private void ParseBaselineDataInterleaved()
{
// Interleaved
int mcu = 0;
int mcusPerColumn = this.frame.McusPerColumn;
int mcusPerLine = this.frame.McusPerLine;
for (int j = 0; j < mcusPerColumn; j++)
{
for (int i = 0; i < mcusPerLine; i++)
{
// Scan an interleaved mcu... process components in order
for (int k = 0; k < this.componentsLength; k++)
{
int order = this.frame.ComponentOrder[k];
JpegComponent component = this.components[order];
ref HuffmanTable dcHuffmanTable = ref this.dcHuffmanTables[component.DCHuffmanTableId];
ref HuffmanTable acHuffmanTable = ref this.acHuffmanTables[component.ACHuffmanTableId];
ref short fastACRef = ref this.fastACTables.GetAcTableReference(component);
int h = component.HorizontalSamplingFactor;
int v = component.VerticalSamplingFactor;
int mcuRow = mcu / mcusPerLine;
// Scan out an mcu's worth of this component; that's just determined
// by the basic H and V specified for the component
for (int y = 0; y < v; y++)
{
int blockRow = (mcuRow * v) + y;
Span <Block8x8> blockSpan = component.SpectralBlocks.GetRowSpan(blockRow);
for (int x = 0; x < h; x++)
{
if (this.eof)
{
return;
}
int mcuCol = mcu % mcusPerLine;
int blockCol = (mcuCol * h) + x;
this.DecodeBlockBaseline(
component,
ref blockSpan[blockCol],
ref dcHuffmanTable,
ref acHuffmanTable,
ref fastACRef);
}
}
}
private unsafe void ParseBaselineDataInterleaved()
{
// Interleaved
int mcu = 0;
int mcusPerColumn = this.frame.McusPerColumn;
int mcusPerLine = this.frame.McusPerLine;
// Pre-derive the huffman table to avoid in-loop checks.
for (int i = 0; i < this.componentsLength; i++)
{
int order = this.frame.ComponentOrder[i];
JpegComponent component = this.components[order];
ref HuffmanTable dcHuffmanTable = ref this.dcHuffmanTables[component.DCHuffmanTableId];
ref HuffmanTable acHuffmanTable = ref this.acHuffmanTables[component.ACHuffmanTableId];
public unsafe int DecodeHuffman(ref HuffmanTable h)
{
this.CheckBits();
int v = this.PeekBits(JpegConstants.Huffman.LookupBits);
int symbol = h.LookaheadValue[v];
int size = h.LookaheadSize[v];
if (size == JpegConstants.Huffman.SlowBits)
{
ulong x = this.data << (JpegConstants.Huffman.RegisterSize - this.remainingBits);
while (x > h.MaxCode[size])
{
size++;
}
v = (int)(x >> (JpegConstants.Huffman.RegisterSize - size));
symbol = h.Values[(h.ValOffset[size] + v) & 0xFF];
}
this.remainingBits -= size;
return(symbol);
}
/// <summary>
/// Derives a lookup table for fast AC entropy scan decoding.
/// This can happen multiple times during progressive decoding but always outside mcu loops.
/// </summary>
/// <param name="huffmanTable">The AC Huffman table.</param>
public void Derive(ref HuffmanTable huffmanTable)
{
const int FastBits = ScanDecoder.FastBits;
ref short fastACRef = ref this.Lookahead[0];