private static UInt32 readNBits(ref CAmigaUnpackData amiga, UInt32 n)
{
if (amiga.data == null || amiga.data.Length <= amiga.readPosition)
return 0;
UInt32 returnValue = 0;
try
{
for (Int32 i = 0; i < n; i++)
{
if (amiga.counter <= 0)
{
amiga.counter = 8;
amiga.readPosition--;
amiga.currentByte = amiga.data[amiga.readPosition];
}
returnValue = (UInt32)((returnValue << 1) | (UInt32)(amiga.currentByte & 0x01));
amiga.currentByte >>= 1;
amiga.counter--;
}
}
catch (SystemException)
{
return 0;
}
return returnValue;
}
public static byte[] unpackAmiga2Data(ref byte[] sourceData, Int32 startPosition, Int32 dataLength)
{
if (sourceData == null || (startPosition + dataLength) >= sourceData.Length)
return null;
UInt32 unpackLength = sourceData[startPosition + dataLength - 2];
unpackLength += (UInt32)(sourceData[startPosition + dataLength - 3] << 8);
unpackLength += (UInt32)(sourceData[startPosition + dataLength - 4] << 16);
byte[] returnData = new byte[unpackLength];
UInt32 destinationPosition = (UInt32)(unpackLength);
CAmigaUnpackData amiga = new CAmigaUnpackData(ref sourceData, startPosition + dataLength - 4);
//---zum Entpacken---
UInt32 anzahlWiederholungen = 0;
byte[] offsetSizes = new byte[4];
offsetSizes[0] = sourceData[startPosition + 4];
offsetSizes[1] = sourceData[startPosition + 5];
offsetSizes[2] = sourceData[startPosition + 6];
offsetSizes[3] = sourceData[startPosition + 7];
//-------------------
UInt32 x = 0;
//skip some bits
readNBits(ref amiga, sourceData[startPosition + dataLength - 1]);
while (destinationPosition != 0)
{
if (0 == readNBits(ref amiga, 1))
{
//daten sind nicht gepackt
anzahlWiederholungen = 0;
do
{
x = readNBits(ref amiga, 2);
anzahlWiederholungen += x;
}
while (x == 3); // wenn nicht alle bits ge
for (int i = 0; i <= anzahlWiederholungen; i++)
returnData[--destinationPosition] = (byte)readNBits(ref amiga, 8);
if (destinationPosition == 0)
break;
}
//daten sind gepackt
x = readNBits(ref amiga, 2);
UInt32 n_bits = offsetSizes[x];
UInt32 offset = 0;
anzahlWiederholungen = x + 1;
if (x == 3)
{
if (readNBits(ref amiga, 1) == 0)
offset = readNBits(ref amiga, 7);
else
offset = readNBits(ref amiga, n_bits);
do
{
x = readNBits(ref amiga, 3);
anzahlWiederholungen += x;
}
while (x == 7);
}
else
offset = readNBits(ref amiga, n_bits);
for (int i = 0; i <= anzahlWiederholungen; i++)
{
try
{
returnData[destinationPosition - 1] = returnData[destinationPosition + offset];
destinationPosition--;
}
catch (SystemException)
{
return null;
//throw e;
}
}
if (destinationPosition == 0)
return returnData;
}
return returnData;
}
