public Picture decodeField(MemoryStream data, int[][] data2, int field, int step)
{
Picture result = null;
FrameHeader header = null;
VLC[] huffTables = new VLC[] { JpegConst.YDC_DEFAULT, JpegConst.CDC_DEFAULT, JpegConst.YAC_DEFAULT,
JpegConst.CAC_DEFAULT };
int[][] quant = new int[4][];
ScanHeader scan = null;
while (data.hasRemaining())
{
int marker = data.get() & 0xff;
if (marker == 0)
{
continue;
}
if (marker != 0xFF)
{
throw new Exception("@" + data.Position + " Marker expected: 0x"
+ marker.ToString("X"));
}
int b;
while ((b = data.get() & 0xff) == 0xff)
{
;
}
// Debug.trace("%s", JpegConst.toString(b));
if (b == JpegConst.SOF0)
{
header = FrameHeader.read(data);
// Debug.trace(" %s", image.frame);
}
else if (b == JpegConst.DHT)
{
int len1 = data.getShort() & 0xffff;
MemoryStream buf = StreamExtensions.read(data, len1 - 2);
while (buf.hasRemaining())
{
int tableNo = buf.get() & 0xff;
huffTables[(tableNo & 1) | ((tableNo >> 3) & 2)] = readHuffmanTable(buf);
}
}
else if (b == JpegConst.DQT)
{
int len4 = data.getShort() & 0xffff;
MemoryStream buf = StreamExtensions.read(data, len4 - 2);
while (buf.hasRemaining())
{
int ind = buf.get() & 0xff;
quant[ind] = readQuantTable(buf);
}
}
else if (b == JpegConst.SOS)
{
if (scan != null)
{
throw new Exception("unhandled - more than one scan header");
}
scan = ScanHeader.read(data);
// Debug.trace(" %s", image.scan);
result = decodeScan(readToMarker(data), header, scan, huffTables, quant, data2, field, step);
}
else if (b == JpegConst.SOI || (b >= JpegConst.RST0 && b <= JpegConst.RST7))
{
// Nothing
}
else if (b == JpegConst.EOI)
{
break;
}
else if (b >= JpegConst.APP0 && b <= JpegConst.COM)
{
int len3 = data.getShort() & 0xffff;
StreamExtensions.read(data, len3 - 2);
}
else if (b == JpegConst.DRI)
{
int lr = data.getShort() & 0xffff;
int ri = data.getShort() & 0xffff;
// Debug.trace("DRI Lr: %d Ri: %d", lr, ri);
//Asserts.assertEquals(0, ri);
}
else
{
throw new Exception("unhandled marker " + JpegConst.toString(b));
}
}
return(result);
}