internal static void EncodeBinary(IDataCoder coder, byte[] ctx, int bits, int x, int offset = 0)
{
// Require 2^bits-1 contexts
int n = 1;
int m = (1 << bits);
while (n < m)
{
x = (x & (m - 1)) << 1;
int b = (x >> bits);
coder.Encoder(b, ref ctx[n - 1 + offset]);
n = (n << 1) | b;
}
}
internal static void EncodeRaw(IDataCoder coder, int bits, int x)
{
int n = 1;
int count = 0;
int m = (1 << bits);
while (n < m)
{
x = (x & (m - 1)) << 1;
int b = (x >> bits);
coder.Encoder(b);
n = (n << 1) | b;
count++;
}
}
/// <summary>
/// Encodes a sequence of buckets in a given block.
/// </summary>
/// <param name="zp"></param>
/// <param name="bit"></param>
/// <param name="band"></param>
/// <param name="blk"></param>
/// <param name="eblk"></param>
/// <param name="fbucket"></param>
/// <param name="nbucket"></param>
public void EncodeBuckets(IDataCoder zp, int bit, int band,
InterWaveBlock blk, InterWaveBlock eblk, int fbucket, int nbucket)
{
// compute state of all coefficients in all buckets
int bbstate = EncodePrepare(band, fbucket, nbucket, blk, eblk);
// code root bit
if ((nbucket < 16) || (bbstate & Active) != 0)
{
bbstate |= New;
}
else if ((bbstate & Unk) != 0)
{
zp.Encoder((bbstate & New) != 0 ? 1 : 0, ref _CtxRoot);
}
// code bucket bits
if ((bbstate & New) != 0)
{
for (int buckno = 0; buckno < nbucket; buckno++)
{
// Code bucket bit
if ((_BucketState[buckno] & Unk) != 0)
{
// Context
int ctx = 0;
if (band > 0)
{
int k = (fbucket + buckno) << 2;
short[] b = eblk.GetBlock(k >> 4);
if (b != null)
{
k = k & 0xf;
if (b[k] != 0)
{
ctx += 1;
}
if (b[k + 1] != 0)
{
ctx += 1;
}
if (b[k + 2] != 0)
{
ctx += 1;
}
if (ctx < 3 && b[k + 3] != 0)
{
ctx += 1;
}
}
}
if ((bbstate & Active) != 0)
{
ctx |= 4;
}
// Code
zp.Encoder((_BucketState[buckno] & New) != 0 ? 1 : 0, ref _CtxBucket[band][ctx]);
}
}
}
// code new active coefficient (with their sign)
if ((bbstate & New) != 0)
{
int thres = _QuantHigh[band];
sbyte[] cstate = _CoefficientState;
for (int buckno = 0, cidx = 0; buckno < nbucket; buckno++, cidx += 16)
{
if ((_BucketState[buckno] & New) != 0)
{
int i;
int gotcha = 0;
const int maxgotcha = 7;
for (i = 0; i < 16; i++)
{
if ((cstate[i + cidx] & Unk) != 0)
{
gotcha += 1;
}
}
short[] pcoeff = blk.GetBlock(fbucket + buckno);
short[] epcoeff = eblk.GetInitializedBlock(fbucket + buckno);
// iterate within bucket
for (i = 0; i < 16; i++)
{
if ((cstate[i] & Unk) != 0)
{
// Prepare context
int ctx = 0;
if (gotcha >= maxgotcha)
{
ctx = maxgotcha;
}
else
{
ctx = gotcha;
}
if ((_BucketState[buckno] & Active) != 0)
{
ctx |= 8;
}
// Code
zp.Encoder((cstate[i] & New) != 0 ? 1 : 0, ref _CtxStart[ctx]);
if ((cstate[i] & New) != 0)
{
// Code sign
zp.IWEncoder((pcoeff[i] < 0) ? true : false);
// Set encoder state
if (band == 0)
{
thres = _QuantLow[i];
}
epcoeff[i] = (short)(thres + (thres >> 1));
}
if ((cstate[i] & New) != 0)
{
gotcha = 0;
}
else if (gotcha > 0)
{
gotcha -= 1;
}
}
}
}
}
}
// code mantissa bits
if ((bbstate & Active) != 0)
{
int thres = _QuantHigh[band];
sbyte[] cstate = _CoefficientState;
for (int buckno = 0, cidx = 0; buckno < nbucket; buckno++, cidx += 16)
{
if ((_BucketState[buckno] & Active) != 0)
{
short[] pcoeff = blk.GetBlock(fbucket + buckno);
short[] epcoeff = eblk.GetInitializedBlock(fbucket + buckno);
for (int i = 0; i < 16; i++)
{
if ((cstate[i] & Active) != 0)
{
// get coefficient
int coeff = pcoeff[i];
int ecoeff = epcoeff[i];
if (coeff < 0)
{
coeff = -coeff;
}
// get band zero thresholds
if (band == 0)
{
thres = _QuantLow[i];
}
// compute mantissa bit
int pix = 0;
if (coeff >= ecoeff)
{
pix = 1;
}
// encode second or lesser mantissa bit
if (ecoeff <= 3 * thres)
{
zp.Encoder(pix, ref _CtxMant);
}
else
{
zp.IWEncoder(!!(pix != 0));
}
// adjust epcoeff
epcoeff[i] = (short)(ecoeff - (pix != 0 ? 0 : thres) + (thres >> 1));
}
}
}
}
}
}