/// <summary>
/// Ensures that the current tag lvt is an expected value
/// </summary>
/// <param name="lvt">The expected lvt value</param>
private void _ensureLVT(LVT lvt)
{
if (_lvt != lvt)
{
throw new InvalidTagException();
}
}
/// <summary>
/// Reads the next header from the input stream
/// if it hasn't already been read
/// </summary>
/// <returns>True if a header was read, false if the end of a stream was found</returns>
private bool _readHeader()
{
try
{
byte header = _reader.ReadByte();
_tagNumber = (byte)(header >> 4);
_isContext = (header & 0x08) > 0;
byte lvt = (byte)(header & 0x07);
if (_tagNumber == 0x0F)
_tagNumber = _reader.ReadByte();
if (!_isContext && _tagNumber == 0x01)
{
// boolean app tag, LVT is a value
_lvt = LVT.Value;
_value = lvt == 1 ? true : false;
}
else if (_isContext && lvt == 0x06)
{
// open tag, LVT is type
_lvt = LVT.Type;
_type = TagType.Open;
}
else if (_isContext && lvt == 0x07)
{
// close tag, LVT is type
_lvt = LVT.Type;
_type = TagType.Close;
}
else
{
// LVT is length
_lvt = LVT.Length;
if (lvt == 0x05)
{
_length = _reader.ReadByte();
if (_length == 254)
{
_length = _reader.ReadByte();
_length <<= 8;
_length |= _reader.ReadByte();
}
else if (_length == 255)
{
_length = _reader.ReadByte();
_length <<= 8;
_length |= _reader.ReadByte();
_length <<= 8;
_length = _reader.ReadByte();
_length <<= 8;
_length |= _reader.ReadByte();
}
}
else
_length = lvt;
}
_hasHeader = true;
return true;
}
catch(EndOfStreamException)
{
return false;
}
}
/// <summary>
/// Ensures that the current tag lvt is an expected value
/// </summary>
/// <param name="lvt">The expected lvt value</param>
private void _ensureLVT(LVT lvt)
{
if (_lvt != lvt)
throw new InvalidTagException();
}
/// <summary>
/// Reads the next header from the input stream
/// if it hasn't already been read
/// </summary>
/// <returns>True if a header was read, false if the end of a stream was found</returns>
private bool _readHeader()
{
try
{
byte header = _reader.ReadByte();
_tagNumber = (byte)(header >> 4);
_isContext = (header & 0x08) > 0;
byte lvt = (byte)(header & 0x07);
if (_tagNumber == 0x0F)
{
_tagNumber = _reader.ReadByte();
}
if (!_isContext && _tagNumber == 0x01)
{
// boolean app tag, LVT is a value
_lvt = LVT.Value;
_value = lvt == 1 ? true : false;
}
else if (_isContext && lvt == 0x06)
{
// open tag, LVT is type
_lvt = LVT.Type;
_type = TagType.Open;
}
else if (_isContext && lvt == 0x07)
{
// close tag, LVT is type
_lvt = LVT.Type;
_type = TagType.Close;
}
else
{
// LVT is length
_lvt = LVT.Length;
if (lvt == 0x05)
{
_length = _reader.ReadByte();
if (_length == 254)
{
_length = _reader.ReadByte();
_length <<= 8;
_length |= _reader.ReadByte();
}
else if (_length == 255)
{
_length = _reader.ReadByte();
_length <<= 8;
_length |= _reader.ReadByte();
_length <<= 8;
_length = _reader.ReadByte();
_length <<= 8;
_length |= _reader.ReadByte();
}
}
else
{
_length = lvt;
}
}
_hasHeader = true;
return(true);
}
catch (EndOfStreamException)
{
return(false);
}
}
