatLength];
var offset = 0;
for (int i = 0; i < png.IDATList.Count(); i++)
{
Array.Copy(png.IDATList[i].ChunkData, 0, idatData, offset, (int)png.IDATList[i].ChunkLength);
offset += (int)png.IDATList[i].ChunkLength;
}
Stream idatStream = new MemoryStream(idatData);
var zlibHeader = new byte[2];
idatStream.Read(zlibHeader, 0, 2);
var bitBuffer = new byte[idatLength - 6]; // subtract 2 byte zlib header and 4 byte adler checksum.
idatStream.Read(bitBuffer, 0, (int)(idatLength - 6));
idatStream.Dispose();
BitArray bitArray = new BitArray(bitBuffer);
BitStream bs = new BitStream(bitArray);
bool lastBlock;
byte compression;
do
{
lastBlock = bs.GetNextBitsReverse(1) == 1;
compression = (byte)bs.GetNextBitsReverse(2);
if (compression == 0)
{
Console.WriteLine($"Zlib block already uncompressed...");
bs.GetNextBitsReverse(5);
ushort len = bs.GetNextShortReverse();
ushort nen = (ushort)~bs.GetNextShortReverse();
if (nen != len)
{
throw new Exception("Nen does not complement Len.");
}
for (int i = 0; i < len; i++)
{
bs.GetNextBitsReverse(8);
}
}
else if (compression == 1)
{
Console.WriteLine($"Uncompressing {(lastBlock ? "last " : "")}zlib block...");
Puff.ParseFixed(bs, lastBlock);
}
else if (compression == 2)
{
Console.WriteLine($"Uncompressing {(lastBlock ? "last " : "")}zlib block...");
Puff.ParseDynamic(bs, lastBlock);
}
}while (lastBlock == false);
if (compression != 0)
{
var adler = new Adler32();
adler.Update(bs.OutBuffer.ToArray());
byte[] adlerbytearray = BitConverter.GetBytes((int)adler.Value);
Array.Reverse(adlerbytearray, 0, adlerbytearray.Length);
Console.WriteLine($"Adler32 checksum = {adlerbytearray[0]} {adlerbytearray[1]} {adlerbytearray[2]} {adlerbytearray[3]}");
var numblocks = (bs.OutBuffer.Count()) / 65500;
var numblocksRem = (bs.OutBuffer.Count()) % 65500;
var splitBlocklist = new List <byte>();
if (numblocks > 0)
{
for (int j = 0; j < numblocks; j++)
{
InsertBlockHeader(splitBlocklist, 65500, false);
for (int i = 0; i < 65500; i++)
{
splitBlocklist.Add(bs.OutBuffer[i + j * 65500]);
}
}
InsertBlockHeader(splitBlocklist, (ushort)numblocksRem, true);
for (int i = (int)(bs.OutBuffer.Count() - numblocksRem); i < (bs.OutBuffer.Count()); i++)
{
splitBlocklist.Add(bs.OutBuffer[i]);
}
}
else
{
InsertBlockHeader(splitBlocklist, (ushort)numblocksRem, true);
for (int i = (int)(bs.OutBuffer.Count() - numblocksRem); i < (bs.OutBuffer.Count()); i++)
{
splitBlocklist.Add(bs.OutBuffer[i]);
}
}
for (int i = 0; i < adlerbytearray.Length; i++)
{
splitBlocklist.Add(adlerbytearray[i]);
}
byte[] newChunkData = new byte[splitBlocklist.Count() + 2];
zlibHeader.CopyTo(newChunkData, 0);
splitBlocklist.ToArray().CopyTo(newChunkData, 2);
var ncdChunks = newChunkData.Length / 65500;
var ncdRem = newChunkData.Length % 65500;
png.IDATList.Clear();
for (int i = 0; i < ncdChunks; i++)
{
IDATChunk newIdatChunk = new IDATChunk();
newIdatChunk.ChunkData = newChunkData.SubArray(i * 65500, 65500);
png.IDATList.Add(newIdatChunk);
}
IDATChunk finalIdatChunk = new IDATChunk();
finalIdatChunk.ChunkData = newChunkData.SubArray(newChunkData.Length - ncdRem, ncdRem);
png.IDATList.Add(finalIdatChunk);
}
stopWatch.Stop();
string elapsedTime = stopWatch.Elapsed.FormatTime();
Console.WriteLine($"Total decode time = {elapsedTime}");
}
public static int ParseDynamic(BitStream bitStream, bool lastBlock)
{
short[] lengths = new short[MAXCODES];
int nlen = bitStream.GetNextBitsReverse(5) + 257;
int ndist = bitStream.GetNextBitsReverse(5) + 1;
int ncode = bitStream.GetNextBitsReverse(4) + 4;
if (nlen > MAXLCODES || ndist > MAXDCODES)
{
throw new Exception("bad counts");
}
for (int i = 0; i < ncode; i++)
{
lengths[order[i]] = (short)bitStream.GetNextBitsReverse(3);
}
for (int i = ncode; i < 19; i++)
{
lengths[order[i]] = 0;
}
//for (int i = 0; i < lengths.Length; i++)
//{
// Console.WriteLine($"symbol {i} has a code length of {lengths[i]}");
//}
var lencode = new Huffman(new short[MAXBITS + 1], new short[MAXLCODES]);
var distcode = new Huffman(new short[MAXBITS + 1], new short[MAXDCODES]);
var err = Construct(ref lencode, lengths, 19);
if (err != 0)
{
throw new Exception("complete code set required here; code lengths codes incomplete.");
}
//for (int i = 0; i < lencode.count.Length; i++)
//{
// Console.WriteLine($"{lencode.count[i]} symbols of length {i}");
//}
var index = 0;
while (index < nlen + ndist)
{
var symbol = Decode(bitStream, lencode);
var len = 0;
if (symbol < 0)
{
throw new ArgumentOutOfRangeException("invalid symbol");
}
if (symbol < 16)
{
lengths[index++] = (short)symbol;
}
else
{
if (symbol == 16)
{
if (index == 0)
{
throw new ArgumentOutOfRangeException("no preceeding length to reference!");
}
len = lengths[index - 1];
symbol = 3 + bitStream.GetNextBitsReverse(2);
}
else if (symbol == 17)
{
symbol = 3 + bitStream.GetNextBitsReverse(3);
}
else
{
symbol = 11 + bitStream.GetNextBitsReverse(7);
}
if (index + symbol > nlen + ndist)
{
throw new ArgumentOutOfRangeException("too many lengths!");
}
while (symbol-- > 0)
{
lengths[index++] = (short)len;
}
}
}
if (lengths[256] == 0)
{
throw new Exception("no end of block code");
}
err = Construct(ref lencode, lengths, nlen);
if (err != 0 & (err < 0 || nlen != lencode.count[0] + lencode.count[1]))
{
throw new ArgumentException("incomplete code ok only for single length 1 code.");
}
var _lengths = new short[MAXDCODES];
Array.Copy(lengths, nlen, _lengths, 0, MAXDCODES);
err = Construct(ref distcode, _lengths, ndist);
if (err != 0 & (err < 0 || nlen != distcode.count[0] + distcode.count[1]))
{
throw new ArgumentException("incomplete code ok only for single length 1 code.");
}
return(Codes(bitStream, lencode, distcode, lastBlock));
}