emscripten_get_now

2 files changed, 17 insertions, 0 deletions

diff --git a/src/library_browser.js b/src/library_browser.js
index c42cef14..d49c4103 100644
--- a/src/library_browser.js
+++ b/src/library_browser.js
@@ -241,6 +241,14 @@ mergeInto(LibraryManager.library, {
       }
     }
     styleSheet.insertRule('canvas.emscripten { border: 1px solid black; cursor: none; }', 0);
+  },
+
+  emscripten_get_now: function() {
+    if (window['performance'] && window['performance']['now']) {
+      return window['performance']['now']();
+    } else {
+      return Date.now();
+    }
   }
 });
 
diff --git a/system/include/emscripten.h b/system/include/emscripten.h
index a4f15868..d0e6cc46 100644
--- a/system/include/emscripten.h
+++ b/system/include/emscripten.h
@@ -65,6 +65,15 @@ void emscripten_async_call(void (*func)(), int millis) {
 void emscripten_hide_mouse();
 
 /*
+ * Returns the highest-precision representation of the
+ * current time that the browser provides. This uses either
+ * Date.now or performance.now. The result is *not* an
+ * absolute time, and is only meaningful in comparison to
+ * other calls to this function. The unit is ms.
+ */
+float emscripten_get_now();
+
+/*
  * This macro-looking function will cause Emscripten to
  * generate a comment in the generated code.
  * XXX This is deprecated for now, because it requires us to