--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/libmlk-core/mlk/core/game.c	Sat Oct 15 20:23:14 2022 +0200
@@ -0,0 +1,140 @@
+/*
+ * game.c -- main game object
+ *
+ * Copyright (c) 2020-2022 David Demelier <markand@malikania.fr>
+ *
+ * Permission to use, copy, modify, and/or distribute this software for any
+ * purpose with or without fee is hereby granted, provided that the above
+ * copyright notice and this permission notice appear in all copies.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
+ * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
+ * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
+ * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
+ * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
+ * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
+ * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
+ */
+
+#include <assert.h>
+#include <string.h>
+
+#include "clock.h"
+#include "event.h"
+#include "game.h"
+#include "state.h"
+#include "util.h"
+#include "window.h"
+
+struct game game = {0};
+
+void
+game_init(struct state **states, size_t statesz)
+{
+	assert(states);
+	assert(statesz);
+
+	memset(&game, 0, sizeof (game));
+
+	game.states = states;
+	game.statesz = statesz;
+
+	for (size_t i = 0; i < game.statesz; ++i)
+		game.states[i] = NULL;
+}
+
+void
+game_push(struct state *state)
+{
+	assert(state);
+	assert(!game.state || game.state != &game.states[game.statesz - 1]);
+
+	if (!game.state) {
+		game.state = &game.states[0];
+		state_start(*game.state = state);
+	} else {
+		state_suspend(*game.state);
+		state_start(*(++game.state) = state);
+	}
+}
+
+void
+game_pop(void)
+{
+	assert(game.state);
+
+	state_end(*game.state);
+	state_finish(*game.state);
+
+	if (game.state == game.states)
+		game.state = NULL;
+	else
+		state_resume(*--game.state);
+}
+
+void
+game_handle(const union event *ev)
+{
+	assert(ev);
+
+	if (*game.state && !(game.inhibit & INHIBIT_STATE_INPUT))
+		state_handle(*game.state, ev);
+}
+
+void
+game_update(unsigned int ticks)
+{
+	if (*game.state && !(game.inhibit & INHIBIT_STATE_UPDATE))
+		state_update(*game.state, ticks);
+}
+
+void
+game_draw(void)
+{
+	if (*game.state && !(game.inhibit & INHIBIT_STATE_DRAW))
+		state_draw(*game.state);
+}
+
+void
+game_loop(void)
+{
+	struct mlk_clock clock = {0};
+	unsigned int elapsed = 0;
+	unsigned int frametime;
+
+	if (window.framerate > 0)
+		frametime = 1000 / window.framerate;
+	else
+		/* Assuming 50.0 FPS. */
+		frametime = 1000.0 / 50.0;
+
+	while (*game.state) {
+		mlk_clock_start(&clock);
+
+		for (union event ev; event_poll(&ev); )
+			game_handle(&ev);
+
+		game_update(elapsed);
+		game_draw();
+
+		/*
+		 * If vsync is enabled, it should have wait, otherwise sleep
+		 * a little to save CPU cycles.
+		 */
+		if ((elapsed = mlk_clock_elapsed(&clock)) < frametime)
+			util_delay(frametime - elapsed);
+
+		elapsed = mlk_clock_elapsed(&clock);
+	}
+}
+
+void
+game_quit(void)
+{
+	for (size_t i = 0; i < game.statesz; ++i) {
+		if (game.states[i])
+			state_finish(game.states[i]);
+
+		game.states[i] = NULL;
+	}
+}