[nostalgia/core/gba] Fix event cycle and add to setter for event handler

src/nostalgia/core/gba/core.arm.cpp

@@ -0,0 +1,45 @@
+/*
+ * Copyright 2016 - 2020 gary@drinkingtea.net
+ *
+ * This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/.
+ */
+
+#include <nostalgia/core/config.hpp>
+#include <nostalgia/core/core.hpp>
+
+#include "addresses.hpp"
+#include "bios.hpp"
+#include "irq.hpp"
+
+extern "C" void isr();
+
+namespace nostalgia::core {
+
+extern volatile gba_timer_t g_timerMs;
+gba_timer_t g_wakeupTime;
+event_handler g_eventHandler = nullptr;
+
+ox::Error run(Context*) {
+	g_wakeupTime = 0;
+	while (1) {
+		if (g_wakeupTime <= g_timerMs && g_eventHandler) {
+			auto sleepTime = g_eventHandler();
+			if (sleepTime >= 0) {
+				g_wakeupTime = g_timerMs + static_cast<unsigned>(sleepTime);
+			} else {
+				g_wakeupTime = ~gba_timer_t(0);
+			}
+		}
+		if constexpr(config::GbaEventLoopTimerBased) {
+			// wait for timer interrupt
+			nostalgia_core_intrwait(0, Int_timer0 | Int_timer1 | Int_timer2 | Int_timer3);
+		} else {
+			nostalgia_core_vblankintrwait();
+		}
+	}
+	return OxError(0);
+}
+
+}