M CHANGES → CHANGES

@@ -57,6 +57,7 @@ - GBA Hardware: Fix crash if a savestate lies about game hardware
  - Test: Fix crash when fuzzing fails to load a file
  - Qt: Disable "New multiplayer window" when MAX_GBAS is reached (fixes mgba.io/i/107)
  - LR35902: Fix decoding LD r, $imm and 0-valued immediates (fixes mgba.io/i/735)
+ - GB: Fix STAT blocking
 Misc:
  - SDL: Remove scancode key input
  - GBA Video: Clean up unused timers

M src/gb/video.c → src/gb/video.c

@@ -106,6 +106,33 @@ renderer->vram = video->vram;
 	video->renderer->init(video->renderer, video->p->model);
 }
 
+static bool _statIRQAsserted(struct GBVideo* video, GBRegisterSTAT stat) {
+	// TODO: variable for the IRQ line value?
+	if (GBRegisterSTATIsLYCIRQ(stat) && GBRegisterSTATIsLYC(stat)) {
+		return true;
+	}
+	switch (GBRegisterSTATGetMode(stat)) {
+	case 0:
+		if (GBRegisterSTATIsHblankIRQ(stat)) {
+			return true;
+		}
+		break;
+	case 1:
+		if (GBRegisterSTATIsVblankIRQ(stat)) {
+			return true;
+		}
+		break;
+	case 2:
+		if (GBRegisterSTATIsOAMIRQ(stat)) {
+			return true;
+		}
+		break;
+	case 3:
+		break;
+	}
+	return false;
+}
+
 void _endMode0(struct mTiming* timing, void* context, uint32_t cyclesLate) {
 	struct GBVideo* video = context;
 	if (video->frameskipCounter <= 0) {
@@ -115,15 +142,13 @@ int lyc = video->p->memory.io[REG_LYC];
 	int32_t next;
 	++video->ly;
 	video->p->memory.io[REG_LY] = video->ly;
+	GBRegisterSTAT oldStat = video->stat;
 	video->stat = GBRegisterSTATSetLYC(video->stat, lyc == video->ly);
 	if (video->ly < GB_VIDEO_VERTICAL_PIXELS) {
 		// TODO: Cache SCX & 7 in case it changes during mode 2
 		next = GB_VIDEO_MODE_2_LENGTH + (video->p->memory.io[REG_SCX] & 7);
 		video->mode = 2;
 		video->modeEvent.callback = _endMode2;
-		if (!GBRegisterSTATIsHblankIRQ(video->stat) && GBRegisterSTATIsOAMIRQ(video->stat)) {
-			video->p->memory.io[REG_IF] |= (1 << GB_IRQ_LCDSTAT);
-		}
 	} else {
 		next = GB_VIDEO_HORIZONTAL_LENGTH;
 		video->mode = 1;
@@ -131,16 +156,16 @@ video->modeEvent.callback = _endMode1;
 
 		mTimingSchedule(&video->p->timing, &video->frameEvent, -cyclesLate);
 
-		if (GBRegisterSTATIsVblankIRQ(video->stat) || GBRegisterSTATIsOAMIRQ(video->stat)) {
+		if (!_statIRQAsserted(video, oldStat) && GBRegisterSTATIsOAMIRQ(video->stat)) {
 			video->p->memory.io[REG_IF] |= (1 << GB_IRQ_LCDSTAT);
 		}
 		video->p->memory.io[REG_IF] |= (1 << GB_IRQ_VBLANK);
 	}
-	if (!GBRegisterSTATIsHblankIRQ(video->stat) && GBRegisterSTATIsLYCIRQ(video->stat) && lyc == video->ly) {
+	video->stat = GBRegisterSTATSetMode(video->stat, video->mode);
+	if (!_statIRQAsserted(video, oldStat) && _statIRQAsserted(video, video->stat)) {
 		video->p->memory.io[REG_IF] |= (1 << GB_IRQ_LCDSTAT);
 	}
 	GBUpdateIRQs(video->p);
-	video->stat = GBRegisterSTATSetMode(video->stat, video->mode);
 	video->p->memory.io[REG_STAT] = video->stat;
 	mTimingSchedule(timing, &video->modeEvent, (next << video->p->doubleSpeed) - cyclesLate);
 }
@@ -160,10 +185,6 @@ video->p->memory.io[REG_LY] = video->ly;
 		next = GB_VIDEO_MODE_2_LENGTH + (video->p->memory.io[REG_SCX] & 7);
 		video->mode = 2;
 		video->modeEvent.callback = _endMode2;
-		if (GBRegisterSTATIsOAMIRQ(video->stat)) {
-			video->p->memory.io[REG_IF] |= (1 << GB_IRQ_LCDSTAT);
-			GBUpdateIRQs(video->p);
-		}
 		if (video->p->memory.mbcType == GB_MBC7 && video->p->memory.rotation && video->p->memory.rotation->sample) {
 			video->p->memory.rotation->sample(video->p->memory.rotation);
 		}
@@ -178,9 +199,10 @@ video->p->memory.io[REG_LY] = video->ly;
 		next = GB_VIDEO_HORIZONTAL_LENGTH;
 	}
 
+	GBRegisterSTAT oldStat = video->stat;
 	video->stat = GBRegisterSTATSetMode(video->stat, video->mode);
 	video->stat = GBRegisterSTATSetLYC(video->stat, lyc == video->p->memory.io[REG_LY]);
-	if (video->ly && GBRegisterSTATIsLYCIRQ(video->stat) && lyc == video->p->memory.io[REG_LY]) {
+	if (!_statIRQAsserted(video, oldStat) && _statIRQAsserted(video, video->stat)) {
 		video->p->memory.io[REG_IF] |= (1 << GB_IRQ_LCDSTAT);
 		GBUpdateIRQs(video->p);
 	}
@@ -196,7 +218,12 @@ video->dotClock = timing->masterCycles - cyclesLate;
 	int32_t next = GB_VIDEO_MODE_3_LENGTH_BASE + video->objMax * 11 - (video->p->memory.io[REG_SCX] & 7);
 	video->mode = 3;
 	video->modeEvent.callback = _endMode3;
+	GBRegisterSTAT oldStat = video->stat;
 	video->stat = GBRegisterSTATSetMode(video->stat, video->mode);
+	if (!_statIRQAsserted(video, oldStat) && _statIRQAsserted(video, video->stat)) {
+		video->p->memory.io[REG_IF] |= (1 << GB_IRQ_LCDSTAT);
+		GBUpdateIRQs(video->p);
+	}
 	video->p->memory.io[REG_STAT] = video->stat;
 	mTimingSchedule(timing, &video->modeEvent, (next << video->p->doubleSpeed) - cyclesLate);
 }
@@ -204,10 +231,6 @@
 void _endMode3(struct mTiming* timing, void* context, uint32_t cyclesLate) {
 	struct GBVideo* video = context;
 	GBVideoProcessDots(video);
-	if (GBRegisterSTATIsHblankIRQ(video->stat)) {
-		video->p->memory.io[REG_IF] |= (1 << GB_IRQ_LCDSTAT);
-		GBUpdateIRQs(video->p);
-	}
 	if (video->ly < GB_VIDEO_VERTICAL_PIXELS && video->p->memory.isHdma && video->p->memory.io[REG_HDMA5] != 0xFF) {
 		video->p->memory.hdmaRemaining = 0x10;
 		mTimingDeschedule(timing, &video->p->memory.hdmaEvent);
@@ -215,7 +238,12 @@ mTimingSchedule(timing, &video->p->memory.hdmaEvent, 0);
 	}
 	video->mode = 0;
 	video->modeEvent.callback = _endMode0;
+	GBRegisterSTAT oldStat = video->stat;
 	video->stat = GBRegisterSTATSetMode(video->stat, video->mode);
+	if (!_statIRQAsserted(video, oldStat) && _statIRQAsserted(video, video->stat)) {
+		video->p->memory.io[REG_IF] |= (1 << GB_IRQ_LCDSTAT);
+		GBUpdateIRQs(video->p);
+	}
 	video->p->memory.io[REG_STAT] = video->stat;
 	int32_t next = GB_VIDEO_MODE_0_LENGTH_BASE - video->objMax * 11;
 	mTimingSchedule(timing, &video->modeEvent, (next << video->p->doubleSpeed) - cyclesLate);
@@ -318,9 +346,10 @@
 		video->ly = 0;
 		video->p->memory.io[REG_LY] = 0;
 		// TODO: Does this read as 0 for 4 T-cycles?
+		GBRegisterSTAT oldStat = video->stat;
 		video->stat = GBRegisterSTATSetMode(video->stat, 2);
 		video->stat = GBRegisterSTATSetLYC(video->stat, video->ly == video->p->memory.io[REG_LYC]);
-		if (GBRegisterSTATIsLYCIRQ(video->stat) && video->ly == video->p->memory.io[REG_LYC]) {
+		if (!_statIRQAsserted(video, oldStat) && _statIRQAsserted(video, video->stat)) {
 			video->p->memory.io[REG_IF] |= (1 << GB_IRQ_LCDSTAT);
 			GBUpdateIRQs(video->p);
 		}
@@ -344,20 +373,21 @@ video->p->memory.io[REG_STAT] = video->stat;
 }
 
 void GBVideoWriteSTAT(struct GBVideo* video, GBRegisterSTAT value) {
+	GBRegisterSTAT oldStat = video->stat;
 	video->stat = (video->stat & 0x7) | (value & 0x78);
-	if (video->p->model == GB_MODEL_DMG && video->mode == 1) {
+	if (video->p->model == GB_MODEL_DMG && !_statIRQAsserted(video, oldStat) && video->mode < 3) {
+		// TODO: variable for the IRQ line value?
 		video->p->memory.io[REG_IF] |= (1 << GB_IRQ_LCDSTAT);
 		GBUpdateIRQs(video->p);
 	}
 }
 
 void GBVideoWriteLYC(struct GBVideo* video, uint8_t value) {
-	if (video->mode == 2) {
-		video->stat = GBRegisterSTATSetLYC(video->stat, value == video->ly);
-		if (GBRegisterSTATIsLYCIRQ(video->stat) && value == video->ly) {
-			video->p->memory.io[REG_IF] |= (1 << GB_IRQ_LCDSTAT);
-			GBUpdateIRQs(video->p);
-		}
+	GBRegisterSTAT oldStat = video->stat;
+	video->stat = GBRegisterSTATSetLYC(video->stat, value == video->ly);
+	if (!_statIRQAsserted(video, oldStat) && _statIRQAsserted(video, video->stat)) {
+		video->p->memory.io[REG_IF] |= (1 << GB_IRQ_LCDSTAT);
+		GBUpdateIRQs(video->p);
 	}
 }