disc: add some subcode infrastructure

BizHawk.Emulation/BizHawk.Emulation.csproj

@@ -163,10 +163,12 @@
     <Compile Include="Database\Database.cs" />
     <Compile Include="Disc\CCD_format.cs" />
     <Compile Include="Disc\CUE_format.cs" />
+    <Compile Include="Disc\Disc.API.cs" />
     <Compile Include="Disc\Disc.cs" />
     <Compile Include="Disc\DiscTOC.cs" />
     <Compile Include="Disc\ECM.cs" />
     <Compile Include="Disc\FFmpeg.cs" />
+    <Compile Include="Disc\Subcode.cs" />
     <Compile Include="Disc\TOC_format.cs" />
     <Compile Include="Interfaces\Base Implementations\Game.cs" />
     <Compile Include="Interfaces\Base Implementations\IPS.cs" />

BizHawk.Emulation/Disc/Disc.API.cs

@@ -0,0 +1,35 @@
+using System;
+
+//main apis for emulator core routine use
+
+namespace BizHawk.Disc
+{
+
+	public partial class Disc
+	{
+		//main API to read a 2352-byte LBA from a disc.
+		//this starts at the beginning of the disc (at the lead-in)
+		//so add 150 to get to a FAD-address in the user data area
+		public void ReadLBA(int lba, byte[] buffer, int offset)
+		{
+			if (lba < 150)
+			{
+				//lead-in area not supported yet
+				//in the future it will return something to mate with the 
+				//subchannel data which we will load or calculate from the TOC
+				return;
+			}
+
+			Sectors[lba - 150].Sector.Read(buffer, offset);
+		}
+
+		//main API to determine how many LBA sectors are available
+		public int LBACount { get { return Sectors.Count + 150; } }
+
+		//main api for reading the TOC from a disc
+		public DiscTOC ReadTOC()
+		{
+			return TOC;
+		}
+	}
+}

BizHawk.Emulation/Disc/Disc.cs

@@ -283,27 +283,6 @@ namespace BizHawk.Disc
 				}
 		}
 
-		//main api for reading a 2352-byte LBA from a disc.
-		//this starts at the beginning of the disc (at the lead-in)
-		//so add 150 to get to a FAD-address in the user data area
-		public void ReadLBA(int lba, byte[] buffer, int offset)
-		{
-			if (lba < 150) { 
-				//lead-in area not supported yet
-				//in the future it will return something to mate with the 
-				//subchannel data which we will load or calculate from the TOC
-				return;
-			}
-
-			Sectors[lba-150].Sector.Read(buffer, offset);
-		}
-
-		//main api for reading the TOC from a disc
-		public DiscTOC ReadTOC()
-		{
-			return TOC;
-		}
-
 		public static Disc FromCuePath(string cuePath)
 		{
 			var ret = new Disc();

BizHawk.Emulation/Disc/Subcode.cs

@@ -0,0 +1,119 @@
+using System;
+using System.Text;
+using System.Text.RegularExpressions;
+using System.IO;
+using System.Collections.Generic;
+
+//a decent little subcode reference
+//http://www.jbum.com/cdg_revealed.html
+
+namespace BizHawk.Disc
+{
+	public class SubcodeStream
+	{
+		Stream source;
+		long offset;
+		public SubcodeStream(Stream source, long offset)
+		{
+			this.source = source;
+			this.offset = offset;
+			cached_decoder = new SubcodePacketDecoder(cached_buffer, 0);
+		}
+		int channel = 0;
+		public char Channel
+		{
+			get { return (char)((7 - channel) + 'p'); }
+			set { channel = SubcodePacketDecoder.NormalizeChannel(value); }
+		}
+
+		long Position { get; set; }
+
+		int cached_addr = -1;
+		SubcodePacketDecoder cached_decoder = null;
+		byte[] cached_buffer = new byte[24];
+		public int ReadByte()
+		{
+			int subcode_addr = (int)Position;
+			int subcode_byte = subcode_addr & 1;
+			subcode_addr /= 2;
+			subcode_addr *= 24;
+			if (subcode_addr != cached_addr)
+			{
+				cached_decoder.Reset();
+				source.Position = offset + subcode_addr;
+				if (source.Read(cached_buffer, 0, 24) != 24)
+					return -1;
+				cached_addr = subcode_addr;
+			}
+			Position = Position + 1;
+			ushort val = cached_decoder.ReadChannel(channel);
+			val >>= (8 * subcode_byte);
+			val &= 0xFF;
+			return (int)val;
+		}
+	}
+
+	class SubcodePacketDecoder
+	{
+		internal static int NormalizeChannel(char channel)
+		{
+			int channum;
+			if (channel >= 'P' && channel <= 'W') channum = channel - 'P';
+			else if (channel >= 'p' && channel <= 'w') channum = (channel - 'p');
+			else throw new InvalidOperationException("invalid channel specified");
+			channum = 7 - channum;
+			return channum;
+		}
+
+		public void Reset()
+		{
+			cached = false;
+		}
+		byte[] buffer;
+		int offset;
+		public SubcodePacketDecoder(byte[] buffer, int offset)
+		{
+			this.buffer = buffer;
+			this.offset = offset;
+		}
+		byte command { get { return buffer[offset + 0]; } set { buffer[offset + 0] = value; } }
+		byte instruction { get { return buffer[offset + 1]; } set { buffer[offset + 1] = value; } }
+
+		public int parityQ_offset { get { return offset + 2; } }
+		public int data_offset { get { return offset + 4; } }
+		public int parityP_offset { get { return offset + 20; } }
+
+		public byte ReadData(int index)
+		{
+			return buffer[data_offset + index];
+		}
+
+		public ushort ReadChannel(char channel)
+		{
+			return ReadChannel(NormalizeChannel(channel));
+		}
+
+		bool cached;
+		ushort[] decoded_channels = new ushort[8];
+		public ushort ReadChannel(int channum)
+		{
+			if (!cached)
+			{
+				decoded_channels = new ushort[8];
+				for (int i = 0; i < 8; i++)
+					decoded_channels[i] = DecodeChannel(i);
+			}
+			return decoded_channels[channum];
+		}
+
+		ushort DecodeChannel(int channum)
+		{
+			int ret = 0;
+			for (int i = 0; i < 16; i++)
+			{
+				ret |= ((ReadData(i) >> channum) & 1) << i;
+			}
+			return (ushort)ret;
+		}
+	}
+}

DiscoHawk/DiscoHawk.cs

@@ -22,6 +22,21 @@ namespace BizHawk
 			//Console.WriteLine(disc.ReadTOC().DebugPrint());
 			//disc.DumpBin_2352("d:\\test.2352");
 
+			//test reading the subcode data. unfortunately we don't have lead-in subcode so we have no TOC
+			//using (FileStream fs = File.OpenRead("c:\\bof4.sub"))
+			//{
+			//    Disc.SubcodeStream stream = new Disc.SubcodeStream(fs, 0);
+			//    stream.Channel = 'q';
+			//    using (FileStream fsOut = File.OpenWrite("c:\\bof4.sub.q"))
+			//    {
+			//        for (; ; )
+			//        {
+			//            int ret = stream.ReadByte();
+			//            if (ret == -1) break;
+			//            fsOut.WriteByte((byte)ret);
+			//        }
+			//    }
+			//}
 
 		}
 	}