/// <summary>
/// Creates and initializes an array of <see cref="OrigHuffmanTree" /> instances of size <see cref="NumberOfTrees" />
/// </summary>
/// <returns>An array of <see cref="OrigHuffmanTree" /> instances representing the Huffman tables</returns>
public static OrigHuffmanTree[] CreateHuffmanTrees()
{
OrigHuffmanTree[] result = new OrigHuffmanTree[NumberOfTrees];
for (int i = 0; i < MaxTc + 1; i++)
{
for (int j = 0; j < MaxTh + 1; j++)
{
result[(i * ThRowSize) + j].Init();
}
}
return(result);
}
/// <summary>
/// Extracts the next Huffman-coded value from the bit-stream into result, decoded according to the given value.
/// </summary>
/// <param name="huffmanTree">The huffman value</param>
/// <param name="result">The decoded <see cref="byte" /></param>
/// <returns>The <see cref="OrigDecoderErrorCode"/></returns>
public OrigDecoderErrorCode DecodeHuffmanUnsafe(ref OrigHuffmanTree huffmanTree, out int result)
{
result = 0;
if (huffmanTree.Length == 0)
{
DecoderThrowHelper.ThrowImageFormatException.UninitializedHuffmanTable();
}
if (this.Bits.UnreadBits < 8)
{
this.LastErrorCode = this.Bits.Ensure8BitsUnsafe(ref this);
if (this.LastErrorCode == OrigDecoderErrorCode.NoError)
{
int lutIndex = (this.Bits.Accumulator >> (this.Bits.UnreadBits - OrigHuffmanTree.LutSizeLog2)) & 0xFF;
int v = huffmanTree.Lut[lutIndex];
if (v != 0)
{
int n = (v & 0xFF) - 1;
this.Bits.UnreadBits -= n;
this.Bits.Mask >>= n;
result = v >> 8;
return(this.LastErrorCode);
}
}
else
{
this.UnreadByteStuffedByte();
return(this.LastErrorCode);
}
}
int code = 0;
for (int i = 0; i < OrigHuffmanTree.MaxCodeLength; i++)
{
if (this.Bits.UnreadBits == 0)
{
this.LastErrorCode = this.Bits.EnsureNBitsUnsafe(1, ref this);
if (this.HasError)
{
return(this.LastErrorCode);
}
}
if ((this.Bits.Accumulator & this.Bits.Mask) != 0)
{
code |= 1;
}
this.Bits.UnreadBits--;
this.Bits.Mask >>= 1;
if (code <= huffmanTree.MaxCodes[i])
{
result = huffmanTree.GetValue(code, i);
return(this.LastErrorCode = OrigDecoderErrorCode.NoError);
}
code <<= 1;
}
// Unrecoverable error, throwing:
DecoderThrowHelper.ThrowImageFormatException.BadHuffmanCode();
// DUMMY RETURN! C# doesn't know we have thrown an exception!
return(OrigDecoderErrorCode.NoError);
}
