NESHawk: fix interaction between RDY and NMI/IRQ

src/BizHawk.Emulation.Cores/CPUs/MOS 6502X/Execute.cs

@@ -581,7 +581,10 @@ namespace BizHawk.Emulation.Cores.Components.M6502
 				}
 			}
 
-			Fetch1_Real();
+			mi = 0;
+			opcode = VOP_Fetch1_NoInterrupt;
+
+			Fetch1_Real();			
 		}
 
 		private void Fetch1_Real()

src/BizHawk.Emulation.Cores/Consoles/Nintendo/NES/APU.cs

@@ -746,7 +746,6 @@ namespace BizHawk.Emulation.Cores.Nintendo.NES
 							// when called due to empty bueffer while DMC running, there is no delay
 							nes.cpu.RDY = false;
 							nes.dmc_dma_exec = true;
-							nes.DMC_just_started = true;
 
 							if (fill_glitch_2)
 							{

src/BizHawk.Emulation.Cores/Consoles/Nintendo/NES/NES.Core.cs

@@ -447,15 +447,10 @@ namespace BizHawk.Emulation.Cores.Nintendo.NES
 		public byte oam_dma_byte;
 		public bool dmc_dma_exec = false;
 		public bool dmc_realign;
-		public bool IRQ_delay;
 		public bool reread_trigger;
 		public int do_the_reread_2002, do_the_reread_2007, do_the_reread_cont_1, do_the_reread_cont_2;
 		public int reread_opp_4016, reread_opp_4017;
 		public byte DB; //old data bus values from previous reads
-		// DMA's delay IRQ's by one cycle after finished, but allow them on the same cycle if just started
-		public bool DMC_just_started;
-		public bool OAM_just_started;
-		public bool ppu_nmi;
 
 		internal void RunCpuOne()
 		{
@@ -514,8 +509,6 @@ namespace BizHawk.Emulation.Cores.Nintendo.NES
 					apu.DMC_RDY_check = -1;
 				}
 
-				if (!dmc_dma_exec) { DMC_just_started = true; }
-				
 				cpu.RDY = false;
 				dmc_dma_exec = true;
 				apu.dmc_dma_countdown--;
@@ -586,37 +579,16 @@ namespace BizHawk.Emulation.Cores.Nintendo.NES
 			// dmc dma end
 			/////////////////////////////
 			apu.RunOneFirst();
-			
+
-			if (cpu.RDY && !IRQ_delay)
+			cpu.IRQ = _irq_apu || Board.IrqSignal;
+
+			// DMC was started in the APU, but in this case it only lasts 1 cycle and is then aborted, so put this here
+			// TODO: should this clock controllers?
+			if (apu.dmc.fill_glitch_2)
 			{
-				cpu.IRQ = _irq_apu || Board.IrqSignal;
+				apu.dmc_dma_countdown = -1;
-				if (ppu_nmi)
+				dmc_dma_exec = false;
-				{
+				apu.dmc.fill_glitch_2 = false;
-					cpu.NMI = ppu_nmi;
-					ppu_nmi = false;
-				}
-				
-			}
-			else if (OAM_just_started || DMC_just_started)
-			{			
-				cpu.IRQ = _irq_apu || Board.IrqSignal;
-				if (ppu_nmi)
-				{
-					cpu.NMI = ppu_nmi;
-					ppu_nmi = false;
-				}
-
-				OAM_just_started = false;
-				DMC_just_started = false;
-
-				// DMC was started in the APU, but in this case it only lasts 1 cycle and is then aborted, so put this here
-				// TODO: should this clock controllers?
-				if (apu.dmc.fill_glitch_2)
-				{
-					apu.dmc_dma_countdown = -1;
-					dmc_dma_exec = false;
-					apu.dmc.fill_glitch_2 = false;
-				}
 			}
 
 			cpu.ExecuteOne();
@@ -644,12 +616,9 @@ namespace BizHawk.Emulation.Cores.Nintendo.NES
 				reread_trigger = false;
 			}			
 
-			IRQ_delay = false;
-
 			if (!cpu.RDY && !dmc_dma_exec && !oam_dma_exec)
 			{
 				cpu.RDY = true;
-				IRQ_delay = true;
 			}
 		}
 
@@ -843,7 +812,6 @@ namespace BizHawk.Emulation.Cores.Nintendo.NES
 							oam_dma_exec = true;
 							cpu.RDY = false;
 							oam_dma_index = 0;
-							OAM_just_started = true;
 						}
 					}
 					break;

src/BizHawk.Emulation.Cores/Consoles/Nintendo/NES/NES.IStatable.cs

@@ -29,7 +29,6 @@ namespace BizHawk.Emulation.Cores.Nintendo.NES
 			ser.Sync(nameof(oam_dma_byte), ref oam_dma_byte);
 			ser.Sync(nameof(dmc_dma_exec), ref dmc_dma_exec);
 			ser.Sync(nameof(dmc_realign), ref dmc_realign);
-			ser.Sync(nameof(IRQ_delay), ref IRQ_delay);
 			ser.Sync(nameof(reread_trigger), ref reread_trigger);
 			ser.Sync(nameof(do_the_reread_2002), ref do_the_reread_2002);
 			ser.Sync(nameof(do_the_reread_2007), ref do_the_reread_2007);
@@ -37,9 +36,6 @@ namespace BizHawk.Emulation.Cores.Nintendo.NES
 			ser.Sync(nameof(do_the_reread_cont_2), ref do_the_reread_cont_2);
 			ser.Sync(nameof(reread_opp_4016), ref reread_opp_4016);
 			ser.Sync(nameof(reread_opp_4017), ref reread_opp_4017);
-			ser.Sync(nameof(OAM_just_started), ref OAM_just_started);
-			ser.Sync(nameof(DMC_just_started), ref DMC_just_started);
-			ser.Sync(nameof(ppu_nmi), ref ppu_nmi);
 
 			// VS related
 			ser.Sync("VS", ref _isVS);

src/BizHawk.Emulation.Cores/Consoles/Nintendo/NES/PPU.cs

@@ -423,7 +423,7 @@ namespace BizHawk.Emulation.Cores.Nintendo.NES
 					NMI_PendingInstructions--;
 					if (NMI_PendingInstructions <= 0)
 					{
-						nes.ppu_nmi = true;
+						nes.cpu.NMI = true;
 					}
 				}
 			}

src/BizHawk.Emulation.Cores/Consoles/Nintendo/NES/PPU.run.cs

@@ -175,7 +175,7 @@ namespace BizHawk.Emulation.Cores.Nintendo.NES
 			}
 			else if (ppur.status.cycle == (3 + NMI_offset) && ppur.status.sl == 241 + preNMIlines)
 			{
-				if (nmi_destiny) { nes.ppu_nmi = true; }
+				if (nmi_destiny) { nes.cpu.NMI = true; }
 				nes.Board.AtVsyncNmi();
 			}