/// <summary>
/// Provide the data for this chunk. (Not all chunks have data.)
/// </summary>
/// <param name="data">
/// The data for this chunk.
/// </param>
public void SetData(byte[] data)
{
this.m_data = data;
int length = this.m_data == null ? 0 : this.m_data.Length;
this.m_length = NetworkOrderBitConverter.GetBytes((uint)length);
uint crc = Crc32.UpdateCrc(0xffffffff, this.m_chunkType);
if (this.m_data != null)
{
crc = Crc32.UpdateCrc(crc, this.m_data);
}
crc ^= 0xffffffff;
this.m_crcBytes = NetworkOrderBitConverter.GetBytes(crc);
}
/// <summary>
/// Read bytes from this chunk.
/// </summary>
/// <param name="buffer">
/// Buffer into which to write bytes.
/// </param>
/// <param name="offset">
/// Offset in buffer at which to start
/// writing bytes.
/// </param>
/// <param name="count">
/// Maximum number of bytes to fetch.
/// </param>
/// <returns>
/// The number of bytes placed into the buffer. If the
/// buffer is larger than the amount of remaining data, this will
/// be less than count. Returns 0 to indicate that no data is left.
/// </returns>
public int Read(byte[] buffer, int offset, int count)
{
int dataLength = this.m_data == null ? 0 : this.m_data.Length;
if (this.m_data == null)
{
this.m_length = new byte[4];
this.m_crcBytes = NetworkOrderBitConverter.GetBytes(Crc32.Crc(this.m_chunkType));
}
int written = 0;
while (written < count)
{
int amount = 1;
if (this.position < 4)
{
amount = CopyUtilities.WriteAsMuchDataAsPossible(
buffer, offset + written, offset + count, this.m_length, this.position);
}
else if (this.position < 8)
{
amount = CopyUtilities.WriteAsMuchDataAsPossible(
buffer, offset + written, offset + count, this.m_chunkType, this.position - 4);
}
else if (this.position < (8 + dataLength))
{
amount = CopyUtilities.WriteAsMuchDataAsPossible(
buffer, offset + written, offset + count, this.m_data, this.position - 8);
}
else if (this.position < (12 + dataLength))
{
amount = CopyUtilities.WriteAsMuchDataAsPossible(
buffer, offset + written, offset + count, this.m_crcBytes, this.position - (8 + dataLength));
}
else
{
return(written);
}
this.position += amount;
written += amount;
}
return(count);
}