// Calculate the huffman code for each character based on the code length for each character.
// This algorithm is described in standard RFC 1951
private uint[] CalculateHuffmanCode()
{
uint[] bitLengthCount = new uint[17];
foreach (int codeLength in _codeLengthArray)
{
bitLengthCount[codeLength]++;
}
bitLengthCount[0] = 0; // clear count for length 0
uint[] nextCode = new uint[17];
uint tempCode = 0;
for (int bits = 1; bits <= 16; bits++)
{
tempCode = (tempCode + bitLengthCount[bits - 1]) << 1;
nextCode[bits] = tempCode;
}
uint[] code = new uint[MaxLiteralTreeElements];
for (int i = 0; i < _codeLengthArray.Length; i++)
{
int len = _codeLengthArray[i];
if (len > 0)
{
code[i] = FastEncoderStatics.BitReverse(nextCode[len], len);
nextCode[len]++;
}
}
return(code);
}
static internal void WriteMatch(int matchLen, int matchPos, OutputBuffer output)
{
Debug.Assert(matchLen >= FastEncoderWindow.MinMatch && matchLen <= FastEncoderWindow.MaxMatch, "Illegal currentMatch length!");
Debug.WriteLineIf(CompressionTracingSwitch.Verbose, String.Format(CultureInfo.InvariantCulture, "Match: {0}:{1}", matchLen, matchPos), "Compression");
// Get the code information for a match code
uint codeInfo = FastEncoderStatics.FastEncoderLiteralCodeInfo[(FastEncoderStatics.NumChars + 1 - FastEncoderWindow.MinMatch) + matchLen];
int codeLen = (int)codeInfo & 31;
Debug.Assert(codeLen != 0, "Invalid Match Length!");
if (codeLen <= 16)
{
output.WriteBits(codeLen, codeInfo >> 5);
}
else
{
output.WriteBits(16, (codeInfo >> 5) & 65535);
output.WriteBits(codeLen - 16, codeInfo >> (5 + 16));
}
// Get the code information for a distance code
codeInfo = FastEncoderStatics.FastEncoderDistanceCodeInfo[FastEncoderStatics.GetSlot(matchPos)];
output.WriteBits((int)(codeInfo & 15), codeInfo >> 8);
int extraBits = (int)(codeInfo >> 4) & 15;
if (extraBits != 0)
{
output.WriteBits(extraBits, (uint)matchPos & FastEncoderStatics.BitMask[extraBits]);
}
}
internal static void WriteMatch(int matchLen, int matchPos, OutputBuffer output)
{
Debug.Assert(matchLen >= FastEncoderWindow.MinMatch && matchLen <= FastEncoderWindow.MaxMatch, "Illegal currentMatch length!");
// Get the code information for a match code
uint codeInfo = FastEncoderStatics.FastEncoderLiteralCodeInfo[(FastEncoderStatics.NumChars + 1 - FastEncoderWindow.MinMatch) + matchLen];
int codeLen = (int)codeInfo & 31;
Debug.Assert(codeLen != 0, "Invalid Match Length!");
if (codeLen <= 16)
{
output.WriteBits(codeLen, codeInfo >> 5);
}
else
{
output.WriteBits(16, (codeInfo >> 5) & 65535);
output.WriteBits(codeLen - 16, codeInfo >> (5 + 16));
}
// Get the code information for a distance code
codeInfo = FastEncoderStatics.FastEncoderDistanceCodeInfo[FastEncoderStatics.GetSlot(matchPos)];
output.WriteBits((int)(codeInfo & 15), codeInfo >> 8);
int extraBits = (int)(codeInfo >> 4) & 15;
if (extraBits != 0)
{
output.WriteBits(extraBits, (uint)matchPos & FastEncoderStatics.BitMask[extraBits]);
}
}
private uint[] CalculateHuffmanCode()
{
uint[] numArray = new uint[0x11];
byte[] codeLengthArray = this.codeLengthArray;
for (int i = 0; i < codeLengthArray.Length; i++)
{
int index = codeLengthArray[i];
numArray[index]++;
}
numArray[0] = 0;
uint[] numArray2 = new uint[0x11];
uint num2 = 0;
for (int j = 1; j <= 0x10; j++)
{
numArray2[j] = (num2 + numArray[j - 1]) << 1;
}
uint[] numArray3 = new uint[0x120];
for (int k = 0; k < this.codeLengthArray.Length; k++)
{
int length = this.codeLengthArray[k];
if (length > 0)
{
numArray3[k] = FastEncoderStatics.BitReverse(numArray2[length], length);
numArray2[length]++;
}
}
return(numArray3);
}
internal static void WriteMatch(int matchLen, int matchPos, OutputBuffer output)
{
uint num = FastEncoderStatics.FastEncoderLiteralCodeInfo[0xfe + matchLen];
int n = ((int)num) & 0x1f;
if (n <= 0x10)
{
output.WriteBits(n, num >> 5);
}
else
{
output.WriteBits(0x10, (num >> 5) & 0xffff);
output.WriteBits(n - 0x10, num >> 0x15);
}
num = FastEncoderStatics.FastEncoderDistanceCodeInfo[FastEncoderStatics.GetSlot(matchPos)];
output.WriteBits(((int)num) & 15, num >> 8);
int num3 = ((int)(num >> 4)) & 15;
if (num3 != 0)
{
output.WriteBits(num3, ((uint)matchPos) & FastEncoderStatics.BitMask[num3]);
}
}
