M CHANGES → CHANGES

@@ -66,6 +66,7 @@ - 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
  - GB MBC: Fix swapping carts not detect new MBC
+ - GB Timer: Fix DIV batching if TAC changes
 Misc:
  - SDL: Remove scancode key input
  - GBA Video: Clean up unused timers

M src/gb/timer.c → src/gb/timer.c

@@ -9,6 +9,8 @@ #include <mgba/internal/gb/gb.h>
 #include <mgba/internal/gb/io.h>
 #include <mgba/internal/gb/serialize.h>
 
+static void _GBTimerUpdateDIV(struct GBTimer* timer, uint32_t cyclesLate);
+
 void _GBTimerIRQ(struct mTiming* timing, void* context, uint32_t cyclesLate) {
 	UNUSED(timing);
 	UNUSED(cyclesLate);
@@ -34,8 +36,12 @@ }
 		++timer->internalDiv;
 		timer->p->memory.io[REG_DIV] = timer->internalDiv >> 4;
 	}
+	_GBTimerUpdateDIV(timer, cyclesLate);
+}
+
+void _GBTimerUpdateDIV(struct GBTimer* timer, uint32_t cyclesLate) {
 	// Batch div increments
-	int divsToGo = 16 - (timer->internalDiv & 15);
+	int divsToGo = 16 - (timer->internalDiv & 15) + (timer->nextDiv / GB_DMG_DIV_PERIOD);
 	int timaToGo = INT_MAX;
 	if (timer->timaPeriod) {
 		timaToGo = timer->timaPeriod - (timer->internalDiv & (timer->timaPeriod - 1));
@@ -43,8 +49,12 @@ }
 	if (timaToGo < divsToGo) {
 		divsToGo = timaToGo;
 	}
-	timer->nextDiv = GB_DMG_DIV_PERIOD * divsToGo;
-	mTimingSchedule(timing, &timer->event, timer->nextDiv - cyclesLate);
+	if (divsToGo > 16) {
+		divsToGo = 16;
+	}
+	timer->nextDiv &= GB_DMG_DIV_PERIOD - 1;
+	timer->nextDiv += GB_DMG_DIV_PERIOD * divsToGo;
+	mTimingSchedule(&timer->p->timing, &timer->event, timer->nextDiv - cyclesLate);
 }
 
 void GBTimerReset(struct GBTimer* timer) {
@@ -89,6 +99,8 @@ }
 	} else {
 		timer->timaPeriod = 0;
 	}
+	mTimingDeschedule(&timer->p->timing, &timer->event);
+	_GBTimerUpdateDIV(timer, 0);
 	return tac;
 }