add emscripten_async_call

src/library_browser.js

@@ -19,6 +19,13 @@ mergeInto(LibraryManager.library, {
     _emscripten_set_main_loop.cancel = true;
   },
 
+  emscripten_async_call: function(func, millis) {
+    // TODO: cache these to avoid generating garbage
+    setTimeout(function() {
+      FUNCTION_TABLE[func]();
+    }, millis);
+  },
+
   $Browser: {
     createContext: function(canvas, useWebGL) {
 #if !USE_TYPED_ARRAYS

system/include/emscripten.h

@@ -27,6 +27,21 @@ extern int emscripten_run_script_int(const char *script);
 extern void emscripten_set_main_loop(void (*func)(), int fps);
 extern void emscripten_cancel_main_loop();
 
+/*
+ * Call a C function asynchronously, that is, after returning
+ * control to the JS event loop. This is done by a setTimeout.
+ * When building natively this becomes a simple direct call,
+ * after SDL_Delay (you must include SDL.h for that).
+ */
+#if EMSCRIPTEN
+extern void emscripten_async_call(void (*func)(), int millis);
+#else
+void emscripten_async_call(void (*func)(), int millis) {
+  SDL_Delay(millis);
+  func();
+}
+#endif
+
 /*
  * This macro-looking function will cause Emscripten to
  * generate a comment in the generated code.

tests/emscripten_api_browser.cpp

@@ -0,0 +1,38 @@
+#include<stdio.h>
+#include<math.h>
+#include<SDL.h>
+#include<emscripten.h>
+#include<assert.h>
+
+int last = 0;
+
+extern "C" {
+
+void third() {
+  int now = SDL_GetTicks();
+  printf("thard! %d\n", now);
+  assert(fabs(now - last - 1000) < 500);
+  int result = 1;
+  REPORT_RESULT();
+}
+
+void second() {
+  int now = SDL_GetTicks();
+  printf("sacond! %d\n", now);
+  assert(fabs(now - last - 500) < 250);
+  last = now;
+  emscripten_async_call(third, 1000);
+}
+
+}
+
+int main() {
+  SDL_Init(0);
+  last = SDL_GetTicks();
+  printf("frist! %d\n", last);
+
+  emscripten_async_call(second, 500);
+
+  return 1;
+}
+

tests/runner.py

@@ -7163,6 +7163,11 @@ elif 'browser' in str(sys.argv):
         Popen(['python', EMCC, program, '-o', 'program.html', '--pre-js', 'reftest.js'] + args).communicate()
         self.run_browser('program.html', '', '/report_result?0')
 
+    def test_emscripten_api(self):
+      open(os.path.join(self.get_dir(), 'main.cpp'), 'w').write(self.with_report_result(open(path_from_root('tests', 'emscripten_api_browser.cpp')).read()))
+      Popen(['python', EMCC, os.path.join(self.get_dir(), 'main.cpp'), '-o', 'page.html']).communicate()
+      self.run_browser('page.html', '', '/report_result?1')
+
 elif 'benchmark' in str(sys.argv):
   # Benchmarks. Run them with argument |benchmark|. To run a specific test, do
   # |benchmark.test_X|.