GG: Link support initial capability

BizHawk.Emulation.Cores/Consoles/Sega/GGHawkLink/GGHawkLink.IEmulator.cs

@@ -10,6 +10,8 @@ namespace BizHawk.Emulation.Cores.Sega.GGHawkLink
 
 		public ControllerDefinition ControllerDefinition => _controllerDeck.Definition;
 
+		public int L_NMI_CD, R_NMI_CD;
+
 		public bool FrameAdvance(IController controller, bool render, bool rendersound)
 		{
 			//Console.WriteLine("-----------------------FRAME-----------------------");
@@ -62,6 +64,33 @@ namespace BizHawk.Emulation.Cores.Sega.GGHawkLink
 			L.FrameAdvancePrep();
 			R.FrameAdvancePrep();
 
+			if (!_cableconnected)
+			{
+				if ((L.Port05 & 0x38) == 0x38)
+				{
+					L.Port05 |= 4;
+					L.Cpu.NonMaskableInterrupt = true;
+				}
+
+				if ((R.Port05 & 0x38) == 0x38)
+				{
+					R.Port05 |= 4;
+					R.Cpu.NonMaskableInterrupt = true;
+				}
+			}
+			else
+			{
+				if ((L.Port05 & 0x38) == 0x38)
+				{
+					L.Port05 &= 0xFB;
+				}
+
+				if ((R.Port05 & 0x38) == 0x38)
+				{
+					R.Port05 &= 0xFB;
+				}
+			}
+
 			int scanlinesPerFrame = 262;
 
 			L.Vdp.ScanLine = 0;
@@ -84,11 +113,92 @@ namespace BizHawk.Emulation.Cores.Sega.GGHawkLink
 					L.Cpu.ExecuteOne();
 					R.Cpu.ExecuteOne();
 
-					/*
+					// linking code
-					 * 
+					if (L.p3_write)
-					 *  Linking code goes here
+					{
-					 * 
+						L.p3_write = false;
-					 */
+
+						if (((L.Port05 & 0x38) == 0x38) && _cableconnected)
+						{
+							L.Port05 |= 1;
+
+							if ((R.Port05 & 0x38) == 0x38)
+							{
+								R.Port05 |= 2;
+								R.Port04 = L.Port03;
+								R_NMI_CD = 256;
+								//R.Cpu.NonMaskableInterrupt = true;
+							}
+						}					
+					}
+
+					if (L.p4_read)
+					{
+						L.p4_read = false;
+						L.Cpu.NonMaskableInterrupt = false;
+
+						if (((L.Port05 & 0x38) == 0x38) && _cableconnected)
+						{
+							L.Port05 &= 0xFD;
+
+							if ((R.Port05 & 0x38) == 0x38)
+							{
+								R.Port05 &= 0xFE;
+							}
+						}
+					}
+
+					if (R.p3_write)
+					{
+						R.p3_write = false;
+
+						if (((R.Port05 & 0x38) == 0x38) && _cableconnected)
+						{
+							R.Port05 |= 1;
+
+							if ((L.Port05 & 0x38) == 0x38)
+							{
+								L.Port05 |= 2;
+								L.Port04 = R.Port03;
+								L_NMI_CD = 256;
+								//L.Cpu.NonMaskableInterrupt = true;
+							}
+						}
+					}
+
+					if (R.p4_read)
+					{
+						R.p4_read = false;
+						R.Cpu.NonMaskableInterrupt = false;
+
+						if (((R.Port05 & 0x38) == 0x38) && _cableconnected)
+						{
+							R.Port05 &= 0xFD;
+
+							if ((L.Port05 & 0x38) == 0x38)
+							{
+								L.Port05 &= 0xFE;
+							}
+						}
+					}
+
+					if (L_NMI_CD > 0)
+					{
+						L_NMI_CD--;
+						if (L_NMI_CD == 0)
+						{
+							L.Cpu.NonMaskableInterrupt = true;
+						}
+					}
+
+					if (R_NMI_CD > 0)
+					{
+						R_NMI_CD--;
+						if (R_NMI_CD == 0)
+						{
+							R.Cpu.NonMaskableInterrupt = true;
+						}
+					}
 
 					L.PSG.generate_sound();
 					R.PSG.generate_sound();

BizHawk.Emulation.Cores/Consoles/Sega/GGHawkLink/GGHawkLink.IStatable.cs

@@ -59,6 +59,8 @@ namespace BizHawk.Emulation.Cores.Sega.GGHawkLink
 			ser.Sync(nameof(_cableconnected), ref _cableconnected);
 			ser.Sync(nameof(_cablediscosignal), ref _cablediscosignal);
 			ser.Sync(nameof(do_r_next), ref do_r_next);
+			ser.Sync(nameof(L_NMI_CD), ref L_NMI_CD);
+			ser.Sync(nameof(L_NMI_CD), ref R_NMI_CD);
 			_controllerDeck.SyncState(ser);
 		}
 	}

BizHawk.Emulation.Cores/Consoles/Sega/SMS/SMS.IStatable.cs

@@ -64,6 +64,8 @@ namespace BizHawk.Emulation.Cores.Sega.MasterSystem
 			ser.Sync(nameof(Bios_bank), ref Bios_bank);
 			ser.Sync(nameof(Port01), ref Port01);
 			ser.Sync(nameof(Port02), ref Port02);
+			ser.Sync(nameof(Port03), ref Port03);
+			ser.Sync(nameof(Port04), ref Port04);
 			ser.Sync(nameof(Port05), ref Port05);
 			ser.Sync(nameof(Port3E), ref Port3E);
 			ser.Sync(nameof(Port3F), ref Port3F);
@@ -74,6 +76,8 @@ namespace BizHawk.Emulation.Cores.Sega.MasterSystem
 			ser.Sync(nameof(cntr_rd_0), ref cntr_rd_0);
 			ser.Sync(nameof(cntr_rd_1), ref cntr_rd_1);
 			ser.Sync(nameof(cntr_rd_2), ref cntr_rd_2);
+			ser.Sync(nameof(p3_write), ref p3_write);
+			ser.Sync(nameof(p4_read), ref p4_read);
 			ser.Sync(nameof(stand_alone), ref stand_alone);
 			ser.Sync(nameof(disablePSG), ref disablePSG);
 			ser.Sync(nameof(sampleclock), ref sampleclock);

BizHawk.Emulation.Cores/Consoles/Sega/SMS/SMS.cs

@@ -245,8 +245,10 @@ namespace BizHawk.Emulation.Cores.Sega.MasterSystem
 		private int _frame = 0;
 
 		private byte Port01 = 0xFF;
-		private byte Port02 = 0xFF;
+		public byte Port02 = 0xFF;
-		private byte Port05 = 0x00;
+		public byte Port03 = 0x00;
+		public byte Port04 = 0xFF;
+		public byte Port05 = 0x00;
 		private byte Port3E = 0xAF;
 		private byte Port3F = 0xFF;
 		private byte PortDE = 0x00;
@@ -260,6 +262,8 @@ namespace BizHawk.Emulation.Cores.Sega.MasterSystem
 		public byte cntr_rd_1;
 		public byte cntr_rd_2;
 		public bool stand_alone = true;
+		public bool p3_write;
+		public bool p4_read;
 
 		public DisplayType Region { get; set; }
 
@@ -345,8 +349,8 @@ namespace BizHawk.Emulation.Cores.Sega.MasterSystem
 					case 0x00: if (stand_alone) { return ReadPort0(); } else { _lagged = false; return cntr_rd_0; }
 					case 0x01: return Port01;
 					case 0x02: return Port02;
-					case 0x03: return 0x00;
+					case 0x03: return Port03;
-					case 0x04: return 0xFF;
+					case 0x04: p4_read = true; return Port04;
 					case 0x05: return Port05;
 					case 0x06: return 0xFF;
 					case 0x3E: return Port3E;
@@ -388,7 +392,9 @@ namespace BizHawk.Emulation.Cores.Sega.MasterSystem
 				{
 					case 0x01: Port01 = value; break;
 					case 0x02: Port02 = value; break;
-					case 0x05: Port05 = value; break;
+					case 0x03: p3_write = true; Port03 = value; break;
+					case 0x04: /*Port04 = value*/; break; // receive port, not sure what writing does
+					case 0x05: Port05 = (byte)(value & 0xF8); break;
 					case 0x06: PSG.Set_Panning(value); break;
 					case 0x3E: Port3E = value; break;
 					case 0x3F: Port3F = value; break;