private bool ReadTables20()
{
byte[] BitLength = new byte[PackDef.BC20];
byte[] Table = new byte[PackDef.MC20 * 4];
int TableSize, N, I;
if (inAddr > readTop - 25)
{
if (!unpReadBuf())
{
return(false);
}
}
int BitField = GetBits();
UnpAudioBlock = (BitField & 0x8000);
if (0 == (BitField & 0x4000))
{
// memset(UnpOldTable20,0,sizeof(UnpOldTable20));
new Span <byte>(UnpOldTable20).Fill(0);
}
AddBits(2);
if (UnpAudioBlock != 0)
{
UnpChannels = ((Utility.URShift(BitField, 12)) & 3) + 1;
if (UnpCurChannel >= UnpChannels)
{
UnpCurChannel = 0;
}
AddBits(2);
TableSize = PackDef.MC20 * UnpChannels;
}
else
{
TableSize = PackDef.NC20 + PackDef.DC20 + PackDef.RC20;
}
for (I = 0; I < PackDef.BC20; I++)
{
BitLength[I] = (byte)(Utility.URShift(GetBits(), 12));
AddBits(4);
}
UnpackUtility.makeDecodeTables(BitLength, 0, BD, PackDef.BC20);
I = 0;
while (I < TableSize)
{
if (inAddr > readTop - 5)
{
if (!unpReadBuf())
{
return(false);
}
}
int Number = this.decodeNumber(BD);
if (Number < 16)
{
Table[I] = (byte)((Number + UnpOldTable20[I]) & 0xf);
I++;
}
else if (Number == 16)
{
N = (Utility.URShift(GetBits(), 14)) + 3;
AddBits(2);
while (N-- > 0 && I < TableSize)
{
Table[I] = Table[I - 1];
I++;
}
}
else
{
if (Number == 17)
{
N = (Utility.URShift(GetBits(), 13)) + 3;
AddBits(3);
}
else
{
N = (Utility.URShift(GetBits(), 9)) + 11;
AddBits(7);
}
while (N-- > 0 && I < TableSize)
{
Table[I++] = 0;
}
}
}
if (inAddr > readTop)
{
return(true);
}
if (UnpAudioBlock != 0)
{
for (I = 0; I < UnpChannels; I++)
{
UnpackUtility.makeDecodeTables(Table, I * PackDef.MC20, MD[I], PackDef.MC20);
}
}
else
{
UnpackUtility.makeDecodeTables(Table, 0, LD, PackDef.NC20);
UnpackUtility.makeDecodeTables(Table, PackDef.NC20, DD, PackDef.DC20);
UnpackUtility.makeDecodeTables(Table, PackDef.NC20 + PackDef.DC20, RD, PackDef.RC20);
}
// memcpy(UnpOldTable20,Table,sizeof(UnpOldTable20));
for (int i = 0; i < UnpOldTable20.Length; i++)
{
UnpOldTable20[i] = Table[i];
}
return(true);
}
private bool ReadTables()
{
byte[] bitLength = new byte[PackDef.BC];
byte[] table = new byte[PackDef.HUFF_TABLE_SIZE];
if (inAddr > readTop - 25)
{
if (!unpReadBuf())
{
return(false);
}
}
AddBits((8 - inBit) & 7);
long bitField = GetBits() & unchecked ((int)0xffFFffFF);
if ((bitField & 0x8000) != 0)
{
unpBlockType = BlockTypes.BLOCK_PPM;
return(ppm.DecodeInit(this, PpmEscChar));
}
unpBlockType = BlockTypes.BLOCK_LZ;
prevLowDist = 0;
lowDistRepCount = 0;
if ((bitField & 0x4000) == 0)
{
Utility.Fill(unpOldTable, (byte)0); // memset(UnpOldTable,0,sizeof(UnpOldTable));
}
AddBits(2);
for (int i = 0; i < PackDef.BC; i++)
{
int length = (Utility.URShift(GetBits(), 12)) & 0xFF;
AddBits(4);
if (length == 15)
{
int zeroCount = (Utility.URShift(GetBits(), 12)) & 0xFF;
AddBits(4);
if (zeroCount == 0)
{
bitLength[i] = 15;
}
else
{
zeroCount += 2;
while (zeroCount-- > 0 && i < bitLength.Length)
{
bitLength[i++] = 0;
}
i--;
}
}
else
{
bitLength[i] = (byte)length;
}
}
UnpackUtility.makeDecodeTables(bitLength, 0, BD, PackDef.BC);
int TableSize = PackDef.HUFF_TABLE_SIZE;
for (int i = 0; i < TableSize;)
{
if (inAddr > readTop - 5)
{
if (!unpReadBuf())
{
return(false);
}
}
int Number = this.decodeNumber(BD);
if (Number < 16)
{
table[i] = (byte)((Number + unpOldTable[i]) & 0xf);
i++;
}
else if (Number < 18)
{
int N;
if (Number == 16)
{
N = (Utility.URShift(GetBits(), 13)) + 3;
AddBits(3);
}
else
{
N = (Utility.URShift(GetBits(), 9)) + 11;
AddBits(7);
}
while (N-- > 0 && i < TableSize)
{
table[i] = table[i - 1];
i++;
}
}
else
{
int N;
if (Number == 18)
{
N = (Utility.URShift(GetBits(), 13)) + 3;
AddBits(3);
}
else
{
N = (Utility.URShift(GetBits(), 9)) + 11;
AddBits(7);
}
while (N-- > 0 && i < TableSize)
{
table[i++] = 0;
}
}
}
tablesRead = true;
if (inAddr > readTop)
{
return(false);
}
UnpackUtility.makeDecodeTables(table, 0, LD, PackDef.NC);
UnpackUtility.makeDecodeTables(table, PackDef.NC, DD, PackDef.DC);
UnpackUtility.makeDecodeTables(table, PackDef.NC + PackDef.DC, LDD, PackDef.LDC);
UnpackUtility.makeDecodeTables(table, PackDef.NC + PackDef.DC + PackDef.LDC, RD, PackDef.RC);
// memcpy(unpOldTable,table,sizeof(unpOldTable));
Buffer.BlockCopy(table, 0, unpOldTable, 0, unpOldTable.Length);
return(true);
}