/// <summary>
/// Encrypts the <see cref="Data"/> according to the <see cref="Type"/> and <see cref="SubType"/>.
/// </summary>
public void WriteBlock(BinaryWriter bw)
{
var xk = new SCXorShift32(Key);
bw.Write(Key);
bw.Write((byte)((byte)Type ^ xk.Next()));
if (Type == SCTypeCode.Object)
{
bw.Write((uint)Data.Length ^ xk.Next32());
}
else if (Type == SCTypeCode.Array)
{
var entries = (uint)(Data.Length / SubType.GetTypeSize());
bw.Write(entries ^ xk.Next32());
bw.Write((byte)((byte)SubType ^ xk.Next()));
}
foreach (var b in Data)
{
bw.Write((byte)(b ^ xk.Next()));
}
}
/// <summary>
/// Reads a new <see cref="SCBlock"/> object from the <see cref="data"/>, determining the <see cref="Type"/> and <see cref="SubType"/> during read.
/// </summary>
/// <param name="data">Decrypted data</param>
/// <param name="offset">Offset the block is to be read from (modified to offset by the amount of bytes consumed).</param>
/// <returns>New object containing all info for the block.</returns>
public static SCBlock ReadFromOffset(byte[] data, ref int offset)
{
// Create block, parse its key.
var key = BitConverter.ToUInt32(data, offset);
offset += 4;
var xk = new SCXorShift32(key);
// Parse the block's type
//var block =
var type = (SCTypeCode)(data[offset++] ^ xk.Next());
switch (type)
{
case SCTypeCode.Bool1:
case SCTypeCode.Bool2:
case SCTypeCode.Bool3:
// Block types are empty, and have no extra data.
Debug.Assert(type != SCTypeCode.Bool3); // invalid type, haven't seen it used yet
return(new SCBlock(key, type));
case SCTypeCode.Object: // Cast raw bytes to Object
{
var num_bytes = BitConverter.ToUInt32(data, offset) ^ xk.Next32();
offset += 4;
var arr = new byte[num_bytes];
for (int i = 0; i < arr.Length; i++)
{
arr[i] = (byte)(data[offset++] ^ xk.Next());
}
return(new SCBlock(key, type, arr));
}
case SCTypeCode.Array: // Cast raw bytes to SubType[]
{
var num_entries = BitConverter.ToUInt32(data, offset) ^ xk.Next32();
offset += 4;
var sub = (SCTypeCode)(data[offset++] ^ xk.Next());
var num_bytes = num_entries * sub.GetTypeSize();
var arr = new byte[num_bytes];
for (int i = 0; i < arr.Length; i++)
{
arr[i] = (byte)(data[offset++] ^ xk.Next());
}
#if DEBUG
Debug.Assert(sub > SCTypeCode.Array || Array.TrueForAll(arr, z => z <= 1));
#endif
return(new SCBlock(key, arr, sub));
}
default: // Single Value Storage
{
var num_bytes = type.GetTypeSize();
var arr = new byte[num_bytes];
for (int i = 0; i < arr.Length; i++)
{
arr[i] = (byte)(data[offset++] ^ xk.Next());
}
return(new SCBlock(key, type, arr));
}
}
}
