C64: Fix voume based audio sampling, fix some state bugs

BizHawk.Emulation.Cores/Computers/Commodore64/C64.IMemoryDomains.cs

@@ -34,7 +34,7 @@ namespace BizHawk.Emulation.Cores.Computers.Commodore64
 				});
 			}
 
-			if (tapeDriveEnabled)
+			if (tapeDriveEnabled && (_board.TapeDrive.TapeDataDomain != null))
 			{
 				domains.AddRange(new[]
 				{

BizHawk.Emulation.Cores/Computers/Commodore64/Cassette/TapeDrive.cs

@@ -32,7 +32,8 @@ namespace BizHawk.Emulation.Cores.Computers.Commodore64.Cassette
 
 		public override void SyncState(Serializer ser)
 		{
-			_tape.SyncState(ser);
+
+			if (_tape != null) { _tape.SyncState(ser); }
 		}
 
 		public void Insert(Tape tape)
@@ -46,6 +47,19 @@ namespace BizHawk.Emulation.Cores.Computers.Commodore64.Cassette
 		}
 
 		// Exposed for memory domains, should not be used for actual emulation implementation
-		public override byte[] TapeDataDomain => _tape.TapeDataDomain;
+		public override byte[] TapeDataDomain 
+		{
+			get
+			{
+				if (_tape != null)
+				{
+					return _tape.TapeDataDomain;
+				}
+				else
+				{
+					return null;
+				}
+			}
+		}		
 	}
 }

BizHawk.Emulation.Cores/Computers/Commodore64/MOS/Sid.Registers.cs

@@ -138,12 +138,13 @@
 
 					// we want to only flush the filter when the filter is actually changed, that way
 					// the FFT will not be impacted by small sample sizes from other changes
-					if (addr == 15 || addr == 16 || addr==17)
+					if ((addr == 0x15) || (addr == 0x16) || (addr == 0x17))
 					{
 						Flush(true);
 					}
-					else if (addr==18)
+					else if (addr == 0x18)
 					{
+						
 						// note: we only want to flush the filter here if the filter components are changing
 						bool temp1 = (val & 0x10) != 0;
 						bool temp2 = (val & 0x20) != 0;

BizHawk.Emulation.Cores/Computers/Commodore64/MOS/Sid.SoundProvider.cs

@@ -49,8 +49,8 @@ namespace BizHawk.Emulation.Cores.Computers.Commodore64.MOS
 			{
 				_mixer = _outputBuffer_not_filtered[i] + _outputBuffer_filtered[i];
 				_mixer = _mixer >> 7;
-				_mixer = (_mixer * _volume) >> 4;
-				_mixer -= _volume << 8;
+				_mixer = (_mixer * _volume_at_sample_time[i]) >> 4;
+				_mixer -= _volume_at_sample_time[i] << 8;
 
 				if (_mixer > 0x7FFF)
 				{

BizHawk.Emulation.Cores/Computers/Commodore64/MOS/Sid.cs

@@ -41,6 +41,7 @@ namespace BizHawk.Emulation.Cores.Computers.Commodore64.MOS
 		private short[] _outputBuffer;
 		private int[] _outputBuffer_filtered;
 		private int[] _outputBuffer_not_filtered;
+		private int[] _volume_at_sample_time;
 		private int _outputBufferIndex;
 		private int filter_index;
 		private int last_filtered_value;
@@ -93,6 +94,7 @@ namespace BizHawk.Emulation.Cores.Computers.Commodore64.MOS
 
 			_outputBuffer_filtered = new int[sampleRate];
 			_outputBuffer_not_filtered = new int[sampleRate];
+			_volume_at_sample_time = new int[sampleRate];
 		}
 
 		// ------------------------------------
@@ -190,6 +192,7 @@ namespace BizHawk.Emulation.Cores.Computers.Commodore64.MOS
 					{
 						_outputBuffer_not_filtered[_outputBufferIndex] = temp_not_filtered;
 						_outputBuffer_filtered[_outputBufferIndex] = temp_filtered;
+						_volume_at_sample_time[_outputBufferIndex] = _volume;
 						_outputBufferIndex++;
 					}
 				}