private int refineNonZeroes(Block b, int zig, int zigEnd, int nz, int delta)
{
for (; zig <= zigEnd; zig++)
{
int u = unzig[zig];
if (b[u] == 0)
{
if (nz == 0)
{
break;
}
nz--;
continue;
}
var bit = Bytes.DecodeBit();
if (!bit)
{
continue;
}
if (b[u] >= 0)
{
b[u] += delta;
}
else
{
b[u] -= delta;
}
}
return(zig);
}
private void refine(Block b, Huffman h, int zigStart, int zigEnd, int delta)
{
if (zigStart == 0)
{
if (zigEnd != 0)
{
throw new Exception("Invalid state for zig DC component");
}
var bit = Bytes.DecodeBit();
if (bit)
{
b[0] |= delta;
}
return;
}
int zig = zigStart;
if (EndOfBlockRun == 0)
{
for (; zig <= zigEnd; zig++)
{
bool done = false;
int z = 0;
var val = h.DecodeHuffman(Bytes);
int val0 = val >> 4;
int val1 = val & 0x0f;
switch (val1)
{
case 0:
if (val0 != 0x0f)
{
EndOfBlockRun = (ushort)(1 << val0);
if (val0 != 0)
{
var bits = Bytes.DecodeBits(val0);
EndOfBlockRun |= (ushort)bits;
}
done = true;
}
break;
case 1:
z = delta;
var bit = Bytes.DecodeBit();
if (!bit)
{
z = -z;
}
break;
default:
throw new Exception("unexpected Huffman code");
}
if (done)
{
break;
}
zig = refineNonZeroes(b, zig, zigEnd, val0, delta);
if (zig > zigEnd)
{
throw new Exception(string.Format("too many coefficients {0} > {1}", zig, zigEnd));
}
if (z != 0)
{
b[unzig[zig]] = z;
}
}
}
if (EndOfBlockRun > 0)
{
EndOfBlockRun--;
refineNonZeroes(b, zig, zigEnd, -1, delta);
}
}