public static void WriteBits(
ImageBinWriter s, ref BitBuffer32 bitBuf, PointU16 point)
{
WriteBits(s, ref bitBuf, point.X, point.Y);
}
public static int ProcessDU(
ImageBinWriter s, ref BitBuffer32 bitBuf,
Span <float> CDU, int duStride, Span <float> fdtbl, int DC,
PointU16[] HTDC, PointU16[] HTAC)
{
Debug.Assert(HTDC != null);
Debug.Assert(HTAC != null);
Span <int> DU = stackalloc int[64];
CalculateCDU(CDU, duStride, fdtbl, DU);
int diff = DU[0] - DC;
if (diff == 0)
{
WriteBits(s, ref bitBuf, HTDC[0]);
}
else
{
BitBuffer16 bitBuf16 = CalcBitBuffer16(diff);
WriteBits(s, ref bitBuf, HTDC[bitBuf16.Count]);
WriteBits(s, ref bitBuf, bitBuf16.Value, bitBuf16.Count);
}
int end0pos = 63;
for (; (end0pos > 0) && (DU[end0pos] == 0); end0pos--)
{
}
if (end0pos == 0)
{
WriteBits(s, ref bitBuf, HTAC[0x00]);
return(DU[0]);
}
for (int i = 1; i <= end0pos; i++)
{
int startpos = i;
for (; (DU[i] == 0) && (i <= end0pos); i++)
{
}
int nrzeroes = i - startpos;
if (nrzeroes >= 16)
{
int lng = nrzeroes >> 4;
for (int nrmarker = 1; nrmarker <= lng; nrmarker++)
{
WriteBits(s, ref bitBuf, HTAC[0xF0]);
}
nrzeroes &= 15;
}
BitBuffer16 bitBuf16 = CalcBitBuffer16(DU[i]);
WriteBits(s, ref bitBuf, HTAC[(nrzeroes << 4) + bitBuf16.Count]);
WriteBits(s, ref bitBuf, bitBuf16.Value, bitBuf16.Count);
}
if (end0pos != 63)
{
WriteBits(s, ref bitBuf, HTAC[0x00]);
}
return(DU[0]);
}