1 files changed, 44 insertions, 0 deletions
diff --git a/src/emscripten.rs b/src/emscripten.rs
new file mode 100644
index 0000000..3b9b12c
--- /dev/null
+++ b/src/emscripten.rs
@@ -0,0 +1,44 @@
+#[cfg(target_os = "emscripten")]
+pub mod emscripten {
+    use std::cell::RefCell;
+    use std::os::raw::{c_float, c_int, c_void};
+    use std::ptr::null_mut;
+
+    #[allow(non_camel_case_types)]
+    type em_callback_func = unsafe extern "C" fn();
+
+    extern "C" {
+        pub fn emscripten_set_main_loop(
+            func: em_callback_func,
+            fps: c_int,
+            simulate_infinite_loop: c_int,
+        );
+        pub fn emscripten_cancel_main_loop();
+        pub fn emscripten_get_now() -> c_float;
+    }
+
+    thread_local!(static MAIN_LOOP_CALLBACK: RefCell<*mut c_void> = RefCell::new(null_mut()));
+
+    pub fn set_main_loop_callback<F>(callback: F)
+    where
+        F: FnMut(),
+    {
+        MAIN_LOOP_CALLBACK.with(|log| {
+            *log.borrow_mut() = &callback as *const _ as *mut c_void;
+        });
+
+        unsafe {
+            emscripten_set_main_loop(wrapper::<F>, 0, 1);
+        }
+
+        unsafe extern "C" fn wrapper<F>()
+        where
+            F: FnMut(),
+        {
+            MAIN_LOOP_CALLBACK.with(|z| {
+                let closure = *z.borrow_mut() as *mut F;
+                (*closure)();
+            });
+        }
+    }
+}