azur: add main loop support in gint

azur/CMakeLists.txt

@@ -35,6 +35,11 @@ if(AZUR_TOOLKIT_SDL AND AZUR_GRAPHICS_OPENGL)
     DEPENDS gen_glsl.py ${ASSETS})
 endif()
 
+if(AZUR_TOOLKIT_GINT)
+  list(APPEND SOURCES
+    src/gint/init.cpp)
+endif()
+
 # gint rendering
 if(AZUR_GRAPHICS_GINT_CG)
   list(APPEND SOURCES

azur/src/gint/init.cpp

@@ -0,0 +1,98 @@
+#include <azur/azur.h>
+#include <azur/log.h>
+#include <gint/timer.h>
+#include <gint/cpu.h>
+
+int azur_init(char const *title, int window_width, int window_height)
+{
+    (void)title;
+    (void)window_width;
+    (void)window_height;
+    return 0;
+}
+
+__attribute__((destructor))
+void azur_quit(void)
+{
+}
+
+//---
+// Main loop setup
+//---
+
+/* Time spent in the main loop (seconds)
+   TODO: Handle ml_time (also in the SDL backend) */
+static double ml_time = 0.0;
+/* Timers for render and updates */
+static int ml_timer_render = -1;
+static int ml_timer_update = -1;
+
+static int set_flag(volatile int *flag)
+{
+    *flag = 1;
+    return TIMER_CONTINUE;
+}
+
+int azur_main_loop(
+    void (*render)(void), int render_fps,
+    int (*update)(void), int update_ups,
+    int flags)
+{
+    volatile int render_tick = 1;
+    volatile int update_tick = 0;
+    bool started = false;
+
+    ml_timer_render = timer_configure(TIMER_ANY, 1000000 / render_fps,
+        GINT_CALL(set_flag, &render_tick));
+    if(ml_timer_render < 0) {
+        azlog(ERROR, "failed to create render timer\n");
+        return 1;
+    }
+    else {
+        timer_start(ml_timer_render);
+    }
+
+    if(!(flags & AZUR_MAIN_LOOP_TIED)) {
+        ml_timer_update = timer_configure(TIMER_ANY, 1000000 / update_ups,
+            GINT_CALL(set_flag, &update_tick));
+        if(ml_timer_update < 0) {
+            timer_stop(ml_timer_render);
+            azlog(ERROR, "failed to create render timer\n");
+            return 1;
+        }
+        else {
+            timer_start(ml_timer_update);
+        }
+    }
+
+    while(1) {
+        if(update_tick && !(flags & AZUR_MAIN_LOOP_TIED)) {
+            update_tick = 0;
+            if(update && update()) break;
+        }
+
+        if(render_tick) {
+            render_tick = 0;
+
+            /* Tied renders and updates */
+            if(started && (flags & AZUR_MAIN_LOOP_TIED)) {
+                if(update && update()) break;
+            }
+            if(render) render();
+            started = true;
+        }
+
+        sleep();
+    }
+
+    if(ml_timer_render >= 0) {
+        timer_stop(ml_timer_render);
+        ml_timer_render = 0;
+    }
+    if(ml_timer_update >= 0) {
+        timer_stop(ml_timer_update);
+        ml_timer_update = 0;
+    }
+
+    return 0;
+}

azur/src/gl/init.cpp

@@ -134,7 +134,8 @@ SDL_Window *azur_sdl_window(void)
 // Main loop setup
 //---
 
-/* Time spent in the main loop (seconds) */
+/* Time spent in the main loop (seconds)
+   TODO: Handle ml_time (also in the gint backend) */
 static double ml_time = 0.0;
 
 /* In emscripten, callbacks are void/void, vsync is always ON, and the