[NES] work on sound, improve square waves muchly, add 6502 IRQ signal, make add some infrastructure to keep from buffering samples while core is silenced.

BizHawk.Emulation/CPUs/MOS 6502/Execute.cs

@@ -22,6 +22,10 @@ namespace BizHawk.Emulation.CPUs.M6502
                    TriggerException(ExceptionType.NMI);
                    NMI = false;
                }
+               if (IRQ && !FlagI)
+               {
+                   TriggerException(ExceptionType.IRQ);
+               }
 
                 if(debug) Console.WriteLine(State());
 
@@ -1201,9 +1205,7 @@ FlagT = true;// this seems wrong
                         PendingCycles -= 7; TotalExecutedCycles += 7;
                         break;
                     default:
-                        //throw new Exception(String.Format("Unhandled opcode: {0:X2}", opcode));
+                        throw new Exception(String.Format("Unhandled opcode: {0:X2}", opcode));
-						//Console.WriteLine(String.Format("Unhandled opcode: {0:X2}", opcode));
-						break;
                 }
             }
         }

BizHawk.Emulation/CPUs/MOS 6502/MOS6502.cs

@@ -64,10 +64,11 @@ namespace BizHawk.Emulation.CPUs.M6502
 		private const ushort NMIVector = 0xFFFA;
 		private const ushort ResetVector = 0xFFFC;
 		private const ushort BRKVector = 0xFFFE;
+		private const ushort IRQVector = 0xFFFE;
 
 		enum ExceptionType
 		{
-			BRK, NMI
+			BRK, NMI, IRQ
 		}
 
 		void TriggerException(ExceptionType type)
@@ -80,10 +81,19 @@ namespace BizHawk.Emulation.CPUs.M6502
 			WriteMemory((ushort)(S-- + 0x100), P);
 			P = oldP;
 			FlagI = true;
-			if (type == ExceptionType.NMI)
+			switch (type)
-				PC = ReadWord(NMIVector);
+			{
-			else
+				case ExceptionType.NMI:
-				PC = ReadWord(BRKVector);
+					PC = ReadWord(NMIVector);
+					break;
+				case ExceptionType.IRQ:
+					PC = ReadWord(IRQVector);
+					break;
+				case ExceptionType.BRK:
+					PC = ReadWord(BRKVector);
+					break;
+				default: throw new Exception();
+			}
 			PendingCycles -= 7;
 		}
 
@@ -96,8 +106,7 @@ namespace BizHawk.Emulation.CPUs.M6502
         public ushort PC;
         public byte S;
 
-        // TODO IRQ, NMI functions
+        public bool IRQ;
-        public bool Interrupt;
         public bool NMI;
 
 		public void SaveStateText(TextWriter writer)
@@ -110,7 +119,7 @@ namespace BizHawk.Emulation.CPUs.M6502
 			writer.WriteLine("PC {0:X4}", PC);
 			writer.WriteLine("S {0:X2}", S);
 			writer.WriteLine("NMI {0}", NMI);
-			writer.WriteLine("Interrupt {0}", Interrupt);
+			writer.WriteLine("IRQ {0}", IRQ);
 			writer.WriteLine("TotalExecutedCycles {0}", TotalExecutedCycles);
 			writer.WriteLine("PendingCycles {0}", PendingCycles);
 			writer.WriteLine("[/MOS6502]\n");
@@ -137,8 +146,8 @@ namespace BizHawk.Emulation.CPUs.M6502
 					S = byte.Parse(args[1], NumberStyles.HexNumber);
 				else if (args[0] == "NMI")
 					NMI = bool.Parse(args[1]);
-				else if (args[0] == "Interrupt")
+				else if (args[0] == "IRQ")
-					Interrupt = bool.Parse(args[1]);
+					IRQ = bool.Parse(args[1]);
 				else if (args[0] == "TotalExecutedCycles")
 					TotalExecutedCycles = int.Parse(args[1]);
 				else if (args[0] == "PendingCycles")

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

@@ -47,13 +47,16 @@ namespace BizHawk.Emulation.Consoles.Nintendo
 				//reg0
 				int duty_cnt, env_loop, env_constant, env_cnt_value;
 				//reg1
-				int sweep_en, sweep_period, negate, shiftcount;
+				int sweep_en, sweep_divider_cnt, sweep_negate, sweep_shiftcount;
+				bool sweep_reload;
 				//reg2/3
 				int len_cnt;
 				int timer_raw_reload_value, timer_reload_value;
 
-				//from other apu regs
+				//misc..
-				public int lenctr_en;
+				int lenctr_en;
+
+				public bool IsLenCntNonZero() { return len_cnt > 0; }
 
 				public void WriteReg(int addr, byte val)
 				{
@@ -67,30 +70,42 @@ namespace BizHawk.Emulation.Consoles.Nintendo
 							duty_cnt = (val >> 6) & 3;
 							break;
 						case 1:
-							shiftcount = val & 7;
+							sweep_shiftcount = val & 7;
-							negate = (val >> 3) & 1;
+							sweep_negate = (val >> 3) & 1;
-							sweep_period = (val >> 4) & 7;
+							sweep_divider_cnt = (val >> 4) & 7;
 							sweep_en = (val >> 7) & 1;
+							sweep_reload = true;
 							break;
 						case 2:
 							timer_reload_value = (timer_reload_value & ~0xFF) | val;
-							calc_sweep_unit();
+							timer_raw_reload_value = timer_reload_value * 2 + 2;
+							//if (unit == 1) Console.WriteLine("{0} timer_reload_value: {1}", unit, timer_reload_value);
 							break;
 						case 3:
 							len_cnt = LENGTH_TABLE[(val >> 3) & 0x1F];
 							timer_reload_value = (timer_reload_value & 0xFF) | ((val & 0x07) << 8);
-							timer_raw_reload_value = timer_reload_value * 2;
+							timer_raw_reload_value = timer_reload_value * 2 + 2;
-							duty_step = 0;
+							//duty_step = 0; //?just a guess?
 							timer_counter = timer_raw_reload_value;
-							calc_sweep_unit();
 							env_start_flag = 1;
+
+							//allow the lenctr_en to kill the len_cnt
+							set_lenctr_en(lenctr_en);
+							
 							//serves as a useful note-on diagnostic
-							//Console.WriteLine("{0} timer_reload_value: {1}", unit, timer_reload_value);
+							//if(unit==1) Console.WriteLine("{0} timer_reload_value: {1}", unit, timer_reload_value);
 							break;
 					}
 				}
 
-				int swp_val_result;
+				public void set_lenctr_en(int value)
+				{
+					lenctr_en = value;
+					//if the length counter is not enabled, then we must disable the length system in this way
+					if (lenctr_en == 0) len_cnt = 0;
+				}
+
+				int swp_divider_counter;
 				bool swp_silence;
 				int duty_step;
 				int timer_counter;
@@ -98,27 +113,51 @@ namespace BizHawk.Emulation.Consoles.Nintendo
 
 				int env_start_flag, env_divider, env_counter, env_output;
 
-				void calc_sweep_unit()
-				{
-					//1's complement for chan 0, 2's complement if chan 1
-					if (negate == 1) //check to see if negate is on
-						swp_val_result = ~swp_val_result + unit;
-					//add with the shifter chan
-					swp_val_result += timer_reload_value;
-
-					if ((timer_reload_value < 8) ||
-						 ((swp_val_result > 0x7FF) && (negate==0)))
-						swp_silence = true; //silence
-					else
-						swp_silence = false; //don't silence
-
-				}
-
 				public void clock_length_and_sweep()
 				{
-					//(as well as length counter)
+					//this should be optimized to update only when `timer_reload_value` changes
-					if(sweep_en==1)
+					int sweep_shifter = timer_reload_value >> sweep_shiftcount;
-						timer_raw_reload_value = swp_val_result & 0x7FF;
+					if (sweep_negate == 1)
+						sweep_shifter = ~sweep_shifter + unit;
+					sweep_shifter += timer_reload_value;
+
+					//this sweep logic is always enabled:
+					swp_silence = (timer_reload_value < 8 || (sweep_shifter > 0x7FF && sweep_negate == 0));
+
+					//does enable only block the pitch bend? does the clocking proceed?
+					if (sweep_en == 1)
+					{
+						//clock divider
+						if (swp_divider_counter != 0) swp_divider_counter--;
+						if (swp_divider_counter == 0)
+						{
+							swp_divider_counter = sweep_divider_cnt + 1;
+						
+							//divider was clocked: process sweep pitch bend
+							if (sweep_shiftcount != 0 && !swp_silence)
+							{
+								timer_reload_value = sweep_shifter;
+								timer_raw_reload_value = timer_reload_value * 2 + 2;
+							}
+							//TODO - does this change the user's reload value or the latched reload value?
+						}
+
+						//handle divider reload, after clocking happens
+						if (sweep_reload)
+						{
+							swp_divider_counter = sweep_divider_cnt + 1;
+							sweep_reload = false;
+						}
+
+
+					}
+
+
+
+					
+					//env_loopdoubles as "halt length counter"
+					if (env_loop == 0 && len_cnt > 0)
+						len_cnt--;
 				}
 
 				public void clock_env()
@@ -131,7 +170,7 @@ namespace BizHawk.Emulation.Consoles.Nintendo
 					}
 					else
 					{
-						env_divider--;
+						if(env_divider != 0) env_divider--;
 						if (env_divider == 0)
 						{
 							env_divider = (env_cnt_value + 1);
@@ -162,7 +201,7 @@ namespace BizHawk.Emulation.Consoles.Nintendo
 					{
 						duty_step = (duty_step + 1) & 7;
 						//reload timer
-						timer_counter = timer_raw_reload_value + 2;
+						timer_counter = timer_raw_reload_value;
 					}
 					if (PULSE_DUTY[duty_cnt, duty_step] == 1) //we are outputting something
 					{
@@ -171,8 +210,8 @@ namespace BizHawk.Emulation.Consoles.Nintendo
 						if (swp_silence)
 							sample = 0;
 
-						//if (len_cnt==0) //length counter is 0
+						if (len_cnt==0) //length counter is 0
-						//    sample = 0; //silenced
+						    sample = 0; //silenced
 					}
 					else
 						sample = 0; //duty cycle is 0, silenced.
@@ -269,7 +308,7 @@ namespace BizHawk.Emulation.Consoles.Nintendo
 			PulseUnit[] pulse = { new PulseUnit(0), new PulseUnit(1) };
 			TriangleUnit triangle = new TriangleUnit();
 
-			int sequencer_counter, sequencer_step, sequencer_mode, sequencer_irq_inhibit, sequencer_irq_flag;
+			int sequencer_counter, sequencer_step, sequencer_mode, sequencer_irq_inhibit;
 			void sequencer_reset()
 			{
 				sequencer_counter = 0;
@@ -308,9 +347,7 @@ namespace BizHawk.Emulation.Consoles.Nintendo
 						{
 							if (sequencer_irq_inhibit == 0)
 							{
-								sequencer_irq_flag = 1;
+								nes.irq_apu = true;
-								//nes.cpu.Interrupt = true;
-								//Console.WriteLine("APU trigger IRQ (cpu needs implementation)");
 							}
 							sequencer_step = 0;
 						}
@@ -349,13 +386,14 @@ namespace BizHawk.Emulation.Consoles.Nintendo
 						triangle.WriteReg(addr - 0x4008, val);
 						break;
 					case 0x4015:
-						pulse[0].lenctr_en = (val & 1);
+						pulse[0].set_lenctr_en(val & 1);
-						pulse[1].lenctr_en = ((val>>1) & 1);
+						pulse[1].set_lenctr_en((val >> 1) & 1);
 						break;
 					case 0x4017:
 						sequencer_mode = (val>>7)&1;
-						if(((val>>6)&1)==1)
+						sequencer_irq_inhibit = (val >> 6) & 1;
-							sequencer_irq_inhibit = 0;
+						if (sequencer_irq_inhibit == 1)
+							nes.irq_apu = false;
 						sequencer_reset();
 						break;
 				}
@@ -365,8 +403,22 @@ namespace BizHawk.Emulation.Consoles.Nintendo
 			{
 				switch (addr)
 				{
+					case 0x4015:
+					{
+						//notice a missing bit here. should properly emulate with empty bus
+						//if an interrupt flag was set at the same moment of the read, it will read back as 1 but it will not be cleared. 
+						int dmc_irq_flag = 0; //todo
+						int dmc_nonzero = 0; //todo
+						int noise_nonzero = 0; //todo
+						int tri_nonzero = 0; //todo
+						int pulse1_nonzero = pulse[1].IsLenCntNonZero() ? 1 : 0;
+						int pulse0_nonzero = pulse[0].IsLenCntNonZero() ? 1 : 0;
+						int ret = (dmc_irq_flag << 7) | ((nes.irq_apu?1:0) << 6) | (dmc_nonzero << 4) | (noise_nonzero << 3) | (tri_nonzero<<2) | (pulse1_nonzero<<1) | (pulse0_nonzero);
+						nes.irq_apu = false;
+						return (byte)ret;
+					}
 					default:
-						return 0x00;
+						return 0xFF;
 				}
 			}
 
@@ -376,6 +428,11 @@ namespace BizHawk.Emulation.Consoles.Nintendo
 					RunOne();
 			}
 
+			public void DiscardSamples()
+			{
+				metaspu.buffer.clear();
+			}
+
 			void RunOne()
 			{
 				pulse[0].Run();

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

@@ -23,6 +23,13 @@ namespace BizHawk.Emulation.Consoles.Nintendo
 		CartInfo cart; //the current cart prototype. should be moved into the board, perhaps
 		INESBoard board; //the board hardware that is currently driving things
 
+		bool _irq_apu;
+		public bool irq_apu { get { return _irq_apu; } set { _irq_apu = value; sync_irq(); } }
+		void sync_irq()
+		{
+			cpu.IRQ = _irq_apu;
+		}
+
 		//user configuration 
 		int[,] palette = new int[64,3];
 		int[] palette_compiled = new int[64];

BizHawk.Emulation/Interfaces/Base Implementations/NullEmulator.cs

@@ -46,6 +46,7 @@ namespace BizHawk
         public int BufferHeight { get { return 192; } }
         public int BackgroundColor { get { return 0; } }
         public void GetSamples(short[] samples) { }
+		public void DiscardSamples() { }
         private IList<MemoryDomain> memoryDomains;
         public IList<MemoryDomain> MemoryDomains { get { return memoryDomains; } }
         public MemoryDomain MainMemory { get { return memoryDomains[0]; } }

BizHawk.Emulation/Interfaces/ISoundProvider.cs

@@ -3,5 +3,6 @@
     public interface ISoundProvider
     {
         void GetSamples(short[] samples);
+		void DiscardSamples();
     }
 }

BizHawk.Emulation/Sound/HuC6280PSG.cs

@@ -127,6 +127,7 @@ namespace BizHawk.Emulation.Sound
             }
         }
 
+		public void DiscardSamples() { /*TBD*/ }
         public void GetSamples(short[] samples)
         {
             int elapsedCycles = frameStopTime - frameStartTime;

BizHawk.Emulation/Sound/SN76489.cs

@@ -416,6 +416,7 @@ namespace BizHawk.Emulation.Sound
 
         #endregion
 
+		public void DiscardSamples() { /* todo */ }
         public void GetSamples(short[] samples)
         {
             int elapsedCycles = frameStopTime - frameStartTime;

BizHawk.Emulation/Sound/Utilities/BufferedAsync.cs

@@ -23,6 +23,12 @@ namespace BizHawk.Emulation.Sound
         private const int TargetExtraSamples = 882;
         private const int MaxExcessSamples = 4096;
 
+		public void DiscardSamples()
+		{
+			if(BaseSoundProvider != null)
+				BaseSoundProvider.DiscardSamples();
+		}
+
         public void GetSamples(short[] samples)
         {
             int samplesToGenerate = SamplesInOneFrame;

BizHawk.Emulation/Sound/Utilities/Metaspu.cs

@@ -19,12 +19,17 @@ namespace BizHawk.Emulation.Sound
 		{
 			buffer.output_samples(samples, samples.Length / 2);
 		}
+		public void DiscardSamples()
+		{
+			buffer.clear();
+		}
 	}
 
 	public interface ISynchronizingAudioBuffer
 	{
 		void enqueue_samples(short[] buf, int samples_provided);
 		void enqueue_sample(short left, short right);
+		void clear();
 		
 		//returns the number of samples actually supplied, which may not match the number requested
 		int output_samples(short[] buf, int samples_requested);
@@ -69,6 +74,11 @@ namespace BizHawk.Emulation.Sound
 		//adjustobuf(200,1000)
 		bool mixqueue_go = false;
 
+		public void clear()
+		{
+			adjustobuf.clear();
+		}
+
 		public void enqueue_sample(short left, short right)
 		{
 			adjustobuf.enqueue(left, right);
@@ -122,12 +132,7 @@ namespace BizHawk.Emulation.Sound
 			{
 				minLatency = _minLatency;
 				maxLatency = _maxLatency;
-				rollingTotalSize = 0;
+				clear();
-				targetLatency = (maxLatency + minLatency)/2;
-				rate = 1.0f;
-				cursor = 0.0f;
-				curr[0] = curr[1] = 0;
-				kAverageSize = 80000;
 			}
 
 			float rate, cursor;
@@ -137,6 +142,19 @@ namespace BizHawk.Emulation.Sound
 			public int size = 0;
 			short[] curr = new short[2];
 
+			public void clear()
+			{
+				buffer.Clear();
+				statsHistory.Clear();
+				rollingTotalSize = 0;
+				targetLatency = (maxLatency + minLatency) / 2;
+				rate = 1.0f;
+				cursor = 0.0f;
+				curr[0] = curr[1] = 0;
+				kAverageSize = 80000;
+				size = 0;
+			}
+
 			public void enqueue(short left, short  right) 
 			{
 				buffer.Enqueue(left);
@@ -244,6 +262,11 @@ namespace BizHawk.Emulation.Sound
 			return new ssamp((short)lrv,(short)rrv);
 		}
 
+		public void clear()
+		{
+			sampleQueue.Clear();
+		}
+
 		static void emit_sample(short[] outbuf, ref int cursor, ssamp sample)
 		{
 			outbuf[cursor++] = sample.l;

BizHawk.Emulation/Sound/Utilities/SoundMixer.cs

@@ -24,6 +24,12 @@ namespace BizHawk.Emulation.Sound
             SoundProviders.Remove(source);
         }
 
+		public void DiscardSamples()
+		{
+			foreach (var soundSource in SoundProviders)
+				soundSource.DiscardSamples();
+		}
+
         public void GetSamples(short[] samples)
         {
             foreach (var soundSource in SoundProviders)

BizHawk.Emulation/Sound/YM2413.cs

@@ -38,6 +38,7 @@ namespace BizHawk.Emulation.Sound
 			OPLL_writeReg(opll, register, value);
 		}
 
+		public void DiscardSamples() { }
         public void GetSamples(short[] samples)
         {
             for (int i=0; i<samples.Length;)

BizHawk.Emulation/Sound/YM2612.cs

@@ -17,6 +17,7 @@
         {
         }
 
+		public void DiscardSamples() { }
         public void GetSamples(short[] samples)
         {
             // TODO

BizHawk.MultiClient/MainForm.cs

@@ -125,12 +125,19 @@ namespace BizHawk.MultiClient
 					cmdRom = arg;
 			}
 
-			if (cmdRom != null) //Commandline should always override auto-load
+			if (cmdRom != null)
+			{
+				//Commandline should always override auto-load
 				LoadRom(cmdRom);
+				if (Global.Game == null)
+				{
+					MessageBox.Show("Failed to load rom specified on commandline");
+				}
+			}
 			else if (Global.Config.AutoLoadMostRecentRom && !Global.Config.RecentRoms.IsEmpty())
 				LoadRomFromRecent(Global.Config.RecentRoms.GetRecentFileByPosition(0));
 
-			if (cmdLoadState != null)
+			if (cmdLoadState != null && Global.Game != null)
 				LoadState("QuickSave" + cmdLoadState);
 
 			if (Global.Config.AutoLoadRamWatch)

BizHawk.MultiClient/Sound.cs

@@ -14,6 +14,7 @@ namespace BizHawk.MultiClient
         private byte[] SoundBuffer;
         private const int BufferSize = 4410 * 2 * 2; // 1/10th of a second, 2 bytes per sample, 2 channels;
         //private int SoundBufferPosition; //TODO: use this
+		bool needDiscard;
 
         private BufferedAsync semisync = new BufferedAsync();
         
@@ -48,6 +49,8 @@ namespace BizHawk.MultiClient
 			if(IsPlaying)
 				return;
 
+			needDiscard = true;
+
             DSoundBuffer.Write(SoundBuffer, 0, LockFlags.EntireBuffer);
 
             DSoundBuffer.CurrentPlayPosition = 0;
@@ -112,7 +115,10 @@ namespace BizHawk.MultiClient
         public void UpdateSound(ISoundProvider soundProvider)
         {
 			if (Global.Config.SoundEnabled == false || disposed)
-                return;
+			{
+				soundProvider.DiscardSamples();
+				return;
+			}
 
 			int samplesNeeded = SNDDXGetAudioSpace()*2;
 			if (samplesNeeded == 0)
@@ -121,11 +127,12 @@ namespace BizHawk.MultiClient
             short[] samples = new short[samplesNeeded];
 			//Console.WriteLine(samplesNeeded/2);
 
-            if (soundProvider != null && Muted == false)
+			if (soundProvider != null && Muted == false)
-            {
+			{
-                semisync.BaseSoundProvider = soundProvider;
+				semisync.BaseSoundProvider = soundProvider;
-                semisync.GetSamples(samples);
+				semisync.GetSamples(samples);
-            }
+			}
+			else soundProvider.DiscardSamples();
 
 			int cursor = soundoffset;
 			for (int i = 0; i < samples.Length; i++)

CpuCoreGenerator/MOS 6502/CoreGenerator.cs

@@ -364,6 +364,10 @@ namespace M6502
             w.WriteLine("                   TriggerException(ExceptionType.NMI);");
             w.WriteLine("                   NMI = false;");
             w.WriteLine("               }");
+			w.WriteLine("               if (IRQ && !FlagI)");
+			w.WriteLine("               {");
+			w.WriteLine("                   TriggerException(ExceptionType.IRQ);");
+			w.WriteLine("               }");
             w.WriteLine("");
 
             w.WriteLine("                if(debug) Console.WriteLine(State());");