From 03f160a949f361e08c5e05b4e68da88658312ade Mon Sep 17 00:00:00 2001
From: Sour <mesenemu@gmail.com>
Date: Sat, 11 May 2019 09:26:56 -0400
Subject: [PATCH] UNROM512: Fixed mirroring logic to match changes on the wiki
 (fixes Black Box Challenge)

---
 Core/NESHeader.cpp | 11 +----------
 Core/UnRom512.h    | 11 +++++++----
 2 files changed, 8 insertions(+), 14 deletions(-)

diff --git a/Core/NESHeader.cpp b/Core/NESHeader.cpp
index 818f3fb7..3a12dd77 100644
--- a/Core/NESHeader.cpp
+++ b/Core/NESHeader.cpp
@@ -180,16 +180,7 @@ uint8_t NESHeader::GetSubMapper()
 MirroringType NESHeader::GetMirroringType()
 {
 	if(Byte6 & 0x08) {
-		if(GetRomHeaderVersion() == RomHeaderVersion::Nes2_0) {
-			if(Byte6 & 0x01) {
-				//Based on proposal by rainwarrior/Myask: http://wiki.nesdev.com/w/index.php/Talk:NES_2.0
-				return MirroringType::ScreenAOnly;
-			} else {
-				return MirroringType::FourScreens;
-			}
-		} else {
-			return MirroringType::FourScreens;
-		}
+		return MirroringType::FourScreens;
 	} else {
 		return Byte6 & 0x01 ? MirroringType::Vertical : MirroringType::Horizontal;
 	}
diff --git a/Core/UnRom512.h b/Core/UnRom512.h
index 85fc061c..c46ab57c 100644
--- a/Core/UnRom512.h
+++ b/Core/UnRom512.h
@@ -19,10 +19,13 @@ protected:
 	void InitMapper() override
 	{
 		SelectPRGPage(1, -1);
-		if(IsNes20()) {
-			_enableMirroringBit = GetMirroringType() == MirroringType::ScreenAOnly;			
-		} else {
-			_enableMirroringBit = GetMirroringType() == MirroringType::FourScreens;
+
+		_enableMirroringBit = false;
+		switch(_romInfo.NesHeader.Byte6 & 0x09) {
+			case 0: SetMirroringType(MirroringType::Vertical); break;
+			case 1: SetMirroringType(MirroringType::Horizontal); break;
+			case 8: SetMirroringType(MirroringType::ScreenAOnly); _enableMirroringBit = true; break;
+			case 9: SetMirroringType(MirroringType::FourScreens); break;
 		}
 
 		if(GetMirroringType() == MirroringType::FourScreens && _chrRam && _chrRamSize >= 0x8000) {