/// <summary>
/// Populates the current instance with the contents of the
/// raw ID3v2 frame.
/// </summary>
/// <param name="data">
/// A <see cref="ByteVector" /> object containing the raw
/// extended header structure.
/// </param>
/// <param name="version">
/// A <see cref="byte" /> value indicating the ID3v2 version.
/// </param>
protected void Parse(ByteVector data, byte version)
{
if (data == null)
{
throw new ArgumentNullException("data");
}
size = (version == 3 ? 4u : 0u) + SynchData.ToUInt(data.Mid(0, 4));
}
/// <summary>
/// Constructs and initializes a new instance of <see
/// cref="Header" /> by reading it from raw header data.
/// </summary>
/// <param name="data">
/// A <see cref="ByteVector" /> object containing the raw
/// data to build the new instance from.
/// </param>
/// <exception cref="ArgumentNullException">
/// <paramref name="data" /> is <see langword="null" />.
/// </exception>
/// <exception cref="CorruptFileException">
/// <paramref name="data" /> is smaller than <see
/// cref="Size" />, does not begin with <see
/// cref="FileIdentifier" />, contains invalid flag data,
/// or contains invalid size data.
/// </exception>
public Header(ByteVector data)
{
if (data == null)
{
throw new ArgumentNullException("data");
}
if (data.Count < Size)
{
throw new CorruptFileException(
"Provided data is smaller than object size.");
}
if (!data.StartsWith(FileIdentifier))
{
throw new CorruptFileException(
"Provided data does not start with the file identifier");
}
major_version = data [3];
revision_number = data [4];
flags = (HeaderFlags)data [5];
if (major_version == 2 && ((int)flags & 127) != 0)
{
throw new CorruptFileException(
"Invalid flags set on version 2 tag.");
}
if (major_version == 3 && ((int)flags & 15) != 0)
{
throw new CorruptFileException(
"Invalid flags set on version 3 tag.");
}
if (major_version == 4 && ((int)flags & 7) != 0)
{
throw new CorruptFileException(
"Invalid flags set on version 4 tag.");
}
for (int i = 6; i < 10; i++)
{
if (data [i] >= 128)
{
throw new CorruptFileException(
"One of the bytes in the header was greater than the allowed 128.");
}
}
tag_size = SynchData.ToUInt(data.Mid(6, 4));
}
/// <summary>
/// Constructs and initializes a new instance of <see
/// cref="FrameHeader" /> by reading it from raw header data
/// of a specified version.
/// </summary>
/// <param name="data">
/// A <see cref="ByteVector" /> object containing the raw
/// data to build the new instance from.
/// </param>
/// <param name="version">
/// A <see cref="byte" /> value containing the ID3v2 version
/// with which the data in <paramref name="data" /> was
/// encoded.
/// </param>
/// <remarks>
/// If the data size is smaller than the size of a full
/// header, the data is just treated as a frame identifier
/// and the remaining values are zeroed.
/// </remarks>
/// <exception cref="ArgumentNullException">
/// <paramref name="data" /> is <see langword="null" />.
/// </exception>
/// <exception cref="CorruptFileException">
/// <paramref name="data" /> is smaller than the size of a
/// frame identifier or <paramref name="version" /> is less
/// than 2 or more than 4.
/// </exception>
public FrameHeader(ByteVector data, byte version)
{
if (data == null)
{
throw new ArgumentNullException("data");
}
flags = 0;
frame_size = 0;
if (version < 2 || version > 4)
{
throw new CorruptFileException(
"Unsupported tag version.");
}
if (data.Count < (version == 2 ? 3 : 4))
{
throw new CorruptFileException(
"Data must contain at least a frame ID.");
}
switch (version)
{
case 2:
// Set the frame ID -- the first three bytes
frame_id = ConvertId(data.Mid(0, 3), version,
false);
// If the full header information was not passed
// in, do not continue to the steps to parse the
// frame size and flags.
if (data.Count < 6)
{
return;
}
frame_size = data.Mid(3, 3).ToUInt();
return;
case 3:
// Set the frame ID -- the first four bytes
frame_id = ConvertId(data.Mid(0, 4), version,
false);
// If the full header information was not passed
// in, do not continue to the steps to parse the
// frame size and flags.
if (data.Count < 10)
{
return;
}
// Store the flags internally as version 2.4.
frame_size = data.Mid(4, 4).ToUInt();
flags = (FrameFlags)(
((data [8] << 7) & 0x7000) |
((data [9] >> 4) & 0x000C) |
((data [9] << 1) & 0x0040));
return;
case 4:
// Set the frame ID -- the first four bytes
frame_id = new ReadOnlyByteVector(
data.Mid(0, 4));
// If the full header information was not passed
// in, do not continue to the steps to parse the
// frame size and flags.
if (data.Count < 10)
{
return;
}
frame_size = SynchData.ToUInt(data.Mid(4, 4));
flags = (FrameFlags)data.Mid(8, 2).ToUShort();
return;
default:
throw new CorruptFileException(
"Unsupported tag version.");
}
}