Fix VRAM end of line testROM and a desync in GB Wario Land II

libgambatte/src/memory.cpp

@@ -655,6 +655,11 @@ unsigned Memory::nontrivial_read(unsigned const p, unsigned long const cc) {
 				if (!lcd_.vramReadable(cc))
 					return 0xFF;
 
+				if (lcd_.vramExactlyReadable(cc))
+					if (p < 0x9000) {
+						return 0x00;
+					}
+
 				return cart_.vrambankptr()[p];
 			}
 

libgambatte/src/video.cpp

@@ -290,6 +290,15 @@ bool LCD::vramReadable(unsigned long const cc) {
 		|| cc + 2 >= m0TimeOfCurrentLine(cc);
 }
 
+bool LCD::vramExactlyReadable(unsigned long const cc) {
+	bool currentVramExactlyReadable = (cc + 2 == m0TimeOfCurrentLine(cc));
+	bool vramAlreadyExactlyRead = vramHasBeenExactlyRead;
+	if (currentVramExactlyReadable) {
+		vramHasBeenExactlyRead = true;
+	}
+	return !vramAlreadyExactlyRead && currentVramExactlyReadable;
+}
+
 bool LCD::vramWritable(unsigned long const cc) {
 	if (cc >= eventTimes_.nextEventTime())
 		update(cc);
@@ -848,4 +857,5 @@ SYNCFUNC(LCD)
 	SSS(lycIrq_);
 	SSS(nextM0Time_);
 	NSS(statReg_);
+	NSS(vramHasBeenExactlyRead);
 }

libgambatte/src/video.h

@@ -102,6 +102,7 @@ public:
 	void resetCc(unsigned long oldCC, unsigned long newCc);
 	void speedChange(unsigned long cycleCounter);
 	bool vramReadable(unsigned long cycleCounter);
+	bool vramExactlyReadable(unsigned long cycleCounter);
 	bool vramWritable(unsigned long cycleCounter);
 	bool oamReadable(unsigned long cycleCounter);
 	bool oamWritable(unsigned long cycleCounter);
@@ -228,6 +229,7 @@ public:
 	LycIrq lycIrq_;
 	NextM0Time nextM0Time_;
 	unsigned char statReg_;
+	bool vramHasBeenExactlyRead = false;
 
 	static void setDmgPalette(unsigned long palette[],
 	                          unsigned long const dmgColors[],
@@ -235,13 +237,13 @@ public:
 
 	unsigned long gbcToRgb32(const unsigned bgr15);
 	void doCgbColorChange(unsigned char *const pdata, unsigned long *const palette, unsigned index, const unsigned data);
-
 	void refreshPalettes();
 	void setDBuffer();
 	void doMode2IrqEvent();
 	void event();
 	unsigned long m0TimeOfCurrentLine(unsigned long cc);
 	bool cgbpAccessible(unsigned long cycleCounter);
+	
 	bool lycRegChangeStatTriggerBlockedByM0OrM1Irq(unsigned data, unsigned long cc);
 	bool lycRegChangeTriggersStatIrq(unsigned old, unsigned data, unsigned long cc);
 	bool statChangeTriggersM0LycOrM1StatIrqCgb(unsigned old, unsigned data, bool lycperiod, unsigned long cc);