GBA Timers: Cascading timers don't tick when disabled (fixes #2812)

mgba-emu · Feb 3, 2023 · 4738e55 · 4738e55
1 parent 1f2df26
commit 4738e55
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Showing 2 changed files with 2 additions and 1 deletion.
diff --git a/CHANGES b/CHANGES
@@ -3,6 +3,7 @@ Emulation fixes:
  - GBA Audio: Fix improperly deserializing GB audio registers (fixes mgba.io/i/2793)
  - GBA Memory: Make VRAM access stalls only apply to BG RAM
  - GBA SIO: Fix SIOCNT SI pin value after attaching player 2 (fixes mgba.io/i/2805)
+ - GBA Timers: Cascading timers don't tick when disabled (fixes mgba.io/i/2812)
 Other fixes:
  - Core: Allow sending thread requests to a crashed core (fixes mgba.io/i/2784)
  - Qt: Fix crash when attempting to use OpenGL 2.1 to 3.1 (fixes mgba.io/i/2794)

diff --git a/src/gba/timer.c b/src/gba/timer.c
@@ -34,7 +34,7 @@ static void GBATimerUpdate(struct GBA* gba, int timerId, uint32_t cyclesLate) {
 
 	if (timerId < 3) {
 		struct GBATimer* nextTimer = &gba->timers[timerId + 1];
-		if (GBATimerFlagsIsCountUp(nextTimer->flags)) { // TODO: Does this increment while disabled?
+		if (GBATimerFlagsIsCountUp(nextTimer->flags) && GBATimerFlagsIsEnable(nextTimer->flags)) {
 			++gba->memory.io[REG_TMCNT_LO(timerId + 1) >> 1];
 			if (!gba->memory.io[REG_TMCNT_LO(timerId + 1) >> 1] && GBATimerFlagsIsEnable(nextTimer->flags)) {
 				GBATimerUpdate(gba, timerId + 1, cyclesLate);