From 8027ab53d0cdd5b7de2214f990cf7c12e56d50fd Mon Sep 17 00:00:00 2001
From: Nolan Check <Nolan.Check@gmail.com>
Date: Mon, 27 Jul 2009 22:05:38 +0000
Subject: [PATCH] Don't use events for efb access. As I've learned, events
 cause kernel calls and it is sometimes more efficient to do spin-waits. See
 if this speeds up Wind Waker's pictobox quests.

git-svn-id: https://dolphin-emu.googlecode.com/svn/trunk@3893 8ced0084-cf51-0410-be5f-012b33b47a6e
---
 Source/Core/Common/Src/Atomic_Win32.h       |  2 +-
 Source/Plugins/Plugin_VideoOGL/Src/main.cpp | 40 +++++++++------------
 2 files changed, 17 insertions(+), 25 deletions(-)

diff --git a/Source/Core/Common/Src/Atomic_Win32.h b/Source/Core/Common/Src/Atomic_Win32.h
index cd8b22075d..59d7da5abe 100644
--- a/Source/Core/Common/Src/Atomic_Win32.h
+++ b/Source/Core/Common/Src/Atomic_Win32.h
@@ -55,7 +55,7 @@ inline u32 AtomicLoad(volatile u32& src) {
 }
 inline u32 AtomicLoadAcquire(volatile u32& src) {
 	MemoryBarrier();
-	return src;
+	return src; // 32-bit reads are always atomic.
 }
 
 inline void AtomicStore(volatile u32& dest, u32 value) {
diff --git a/Source/Plugins/Plugin_VideoOGL/Src/main.cpp b/Source/Plugins/Plugin_VideoOGL/Src/main.cpp
index 6d3f360dae..ebf3ed4f5f 100644
--- a/Source/Plugins/Plugin_VideoOGL/Src/main.cpp
+++ b/Source/Plugins/Plugin_VideoOGL/Src/main.cpp
@@ -104,11 +104,8 @@ int GLScissorX, GLScissorY, GLScissorW, GLScissorH;
 
 static bool s_PluginInitialized = false;
 
-static volatile u32 s_swapRequested = false;
-static Common::Event s_swapResponseEvent;
-
-static volatile u32 s_efbAccessRequested = false;
-static Common::Event s_efbResponseEvent;
+static u32 s_swapRequested = FALSE;
+static u32 s_efbAccessRequested = FALSE;
 
 void GetDllInfo (PLUGIN_INFO* _PluginInfo)
 {
@@ -385,11 +382,7 @@ void Video_Prepare(void)
     TextureConverter::Init();
 
 	s_swapRequested = FALSE;
-	s_swapResponseEvent.Init();
-	s_swapResponseEvent.Set();
-
 	s_efbAccessRequested = FALSE;
-	s_efbResponseEvent.Init();
 
 	s_PluginInitialized = true;
 	INFO_LOG(VIDEO, "Video plugin initialized.");
@@ -400,10 +393,7 @@ void Shutdown(void)
 	s_PluginInitialized = false;
 
 	s_efbAccessRequested = FALSE;
-	s_efbResponseEvent.Shutdown();
-
 	s_swapRequested = FALSE;
-	s_swapResponseEvent.Shutdown();
 
 	Fifo_Shutdown();
 	PostProcessing::Shutdown();
@@ -472,8 +462,7 @@ void VideoFifo_CheckSwapRequest()
 		// TODO: Find better name for this because I don't know if it means what it says.
 		g_VideoInitialize.pCopiedToXFB();
 
-		s_swapRequested = FALSE;
-		s_swapResponseEvent.Set();
+		Common::AtomicStoreRelease(s_swapRequested, FALSE);
 	}
 }
 
@@ -507,13 +496,14 @@ void Video_BeginField(u32 xfbAddr, FieldType field, u32 fbWidth, u32 fbHeight)
 {
 	if (s_PluginInitialized)
 	{
-		if (s_swapRequested)
+		// Make sure previous swap request has made it to the screen
+		if (g_VideoInitialize.bUseDualCore)
 		{
-			if (g_VideoInitialize.bUseDualCore)
-				s_swapResponseEvent.MsgWait();
-			else
-				VideoFifo_CheckSwapRequest();
+			while (Common::AtomicLoadAcquire(s_swapRequested))
+				Common::YieldCPU();
 		}
+		else
+			VideoFifo_CheckSwapRequest();
 
 		s_beginFieldArgs.xfbAddr = xfbAddr;
 		s_beginFieldArgs.field = field;
@@ -531,14 +521,14 @@ void Video_EndField()
 	}
 }
 
-static volatile struct
+static struct
 {
 	EFBAccessType type;
 	u32 x;
 	u32 y;
 } s_accessEFBArgs;
 
-static volatile u32 s_AccessEFBResult = 0;
+static u32 s_AccessEFBResult = 0;
 
 void VideoFifo_CheckEFBAccess()
 {
@@ -546,8 +536,7 @@ void VideoFifo_CheckEFBAccess()
 	{
 		s_AccessEFBResult = Renderer::AccessEFB(s_accessEFBArgs.type, s_accessEFBArgs.x, s_accessEFBArgs.y);
 
-		s_efbAccessRequested = FALSE;
-		s_efbResponseEvent.Set();
+		Common::AtomicStoreRelease(s_efbAccessRequested, FALSE);
 	}
 }
 
@@ -562,7 +551,10 @@ u32 Video_AccessEFB(EFBAccessType type, u32 x, u32 y)
 		Common::AtomicStoreRelease(s_efbAccessRequested, TRUE);
 
 		if (g_VideoInitialize.bUseDualCore)
-			s_efbResponseEvent.MsgWait();
+		{
+			while (Common::AtomicLoadAcquire(s_efbAccessRequested))
+				Common::YieldCPU();
+		}
 		else
 			VideoFifo_CheckEFBAccess();