More work

src/BizHawk.Emulation.Cores/Consoles/Watara/SuperVision/ASIC.cs

@@ -48,7 +48,12 @@ namespace BizHawk.Emulation.Cores.Consoles.SuperVision
 		public int CLOCK_WIDTH => 
 			((_regs[R_LCD_X_SIZE] & 0xFC)	// topmost 6 bits of the X Size register
 			+ 4)                            // line latch pulse
-			* 6;							// 6 clocks per pixel
+			* 6;                            // 6 clocks per pixel
+
+		/// <summary>
+		/// Y offset modifier used with Y_Scroll to determine the VRAM pointer
+		/// </summary>
+		public int Y_OFFSET => _regs[R_LCD_X_SIZE] > 0xC0 ? 0x30 : 0x60;
 
 		/// <summary>
 		/// Number of scanlines in a field
@@ -82,6 +87,8 @@ namespace BizHawk.Emulation.Cores.Consoles.SuperVision
 		private int _lineCounter;
 		private int _field;
 		private ushort _vramByteBuffer;
+		private int _vramPointer;
+		private int _vramStartAddress;
 
 		/// <summary>
 		/// ASIC is clocked at the same rate as the CPU
@@ -106,8 +113,29 @@ namespace BizHawk.Emulation.Cores.Consoles.SuperVision
 					// there is no DMA on this cycle so CPU can run freely
 					_sv._cpu.RDY = true;
 
+					bool lineEnd = _byteCounter == CLOCK_WIDTH - 1;
+					bool fieldEnd = _lineCounter == LINE_HEIGHT && lineEnd && _field == 0;
+					bool frameEnd = _lineCounter == LINE_HEIGHT && lineEnd && _field == 1;
+
+					// vram pointer
+					if (fieldEnd)
+					{
+						// Y_Scroll offset added to the VRAM pointer at the start of the field (could be frame)
+						_vramStartAddress = (_regs[R_Y_SCROLL] * Y_OFFSET) & 0x1FFF;
+
+						if (_vramStartAddress == 0x1FE0)
+							_vramStartAddress = 0;
+					}
+
+					if (_byteCounter == 0)
+					{
+						// new scanline
+						_vramPointer = _vramStartAddress + (_regs[R_X_SCROLL] >> 2);
+					}
+
 					// ASIC reads a byte from VRAM					
-					byte data = 0xff; //todo
+					byte data = _sv.ReadVRAM((ushort) _vramPointer);
+					_vramPointer++;
 
 					// shift the last read byte in the buffer and add the new byte to the start
 					_vramByteBuffer = (ushort) ((_vramByteBuffer << 8) | data);
@@ -121,10 +149,7 @@ namespace BizHawk.Emulation.Cores.Consoles.SuperVision
 					// Field1:	bits 1-3-5-7
 					byte lData = _field == 0
 						? (byte) ((b & 0b0000_0001) | ((b & 0b0000_0100) >> 1) | ((b & 0b0001_0000) >> 2) | ((b & 0b0100_0000) >> 3))
-						: (byte) ((b & 0b0000_0010) >> 1 | ((b & 0b0000_1000) >> 2) | ((b & 0b0010_0000) >> 3) | ((b & 0b1000_0000) >> 4));
-
-					bool lineEnd = _byteCounter == CLOCK_WIDTH - 1;
-					bool frameEnd = _lineCounter == LINE_HEIGHT && lineEnd && _field == 1;
+						: (byte) ((b & 0b0000_0010) >> 1 | ((b & 0b0000_1000) >> 2) | ((b & 0b0010_0000) >> 3) | ((b & 0b1000_0000) >> 4));					
 
 					// send 1/2 byte to the LCD
 					Screen.PixelClock(lData, _field, lineEnd, frameEnd);
@@ -137,6 +162,11 @@ namespace BizHawk.Emulation.Cores.Consoles.SuperVision
 						_byteCounter = 0;
 						_lineCounter++;
 
+						// setup start address
+						_vramStartAddress += Y_OFFSET & 0x1FFF;
+						if (_vramStartAddress == 0x1FE0)
+							_vramStartAddress = 0;
+
 						if (_lineCounter == LINE_HEIGHT)
 						{
 							// end of field
@@ -395,7 +425,7 @@ namespace BizHawk.Emulation.Cores.Consoles.SuperVision
 					Screen.DisplayEnable = value.Bit(3);
 
 					// banking
-					_sv.BankSelect = value >> 5;
+					_sv.BankSelect = (value >> 5);
 
 					// writing to this register resets the LCD rendering system and makes it start rendering from the upper left corner, regardless of the bit pattern.
 					Screen.ResetPosition();
@@ -546,6 +576,8 @@ namespace BizHawk.Emulation.Cores.Consoles.SuperVision
 			ser.Sync(nameof(_lineCounter), ref _lineCounter);
 			ser.Sync(nameof(_field), ref _field);
 			ser.Sync(nameof(_vramByteBuffer), ref _vramByteBuffer);
+			ser.Sync(nameof(_vramPointer), ref _vramPointer);
+			ser.Sync(nameof(_vramStartAddress), ref _vramStartAddress);
 			Screen.SyncState(ser);
 
 			ser.EndSection();

src/BizHawk.Emulation.Cores/Consoles/Watara/SuperVision/Cart/SVCart.cs

@@ -10,6 +10,8 @@ namespace BizHawk.Emulation.Cores.Consoles.SuperVision
 		/// </summary>
 		private byte[] _rom = new byte[0x20000];
 
+		public int CartROMSize => _rom.Length;
+
 		public SVCart(byte[] rom)
 		{
 			if (_rom.Length != rom.Length)

src/BizHawk.Emulation.Cores/Consoles/Watara/SuperVision/Memory.cs

@@ -11,12 +11,18 @@ namespace BizHawk.Emulation.Cores.Consoles.SuperVision
 		/// <summary>
 		/// 8K of VRAM which the CPU can access with 0 wait states
 		/// </summary>
-		public byte[] VRAM = new byte[0x2000];		
+		public byte[] VRAM = new byte[0x2000];
 
 		/// <summary>
 		/// Bank select index
 		/// </summary>
-		public int BankSelect;
+		public int BankSelect
+		{
+			get { return _bankSelect % (_cartridge.CartROMSize / 0x4000); }
+			set { _bankSelect = value; }
+		}
+		private int _bankSelect;
+
 
 		/// <summary>
 		/// True when the CPU is accessing memory
@@ -63,6 +69,7 @@ namespace BizHawk.Emulation.Cores.Consoles.SuperVision
 					// 0: first 16k
 					// 1: 2nd 16k
 					// 2: 3rd 16k
+					// etc..
 					result = _cartridge.ReadByte((ushort) ((address % 0x4000) + (BankSelect * 0x4000)));
 					break;
 
@@ -71,7 +78,7 @@ namespace BizHawk.Emulation.Cores.Consoles.SuperVision
 				case 6:
 				case 7:
 					// fixed to the last 16K in the cart address space
-					result = _cartridge.ReadByte((ushort) ((address % 0x4000) + (3 * 0x4000)));
+					result = _cartridge.ReadByte((ushort) ((address % 0x4000) + (_cartridge.CartROMSize - 0x4000)));
 					break;
 			}
 
@@ -115,6 +122,7 @@ namespace BizHawk.Emulation.Cores.Consoles.SuperVision
 					// 0: first 16k
 					// 1: 2nd 16k
 					// 2: 3rd 16k
+					// etc..
 					_cartridge.WriteByte((ushort) ((address % 0x4000) + (BankSelect * 0x4000)), value);
 					break;
 
@@ -123,9 +131,19 @@ namespace BizHawk.Emulation.Cores.Consoles.SuperVision
 				case 6: 
 				case 7:
 					// fixed to the last 16K in the cart address space
-					_cartridge.WriteByte((ushort) ((address % 0x4000) + (3 * 0x4000)), value);
+					_cartridge.WriteByte((ushort) ((address % 0x4000) + (_cartridge.CartROMSize - 0x4000)), value);
 					break;
 			}			
 		}
+
+		/// <summary>
+		/// ASIC is connected directly to VRAM
+		/// 8bit data bus
+		/// 12bit addr bus
+		/// </summary>
+		public byte ReadVRAM(ushort address)
+		{
+			return VRAM[address & 0x0FFF];
+		}
 	}
 }

src/BizHawk.Emulation.Cores/Consoles/Watara/SuperVision/SuperVision.Statable.cs

@@ -7,7 +7,7 @@ namespace BizHawk.Emulation.Cores.Consoles.SuperVision
 		private void SyncState(Serializer ser)
 		{
 			ser.BeginSection("SuperVision");
-			ser.Sync(nameof(BankSelect), ref BankSelect);
+			ser.Sync(nameof(BankSelect), ref _bankSelect);
 
 			ser.Sync(nameof(_frameClock), ref _frameClock);
 			ser.Sync(nameof(_frame), ref _frame);