GBA: Ensure cycles never go negative

CHANGES

@@ -71,6 +71,7 @@ Bugfixes:
  - Qt: Fix passing command line options
  - Qt: Fix crashes on Windows by using using QMetaObject to do cross-thread calls
  - GBA Video: Fix timing on first scanline
+ - GBA: Ensure cycles never go negative
 Misc:
  - Qt: Handle saving input settings better
  - Debugger: Free watchpoints in addition to breakpoints

src/gba/gba.c

@@ -184,6 +184,11 @@ static void GBAProcessEvents(struct ARMCore* cpu) {
 		int32_t cycles = cpu->nextEvent;
 		int32_t nextEvent = INT_MAX;
 		int32_t testEvent;
+#ifndef NDEBUG
+		if (cycles < 0) {
+			GBALog(gba, GBA_LOG_FATAL, "Negative cycles passed: %i", cycles);
+		}
+#endif
 
 		gba->bus = cpu->prefetch[1];
 		if (cpu->executionMode == MODE_THUMB) {

src/gba/serialize.c

@@ -87,6 +87,10 @@ bool GBADeserialize(struct GBA* gba, const struct GBASerializedState* state) {
 		GBALog(gba, GBA_LOG_WARN, "Savestate is corrupted: CPU cycles are negative");
 		error = true;
 	}
+	if (state->cpu.nextEvent < 0) {
+		GBALog(gba, GBA_LOG_WARN, "Savestate is corrupted: Next event is negative");
+		error = true;
+	}
 	if (state->video.eventDiff < 0) {
 		GBALog(gba, GBA_LOG_WARN, "Savestate is corrupted: video eventDiff is negative");
 		error = true;