/// <summary>
/// Decodes a field from data that has been field encoded.
/// </summary>
/// <param name="Data">The data to decode from.</param>
/// <param name="FieldType">The type of the field to decode.</param>
/// <param name="Value">A long that will contain the decoded value.</param>
/// <returns>1 for success, 0 for failure.</returns>
public int DecodeField(ref FieldEncodingData Data, byte FieldType, ref long Value)
{
long Prefix = 0, Width = 0;
if (ReadBits(ref Data, 1, ref Value) == 0)
{
return(0);
}
if (Value == 0)
{
return(1);
}
if (ReadBits(ref Data, 2, ref Prefix) == 0)
{
return(0);
}
Width = Data.FieldWidths[FieldType * 4 + Prefix];
if (ReadBits(ref Data, (byte)Width, ref Value) == 0)
{
return(0);
}
Value |= -(Value & 1L << (byte)(Width - 1));
return(1);
}
private int ReadBits(ref FieldEncodingData FieldData, byte Width, ref long Value)
{
while (FieldData.BitBufferCount < Width)
{
if (FieldData.ReadDataLength >= FieldData.EncodedDataLength)
return 0;
FieldData.BitBuffer <<= 8;
FieldData.BitBuffer |= FieldData.EncodedData[FieldData.FieldDataCounter];
FieldData.BitBufferCount += 8;
FieldData.ReadDataLength++;
}
Value = FieldData.BitBuffer >> (FieldData.BitBufferCount - Width);
Value &= (1L << Width) - 1;
FieldData.BitBufferCount -= Width;
return 1;
}
/// <summary>
/// Reads bits from data that has been field encoded.
/// </summary>
/// <param name="FieldData">The data to decode from.</param>
/// <param name="Width">The width of the field to encode (how many bits it occupies).</param>
/// <param name="Value">The value that will contain the decoded field.</param>
/// <returns>1 for success, 0 for failure.</returns>
private int ReadBits(ref FieldEncodingData FieldData, byte Width, ref long Value)
{
while (FieldData.BitBufferCount < Width)
{
if (FieldData.ReadDataLength >= FieldData.EncodedDataLength)
{
return(0);
}
FieldData.BitBuffer <<= 8;
FieldData.BitBuffer |= FieldData.EncodedData[FieldData.FieldDataCounter];
FieldData.BitBufferCount += 8;
FieldData.ReadDataLength++;
}
Value = FieldData.BitBuffer >> (FieldData.BitBufferCount - Width);
Value &= (1L << Width) - 1;
FieldData.BitBufferCount -= Width;
return(1);
}
public int DecodeField(ref FieldEncodingData Data, byte FieldType, ref long Value)
{
long Prefix = 0, Width = 0;
if(ReadBits(ref Data, 1, ref Value) == 0)
return 0;
if (Value == 0)
return 1;
if (ReadBits(ref Data, 2, ref Prefix) == 0)
return 0;
Width = Data.FieldWidths[FieldType * 4 + Prefix];
if(ReadBits(ref Data, (byte)Width, ref Value) == 0)
return 0;
Value |= -(Value & 1L << (byte)(Width - 1));
return 1;
}
