PPU: Tweak affected bits for $2006 scroll glitch based on Alien Syndr…

…ome (J) behavior (and other hardware tests) It looks like the horizontal nametable bit is also affected when the write falls on a coarse scroll increment
SourMesen · Apr 24, 2020 · e586ce7 · e586ce7 · ImSpecial · Apr 24, 2020
1 parent 5d67994
commit e586ce7
Showing 1 changed file with 1 addition and 1 deletion.
diff --git a/Core/PPU.cpp b/Core/PPU.cpp
@@ -1330,7 +1330,7 @@ void PPU::UpdateState()
 						debugger->BreakImmediately(BreakSource::BreakOnPpu2006ScrollGlitch);
 					}
 				} else if(_cycle > 0 && (_cycle & 0x07) == 0 && (_cycle <= 256 || _cycle > 320)) {
-					_state.VideoRamAddr = (_updateVramAddr & ~0x1F) | (_state.VideoRamAddr & _updateVramAddr & 0x1F);
+					_state.VideoRamAddr = (_updateVramAddr & ~0x41F) | (_state.VideoRamAddr & _updateVramAddr & 0x41F);
 					shared_ptr<Debugger> debugger = _console->GetDebugger(false);
 					if(debugger && debugger->CheckFlag(DebuggerFlags::BreakOnPpu2006ScrollGlitch)) {
 						debugger->BreakImmediately(BreakSource::BreakOnPpu2006ScrollGlitch);