From 7aff56bef59f08879cdbd31cf70adea826c98ebb Mon Sep 17 00:00:00 2001
From: Scott Mansell <phiren@gmail.com>
Date: Thu, 17 Jul 2014 23:56:23 +1200
Subject: [PATCH] Implement the correct method for determining field order.

Based on advice from tueidj we implement this method based on how
TVs actually determin the field order.

Removes spammy messages about "Invalid field order"
---
 Source/Core/Core/HW/VideoInterface.cpp | 37 +++++++++++++-------------
 1 file changed, 18 insertions(+), 19 deletions(-)

diff --git a/Source/Core/Core/HW/VideoInterface.cpp b/Source/Core/Core/HW/VideoInterface.cpp
index ee83dcbd29..8c88d3cb10 100644
--- a/Source/Core/Core/HW/VideoInterface.cpp
+++ b/Source/Core/Core/HW/VideoInterface.cpp
@@ -519,28 +519,27 @@ static void BeginField(FieldType field)
 	u32 fbHeight = m_VerticalTimingRegister.ACV * (field == FIELD_PROGRESSIVE ? 1 : 2);
 	u32 xfbAddr;
 
-	// NTSC and PAL have opposite field orders.
-	if (m_DisplayControlRegister.FMT == 1) // PAL
+	// Only the top field is valid in progressive mode.
+	if (field == FieldType::FIELD_PROGRESSIVE)
 	{
-		// But the PAL ports of some games are poorly programmed and don't use correct ordering.
-		// Zelda: Wind Waker and Simpsons Hit & Run are exampes of this, there are probally more.
-		// PAL Wind Waker also runs at 30fps instead of 25.
-		if (field == FieldType::FIELD_PROGRESSIVE || GetXFBAddressBottom() != (GetXFBAddressTop() - 1280))
-		{
-			WARN_LOG(VIDEOINTERFACE, "PAL game is trying to use incorrect (NTSC) field ordering");
-			// Lets kindly fix this for them.
-			xfbAddr = GetXFBAddressTop();
-
-			// TODO: PAL Simpsons Hit & Run now has a green line at the bottom when Real XFB is used.
-			// Might be a bug later on in our code, or a bug in the actual game.
-		}
-		else
-		{
-			xfbAddr = GetXFBAddressBottom();
-		}
-	} else {
 		xfbAddr = GetXFBAddressTop();
 	}
+	else
+	{
+		// If we are displaying an interlaced field, we convert it to a progressive field
+		// by simply using the whole XFB, which 99% of the time contains a whole progressive
+		// frame.
+
+		// All known NTSC games use the top/odd field as the upper field but
+		// PAL games are known to whimsically arrange the fields in either order.
+		// So to work out which field is pointing to the top of the progressive XFB we check
+		// which field has the lower PRB value in the VBlank Timing Registers.
+
+		if(m_VBlankTimingOdd.PRB < m_VBlankTimingEven.PRB)
+			xfbAddr = GetXFBAddressTop();
+		else
+			xfbAddr = GetXFBAddressBottom();
+	}
 
 	static const char* const fieldTypeNames[] = { "Progressive", "Upper", "Lower" };