M CHANGES → CHANGES

@@ -48,6 +48,7 @@ - GBA: Fix calls to endian-independent loadstores
  - GBA Video: Fix windows not affecting sprites
  - VFS: Fix line-reading to return proper values
  - GBA Memory: Fix load/store multiple video memory waitstates
+ - GBA: Fix timing of reading from timer registers
 Misc:
  - Qt: Handle saving input settings better
  - Debugger: Free watchpoints in addition to breakpoints

M src/gba/gba.c → src/gba/gba.c

@@ -451,7 +451,8 @@
 void GBATimerUpdateRegister(struct GBA* gba, int timer) {
 	struct GBATimer* currentTimer = &gba->timers[timer];
 	if (currentTimer->enable && !currentTimer->countUp) {
-		gba->memory.io[(REG_TM0CNT_LO + (timer << 2)) >> 1] = currentTimer->oldReload + ((gba->cpu->cycles - currentTimer->lastEvent) >> currentTimer->prescaleBits);
+		// Reading this takes two cycles (1N+1I), so let's remove them preemptively
+		gba->memory.io[(REG_TM0CNT_LO + (timer << 2)) >> 1] = currentTimer->oldReload + ((gba->cpu->cycles - currentTimer->lastEvent - 2) >> currentTimer->prescaleBits);
 	}
 }