private int DecodeSignificantAbsLevel(CAdaptiveHuffman pAHexpt)
{
int iFixed, iLevel;
uint iIndex = (uint)pAHexpt.GetHuff(bitIO);
System.Diagnostics.Debug.Assert( iIndex <= 6 );
pAHexpt.m_iDiscriminant += pAHexpt.m_pDelta[iIndex];
if (iIndex < 2)
{
iLevel = (int)(iIndex + 2);
}
else if (iIndex < 6)
{
iFixed = (int)Constant.aFixedLength[iIndex];
iLevel = (int)Constant.aRemap[iIndex] + bitIO.GetBit16((uint)iFixed);
}
else
{
iFixed = (int)bitIO.GetBit16(4) + 4;
if (iFixed == 19)
{
iFixed += bitIO.GetBit16(2);
if (iFixed == 22)
{
iFixed += bitIO.GetBit16(3);
}
}
iLevel = 2 + (1 << (byte)iFixed);
iIndex = bitIO.GetBit32((uint)iFixed);
iLevel += (int)iIndex;
}
return iLevel;
}
private void DecodeFirstIndex(out int pIndex, out int pSign, CAdaptiveHuffman pAHexpt)
{
pIndex = pAHexpt.GetHuff(bitIO);
pAHexpt.m_iDiscriminant += pAHexpt.m_pDelta[(uint)pIndex];
pAHexpt.m_iDiscriminant1 += pAHexpt.m_pDelta1[(uint)pIndex];
pSign = -bitIO.GetBit16(1);
}
private void DecodeIndex(out int pIndex, out int pSign, int iLoc, CAdaptiveHuffman pAHexpt)
{
if (iLoc < 15)
{
pIndex = pAHexpt.GetHuffShort(bitIO);
pAHexpt.m_iDiscriminant += pAHexpt.m_pDelta[(uint)pIndex];
pAHexpt.m_iDiscriminant1 += pAHexpt.m_pDelta1[(uint)pIndex];
pSign = -bitIO.GetBit16(1);
}
else
if (iLoc == 15)
{
if (!bitIO.GetBool16())
{
pIndex = 0;
}
else
if (!bitIO.GetBool16())
{
pIndex = 2;
}
else
{
pIndex = 1 + 2 * bitIO.GetBit16(1);
}
pSign = -bitIO.GetBit16(1);
}
else { //if (iLoc == 16) { /* deterministic */
int iSL = bitIO.GetBit16(1 + 1);
pIndex = iSL >> 1;
pSign = -(iSL & 1);
}
}
/*************************************************************************
Experimental code -- decodeBlock
SR = <0 1 2> == <last, nonsignificant, significant run>
alphabet 12:
pAHexpt[0] == <SR', SL, SR | first symbol>
alphabet 6:
pAHexpt[1] == <SR', SL | continuous>
pAHexpt[2] == <SR', SL | continuous>
alphabet 4:
pAHexpt[3] == <SR', SL | 2 free slots> (SR may be last or insignificant only)
alphabet f(run) (this can be extended to 6 contexts - SL and SR')
pAHexpt[4] == <run | continuous>
alphabet f(lev) (this can be extended to 9 contexts)
pAHexpt[5-6] == <lev | continuous> first symbol
pAHexpt[7-8] == <lev | continuous> condition on SRn no use
*************************************************************************/
private int DecodeSignificantRun(int iMaxRun, CAdaptiveHuffman pAHexpt)
{
if (iMaxRun < 5)
{
if (iMaxRun == 1 || bitIO.GetBool16())
{
return 1;
}
else
if (iMaxRun == 2 || bitIO.GetBool16())
{
return 2;
}
else
if (iMaxRun == 3 || bitIO.GetBool16())
{
return 3;
}
return 4;
}
int iIndex = pAHexpt.GetHuffShort(bitIO);
//this always uses table 0
iIndex += (int)Constant.gSignificantRunBin[iMaxRun] * 5;
int iRun = Constant.aRemap2[iIndex];
uint iFLC = Constant.gSignificantRunFixedLength[iIndex];
if (iFLC != 0)
{
iRun += bitIO.GetBit16(iFLC);
}
return iRun;
}
