public DecodeTable BD; // Decode bit lengths in Huffman table.
public void Init()
{
this.LD = new DecodeTable();
this.DD = new DecodeTable();
this.LDD = new DecodeTable();
this.RD = new DecodeTable();
this.BD = new DecodeTable();
}
public DecodeTable BD; // Decode bit lengths in Huffman table.
public void Init()
{
LD = new DecodeTable();
DD = new DecodeTable();
LDD = new DecodeTable();
RD = new DecodeTable();
BD = new DecodeTable();
}
private uint DecodeNumber(BitInput Inp, DecodeTable Dec)
{
// Left aligned 15 bit length raw bit field.
uint BitField = Inp.getbits() & 0xfffe;
if (BitField < Dec.DecodeLen[Dec.QuickBits])
{
uint Code = BitField >> (int)(16 - Dec.QuickBits);
Inp.addbits(Dec.QuickLen[Code]);
return(Dec.QuickNum[Code]);
}
// Detect the real bit length for current code.
uint Bits = 15;
for (uint I = Dec.QuickBits + 1; I < 15; I++)
{
if (BitField < Dec.DecodeLen[I])
{
Bits = I;
break;
}
}
Inp.addbits(Bits);
// Calculate the distance from the start code for current bit length.
uint Dist = BitField - Dec.DecodeLen[Bits - 1];
// Start codes are left aligned, but we need the normal right aligned
// number. So we shift the distance to the right.
Dist >>= (int)(16 - Bits);
// Now we can calculate the position in the code list. It is the sum
// of first position for current bit length and right aligned distance
// between our bit field and start code for current bit length.
uint Pos = Dec.DecodePos[Bits] + Dist;
// Out of bounds safety check required for damaged archives.
if (Pos >= Dec.MaxNum)
{
Pos = 0;
}
// Convert the position in the code list to position in alphabet
// and return it.
return(Dec.DecodeNum[Pos]);
}
void UnpInitData20(bool Solid)
{
if (!Solid)
{
TablesRead2 = false;
UnpAudioBlock = false;
UnpChannelDelta = 0;
UnpCurChannel = 0;
UnpChannels = 1;
//memset(AudV,0,sizeof(AudV));
AudV = new AudioVariables[4];
Utility.Memset(UnpOldTable20, 0, UnpOldTable20.Length);
//memset(MD,0,sizeof(MD));
MD = new DecodeTable[4];
}
}
private void UnpInitData20(bool Solid)
{
if (!Solid)
{
TablesRead2 = false;
UnpAudioBlock = false;
UnpChannelDelta = 0;
UnpCurChannel = 0;
UnpChannels = 1;
//memset(AudV,0,sizeof(AudV));
AudV = new AudioVariables[4];
new Span <byte>(UnpOldTable20).Clear();
//memset(MD,0,sizeof(MD));
MD = new DecodeTable[4];
}
}
// LengthTable contains the length in bits for every element of alphabet.
// Dec is the structure to decode Huffman code/
// Size is size of length table and DecodeNum field in Dec structure,
private void MakeDecodeTables(byte[] LengthTable, int offset, DecodeTable Dec, uint Size)
{
// Size of alphabet and DecodePos array.
Dec.MaxNum = Size;
// Calculate how many entries for every bit length in LengthTable we have.
uint[] LengthCount = new uint[16];
//memset(LengthCount,0,sizeof(LengthCount));
for (size_t I = 0; I < Size; I++)
{
LengthCount[LengthTable[offset + I] & 0xf]++;
}
// We must not calculate the number of zero length codes.
LengthCount[0] = 0;
// Set the entire DecodeNum to zero.
//memset(Dec->DecodeNum,0,Size*sizeof(*Dec->DecodeNum));
Utility.FillFast <ushort>(Dec.DecodeNum, 0);
// Initialize not really used entry for zero length code.
Dec.DecodePos[0] = 0;
// Start code for bit length 1 is 0.
Dec.DecodeLen[0] = 0;
// Right aligned upper limit code for current bit length.
uint UpperLimit = 0;
for (int I = 1; I < 16; I++)
{
// Adjust the upper limit code.
UpperLimit += LengthCount[I];
// Left aligned upper limit code.
uint LeftAligned = UpperLimit << (16 - I);
// Prepare the upper limit code for next bit length.
UpperLimit *= 2;
// Store the left aligned upper limit code.
Dec.DecodeLen[I] = (uint)LeftAligned;
// Every item of this array contains the sum of all preceding items.
// So it contains the start position in code list for every bit length.
Dec.DecodePos[I] = Dec.DecodePos[I - 1] + LengthCount[I - 1];
}
// Prepare the copy of DecodePos. We'll modify this copy below,
// so we cannot use the original DecodePos.
uint[] CopyDecodePos = new uint[Dec.DecodePos.Length];
//memcpy(CopyDecodePos,Dec->DecodePos,sizeof(CopyDecodePos));
Array.Copy(Dec.DecodePos, 0, CopyDecodePos, 0, CopyDecodePos.Length);
// For every bit length in the bit length table and so for every item
// of alphabet.
for (uint I = 0; I < Size; I++)
{
// Get the current bit length.
byte _CurBitLength = (byte)(LengthTable[offset + I] & 0xf);
if (_CurBitLength != 0)
{
// Last position in code list for current bit length.
uint LastPos = CopyDecodePos[_CurBitLength];
// Prepare the decode table, so this position in code list will be
// decoded to current alphabet item number.
Dec.DecodeNum[LastPos] = (ushort)I;
// We'll use next position number for this bit length next time.
// So we pass through the entire range of positions available
// for every bit length.
CopyDecodePos[_CurBitLength]++;
}
}
// Define the number of bits to process in quick mode. We use more bits
// for larger alphabets. More bits means that more codes will be processed
// in quick mode, but also that more time will be spent to preparation
// of tables for quick decode.
switch (Size)
{
case NC:
case NC20:
case NC30:
Dec.QuickBits = MAX_QUICK_DECODE_BITS;
break;
default:
Dec.QuickBits = MAX_QUICK_DECODE_BITS - 3;
break;
}
// Size of tables for quick mode.
uint QuickDataSize = 1U << (int)Dec.QuickBits;
// Bit length for current code, start from 1 bit codes. It is important
// to use 1 bit instead of 0 for minimum code length, so we are moving
// forward even when processing a corrupt archive.
//uint CurBitLength=1;
byte CurBitLength = 1;
// For every right aligned bit string which supports the quick decoding.
for (uint Code = 0; Code < QuickDataSize; Code++)
{
// Left align the current code, so it will be in usual bit field format.
uint BitField = Code << (int)(16 - Dec.QuickBits);
// Prepare the table for quick decoding of bit lengths.
// Find the upper limit for current bit field and adjust the bit length
// accordingly if necessary.
while (CurBitLength < Dec.DecodeLen.Length && BitField >= Dec.DecodeLen[CurBitLength])
{
CurBitLength++;
}
// Translation of right aligned bit string to bit length.
Dec.QuickLen[Code] = CurBitLength;
// Prepare the table for quick translation of position in code list
// to position in alphabet.
// Calculate the distance from the start code for current bit length.
uint Dist = BitField - Dec.DecodeLen[CurBitLength - 1];
// Right align the distance.
Dist >>= (16 - CurBitLength);
// Now we can calculate the position in the code list. It is the sum
// of first position for current bit length and right aligned distance
// between our bit field and start code for current bit length.
uint Pos;
if (CurBitLength < Dec.DecodePos.Length &&
(Pos = Dec.DecodePos[CurBitLength] + Dist) < Size)
{
// Define the code to alphabet number translation.
Dec.QuickNum[Code] = Dec.DecodeNum[Pos];
}
else
{
// Can be here for length table filled with zeroes only (empty).
Dec.QuickNum[Code] = 0;
}
}
}
