BizHawk/BizHawk.Emulation.Cores/Computers/Commodore64/Media/G64.cs

using System;
using System.Collections.Generic;
using System.IO;
using System.Linq;

namespace BizHawk.Emulation.Cores.Computers.Commodore64.Media
{
	public static class G64
	{
		public static Disk Read(byte[] source)
		{
			var mem = new MemoryStream(source);
			var reader = new BinaryReader(mem);
			var id = new string(reader.ReadChars(8));
            var trackDatas = new List<byte[]>();
            var trackLengths = new List<int>();
            var trackNumbers = new List<int>();
            var trackDensities = new List<int>();

            if (id == @"GCR-1541")
			{

				reader.ReadByte(); //version
				int trackCount = reader.ReadByte();
				reader.ReadInt16(); //max track size in bytes

                var trackOffsetTable = new int[trackCount];
                var trackSpeedTable = new int[trackCount];

                for (var i = 0; i < trackCount; i++)
					trackOffsetTable[i] = reader.ReadInt32();

				for (var i = 0; i < trackCount; i++)
					trackSpeedTable[i] = reader.ReadInt32();

				for (var i = 0; i < trackCount; i++)
				{
					if (trackOffsetTable[i] > 0)
					{
						mem.Position = trackOffsetTable[i];
						int trackLength = reader.ReadInt16();
						var trackData = reader.ReadBytes(trackLength);

                        trackDatas.Add(trackData);
                        trackLengths.Add(trackLength * 8);
                        trackDensities.Add(trackSpeedTable[i]);
                        trackNumbers.Add(i);
					}
				}

			    if (trackSpeedTable.Any(ts => ts > 3 || ts < 0))
			    {
			        throw new Exception("Byte-level speeds are not yet supported in the G64 loader.");
			    }

                return new Disk(trackDatas, trackNumbers, trackDensities, trackLengths, 84);
			}

            return new Disk(84);
		}
    }
}