// 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()
{
var bitLengthCount = new uint[17];
foreach (int codeLength in codeLengthArray)
{
bitLengthCount[codeLength]++;
}
bitLengthCount[0] = 0; // clear count for length 0
var nextCode = new uint[17];
uint tempCode = 0;
for (var bits = 1; bits <= 16; bits++)
{
tempCode = (tempCode + bitLengthCount[bits - 1]) << 1;
nextCode[bits] = tempCode;
}
var code = new uint[MaxLiteralTreeElements];
for (var i = 0; i < codeLengthArray.Length; i++)
{
int len = codeLengthArray[i];
if (len > 0)
{
code[i] = FastEncoderStatics.BitReverse(nextCode[len], len);
nextCode[len]++;
}
}
return(code);
}
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
var codeInfo =
FastEncoderStatics.FastEncoderLiteralCodeInfo[
FastEncoderStatics.NumChars + 1 - FastEncoderWindow.MinMatch + matchLen];
var 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);
var extraBits = (int)(codeInfo >> 4) & 15;
if (extraBits != 0)
{
output.WriteBits(extraBits, (uint)matchPos & FastEncoderStatics.BitMask[extraBits]);
}
}
private UInt32[] CalculateHuffmanCode()
{
UInt32[] array = new UInt32[17];
Byte[] array2 = this.codeLengthArray;
for (Int32 i = 0; i < (Int32)array2.Length; i++)
{
Int32 num = (Int32)array2[i];
array[num] += 1u;
}
array[0] = 0u;
UInt32[] array3 = new UInt32[17];
UInt32 num2 = 0u;
for (Int32 j = 1; j <= 16; j++)
{
num2 = num2 + array[j - 1] << 1;
array3[j] = num2;
}
UInt32[] array4 = new UInt32[288];
for (Int32 k = 0; k < (Int32)this.codeLengthArray.Length; k++)
{
Int32 num3 = (Int32)this.codeLengthArray[k];
if (num3 > 0)
{
array4[k] = FastEncoderStatics.BitReverse(array3[num3], num3);
array3[num3] += 1u;
}
}
return(array4);
}
private uint[] CalculateHuffmanCode()
{
uint[] array = new uint[17];
byte[] array2 = this.codeLengthArray;
for (int i = 0; i < array2.Length; i++)
{
int num = (int)array2[i];
array[num] += 1u;
}
array[0] = 0u;
uint[] array3 = new uint[17];
uint num2 = 0u;
for (int j = 1; j <= 16; j++)
{
num2 = num2 + array[j - 1] << 1;
array3[j] = num2;
}
uint[] array4 = new uint[288];
for (int k = 0; k < this.codeLengthArray.Length; k++)
{
int num3 = (int)this.codeLengthArray[k];
if (num3 > 0)
{
array4[k] = FastEncoderStatics.BitReverse(array3[num3], num3);
array3[num3] += 1u;
}
}
return(array4);
}
internal static void WriteMatch(int matchLen, int matchPos, OutputBuffer output)
{
uint num = FastEncoderStatics.FastEncoderLiteralCodeInfo[254 + matchLen];
int num2 = (int)(num & 31u);
if (num2 <= 16)
{
output.WriteBits(num2, num >> 5);
}
else
{
output.WriteBits(16, num >> 5 & 65535u);
output.WriteBits(num2 - 16, num >> 21);
}
num = FastEncoderStatics.FastEncoderDistanceCodeInfo[FastEncoderStatics.GetSlot(matchPos)];
output.WriteBits((int)(num & 15u), num >> 8);
int num3 = (int)(num >> 4 & 15u);
if (num3 != 0)
{
output.WriteBits(num3, (uint)(matchPos & (int)FastEncoderStatics.BitMask[num3]));
}
}
