@@ -28,6 +28,7 @@ - Undo-able savestate loading and saving
  - Controller profiles now store shortcut settings
  - Default controller profiles for several common controllers
  - Libretro now supports BIOS and rumble
+ - Implement BIOS call Stop, for sleep mode
 Bugfixes:
  - ARM7: Fix SWI and IRQ timings
  - GBA Audio: Force audio FIFOs to 32-bit

@@ -191,6 +191,9 @@ break;
 	case 0x2:
 		GBAHalt(gba);
 		break;
+	case 0x3:
+		GBAStop(gba);
+		break;
 	case 0x05:
 	// VBlankIntrWait
 	// Fall through:

@@ -82,6 +82,7 @@ gba->logHandler = 0;
 	gba->logLevel = GBA_LOG_WARN | GBA_LOG_ERROR | GBA_LOG_FATAL;
 	gba->stream = 0;
 	gba->keyCallback = 0;
+	gba->stopCallback = 0;
 
 	gba->biosChecksum = GBAChecksum(gba->memory.bios, SIZE_BIOS);
 
@@ -551,6 +552,14 @@
 void GBAHalt(struct GBA* gba) {
 	gba->cpu->nextEvent = 0;
 	gba->cpu->halted = 1;
+}
+
+void GBAStop(struct GBA* gba) {
+	if (!gba->stopCallback) {
+		return;
+	}
+	gba->cpu->nextEvent = 0;
+	gba->stopCallback->stop(gba->stopCallback);
 }
 
 static void _GBAVLog(struct GBA* gba, enum GBALogLevel level, const char* format, va_list args) {

@@ -112,6 +112,7 @@ GBALogHandler logHandler;
 	enum GBALogLevel logLevel;
 	struct GBAAVStream* stream;
 	struct GBAKeyCallback* keyCallback;
+	struct GBAStopCallback* stopCallback;
 
 	enum GBAIdleLoopOptimization idleOptimization;
 	uint32_t idleLoop;
@@ -155,6 +156,7 @@ void GBAWriteIME(struct GBA* gba, uint16_t value);
 void GBARaiseIRQ(struct GBA* gba, enum GBAIRQ irq);
 void GBATestIRQ(struct ARMCore* cpu);
 void GBAHalt(struct GBA* gba);
+void GBAStop(struct GBA* gba);
 
 void GBAAttachDebugger(struct GBA* gba, struct ARMDebugger* debugger);
 void GBADetachDebugger(struct GBA* gba);

@@ -66,6 +66,10 @@ struct GBAKeyCallback {
 	uint16_t (*readKeys)(struct GBAKeyCallback*);
 };
 
+struct GBAStopCallback {
+	void (*stop)(struct GBAStopCallback*);
+};
+
 struct GBARotationSource {
 	void (*sample)(struct GBARotationSource*);
 

@@ -505,7 +505,7 @@ value &= 0x80;
 		if (!value) {
 			GBAHalt(gba);
 		} else {
-			GBALog(gba, GBA_LOG_STUB, "Stop unimplemented");
+			GBAStop(gba);
 		}
 		return;
 	}