From 82ad2194616e51f383fef2aacda3d29c38af1a3f Mon Sep 17 00:00:00 2001
From: zeromus <zeromus@zeromus.org>
Date: Sun, 20 Mar 2011 20:42:12 +0000
Subject: [PATCH] [NES] some little speedups, just to prove that it can be done

---
 .../Consoles/Nintendo/NES/APU.cs              | 13 +++++-----
 .../Consoles/Nintendo/NES/BoardSystem.cs      |  1 -
 .../Consoles/Nintendo/NES/Core.cs             | 24 +++++++++----------
 .../Consoles/Nintendo/NES/NES.cs              | 10 +++++---
 .../Consoles/Nintendo/NES/PPU.run.cs          |  4 ++--
 5 files changed, 28 insertions(+), 24 deletions(-)

diff --git a/BizHawk.Emulation/Consoles/Nintendo/NES/APU.cs b/BizHawk.Emulation/Consoles/Nintendo/NES/APU.cs
index 64e37dd18c..08296f77cb 100644
--- a/BizHawk.Emulation/Consoles/Nintendo/NES/APU.cs
+++ b/BizHawk.Emulation/Consoles/Nintendo/NES/APU.cs
@@ -233,6 +233,7 @@ namespace BizHawk.Emulation.Consoles.Nintendo
 				int timer_counter;
 				public int sample;
 				int env_output, env_start_flag, env_divider, env_counter;
+				bool noise_bit = true;
 
 				public bool IsLenCntNonZero() { return len_cnt > 0; }
 
@@ -304,7 +305,7 @@ namespace BizHawk.Emulation.Consoles.Nintendo
 				public void Run()
 				{
 					if (timer_counter > 0) timer_counter--;
-					if (timer_counter == 0)
+					if (timer_counter == 0 && period_cnt != 0)
 					{
 						//reload timer
 						timer_counter = period_cnt;
@@ -315,12 +316,12 @@ namespace BizHawk.Emulation.Consoles.Nintendo
 						shift_register >>= 1;
 						shift_register &= ~(1 << 14);
 						shift_register |= (feedback << 14);
+						noise_bit = (shift_register & 1)!=0;
 					}
 
-					sample = env_output;
-					if ((shift_register & 1) == 0) sample = 0;
-					if (len_cnt == 0) 
-						sample = 0;
+					if (noise_bit || len_cnt==0) sample = 0;
+					else
+						sample = env_output;
 				}
 			}
 
@@ -546,7 +547,7 @@ namespace BizHawk.Emulation.Consoles.Nintendo
 				metaspu.buffer.clear();
 			}
 
-			void RunOne()
+			public void RunOne()
 			{
 				pulse[0].Run();
 				pulse[1].Run();
diff --git a/BizHawk.Emulation/Consoles/Nintendo/NES/BoardSystem.cs b/BizHawk.Emulation/Consoles/Nintendo/NES/BoardSystem.cs
index 8b446f949c..84a01efa16 100644
--- a/BizHawk.Emulation/Consoles/Nintendo/NES/BoardSystem.cs
+++ b/BizHawk.Emulation/Consoles/Nintendo/NES/BoardSystem.cs
@@ -250,7 +250,6 @@ namespace BizHawk.Emulation.Consoles.Nintendo
 			if (choices.Count == 0) return null;
 
 			//pick the first board for this hash arbitrarily. it probably doesn't make a difference
-			Console.WriteLine("Chose board from nescartdb:");
 			return choices[0];
 		}
 
diff --git a/BizHawk.Emulation/Consoles/Nintendo/NES/Core.cs b/BizHawk.Emulation/Consoles/Nintendo/NES/Core.cs
index 34b1996d9c..5a99243c60 100644
--- a/BizHawk.Emulation/Consoles/Nintendo/NES/Core.cs
+++ b/BizHawk.Emulation/Consoles/Nintendo/NES/Core.cs
@@ -65,6 +65,13 @@ namespace BizHawk.Emulation.Consoles.Nintendo
 		bool resetSignal;
 		public void FrameAdvance(bool render)
 		{
+			if (resetSignal)
+			{
+				cpu.PC = cpu.ReadWord(MOS6502.ResetVector);
+				apu.WriteReg(0x4015, 0);
+				cpu.FlagI = true;
+			}
+
 			Controller.UpdateControls(Frame++);
 			if (resetSignal)
 				Controller.UnpressButton("Reset");
@@ -74,24 +81,17 @@ namespace BizHawk.Emulation.Consoles.Nintendo
 
 		protected void RunCpu(int ppu_cycles)
 		{
-			if (resetSignal)
-			{
-				cpu.PC = cpu.ReadWord(MOS6502.ResetVector);
-				apu.WriteReg(0x4015, 0);
-				cpu.FlagI = true;
-			}
-
 			int cycles = ppu_cycles;
 			if (ppu.PAL)
-				cycles *= 15;
+			    cycles *= 15;
 			else
-				cycles *= 16;
+				cycles <<= 4;
 
 			cpu_accumulate += cycles;
-			int todo = cpu_accumulate / 48;
-			cpu_accumulate -= todo * 48;
-			if (todo > 0)
+			if (cpu_accumulate >= 48)
 			{
+				int todo = cpu_accumulate / 48;
+				cpu_accumulate -= todo * 48;
 				cpu.Execute(todo);
 				apu.Run(todo);
 			}
diff --git a/BizHawk.Emulation/Consoles/Nintendo/NES/NES.cs b/BizHawk.Emulation/Consoles/Nintendo/NES/NES.cs
index 2675e07201..ab4fc9b887 100644
--- a/BizHawk.Emulation/Consoles/Nintendo/NES/NES.cs
+++ b/BizHawk.Emulation/Consoles/Nintendo/NES/NES.cs
@@ -412,7 +412,7 @@ namespace BizHawk.Emulation.Consoles.Nintendo
 				CartInfo choice = null;
 				if(USE_DATABASE)
 					choice = IdentifyFromBootGodDB(hash_sha1);
-				if(choice == null)
+				if (choice == null)
 				{
 					if (USE_DATABASE)
 					{
@@ -435,10 +435,14 @@ namespace BizHawk.Emulation.Consoles.Nintendo
 					else
 					{
 						origin = EDetectionOrigin.GameDB;
-						Console.WriteLine("Chose board from gamedb: ");
+						Console.WriteLine("Chose board from gamedb: " + board);
 					}
 				}
-				else origin = EDetectionOrigin.BootGodDB;
+				else
+				{
+					Console.WriteLine("Chose board from nescartdb: " + choice.board_type);
+					origin = EDetectionOrigin.BootGodDB;
+				}
 
 				Console.WriteLine(choice.game);
 				Console.WriteLine(choice);
diff --git a/BizHawk.Emulation/Consoles/Nintendo/NES/PPU.run.cs b/BizHawk.Emulation/Consoles/Nintendo/NES/PPU.run.cs
index 05d88226c0..e2b196083b 100644
--- a/BizHawk.Emulation/Consoles/Nintendo/NES/PPU.run.cs
+++ b/BizHawk.Emulation/Consoles/Nintendo/NES/PPU.run.cs
@@ -403,7 +403,7 @@ namespace BizHawk.Emulation.Consoles.Nintendo
 					//screen (or basically, the first nametable address that will be accessed when
 					//the PPU is fetching background data on the next scanline).
 					//(not implemented yet)
-					runppu(kFetchTime);
+					runppu(kFetchTime*2);
 					if (sl == 0)
 					{
 						if (idleSynch && reg_2001.PPUON && !PAL)
@@ -414,7 +414,7 @@ namespace BizHawk.Emulation.Consoles.Nintendo
 					}
 					else
 						ppur.status.end_cycle = 341;
-					runppu(kFetchTime);
+					//runppu(kFetchTime);
 
 					//After memory access 170, the PPU simply rests for 4 cycles (or the
 					//equivelant of half a memory access cycle) before repeating the whole