/// <summary>
/// Uses an integer long (32 bits) buffer to store the Huffman encoded bits
/// and sends them to outStream by the byte.
/// </summary>
private void bufferIt(EndianBinaryWriter writer, int code, int size)
{
int PutBuffer = code;
int PutBits = this.bufferPutBits;
PutBuffer &= (1 << size) - 1;
PutBits += size;
PutBuffer <<= 24 - PutBits;
PutBuffer |= this.bufferPutBuffer;
while (PutBits >= 8)
{
int c = (PutBuffer >> 16) & 0xFF;
writer.Write((byte)c);
// FF must be escaped
if (c == 0xFF)
{
writer.Write(0);
}
PutBuffer <<= 8;
PutBits -= 8;
}
this.bufferPutBuffer = PutBuffer;
this.bufferPutBits = PutBits;
}
public void FlushBuffer(EndianBinaryWriter writer)
{
int PutBuffer = this.bufferPutBuffer;
int PutBits = this.bufferPutBits;
while (PutBits >= 8)
{
int c = (PutBuffer >> 16) & 0xFF;
writer.Write((byte)c);
// FF must be escaped
if (c == 0xFF) writer.Write(0);
PutBuffer <<= 8;
PutBits -= 8;
}
if (PutBits > 0)
{
int c = (PutBuffer >> 16) & 0xFF;
writer.Write((byte)c);
}
}
/// <summary>
/// Figure F.16 - Reads the huffman code bit-by-bit.
/// </summary>
/// <param name="writer">The writer.</param>
/// <param name="zigzag">The zigzag.</param>
/// <param name="prec">The prec.</param>
/// <param name="DCcode">The D Ccode.</param>
/// <param name="ACcode">The A Ccode.</param>
/// <summary>
/// HuffmanBlockEncoder run length encodes and Huffman encodes the quantized data.
/// </summary>
internal void HuffmanBlockEncoder(EndianBinaryWriter writer, int[] zigzag, int prec, int DCcode, int ACcode)
{
int temp, temp2, nbits, k, r, i;
this.NumOfDCTables = 2;
this.NumOfACTables = 2;
// The DC portion
temp = temp2 = zigzag[0] - prec;
if (temp < 0)
{
temp = -temp;
temp2--;
}
nbits = 0;
while (temp != 0)
{
nbits++;
temp >>= 1;
}
// TODO: Why would this happen?
//if (nbits > 11) nbits = 11;
this.bufferIt(writer, this.DC_matrix[DCcode][nbits, 0], this.DC_matrix[DCcode][nbits, 1]);
// The arguments in bufferIt are code and size.
if (nbits != 0)
{
this.bufferIt(writer, temp2, nbits);
}
// The AC portion
r = 0;
for (k = 1; k < 64; k++)
{
if ((temp = zigzag[ZigZag.ZigZagMap[k]]) == 0)
{
r++;
}
else
{
while (r > 15)
{
this.bufferIt(writer, this.AC_matrix[ACcode][0xF0, 0], this.AC_matrix[ACcode][0xF0, 1]);
r -= 16;
}
temp2 = temp;
if (temp < 0)
{
temp = -temp;
temp2--;
}
nbits = 1;
while ((temp >>= 1) != 0)
{
nbits++;
}
i = (r << 4) + nbits;
this.bufferIt(writer, this.AC_matrix[ACcode][i, 0], this.AC_matrix[ACcode][i, 1]);
this.bufferIt(writer, temp2, nbits);
r = 0;
}
}
if (r > 0)
{
this.bufferIt(writer, this.AC_matrix[ACcode][0, 0], this.AC_matrix[ACcode][0, 1]);
}
}