add a version of emscripten_set_main_loop where the main loop takes an argument; fixes #2114

3 files changed, 29 insertions, 4 deletions

diff --git a/src/library_browser.js b/src/library_browser.js
index 50a8fc6f..46082281 100644
--- a/src/library_browser.js
+++ b/src/library_browser.js
@@ -752,7 +752,7 @@ mergeInto(LibraryManager.library, {
     document.body.appendChild(script);
   },
 
-  emscripten_set_main_loop: function(func, fps, simulateInfiniteLoop) {
+  emscripten_set_main_loop: function(func, fps, simulateInfiniteLoop, arg) {
     Module['noExitRuntime'] = true;
 
     Browser.mainLoop.runner = function Browser_mainLoop_runner() {
@@ -803,7 +803,11 @@ mergeInto(LibraryManager.library, {
       }
 
       try {
-        Runtime.dynCall('v', func);
+        if (typeof arg !== 'undefined') {
+          Runtime.dynCall('vi', func, [arg]);
+        } else {
+          Runtime.dynCall('v', func);
+        }
       } catch (e) {
         if (e instanceof ExitStatus) {
           return;
@@ -843,6 +847,11 @@ mergeInto(LibraryManager.library, {
     }
   },
 
+  emscripten_set_main_loop_arg__deps: ['emscripten_set_main_loop'],
+  emscripten_set_main_loop_arg: function(func, arg, fps, simulateInfiniteLoop) {
+    _emscripten_set_main_loop(func, fps, simulateInfiniteLoop, arg);
+  },
+
   emscripten_cancel_main_loop: function() {
     Browser.mainLoop.scheduler = null;
     Browser.mainLoop.shouldPause = true;
diff --git a/system/include/emscripten/emscripten.h b/system/include/emscripten/emscripten.h
index 426206c4..b92d920c 100644
--- a/system/include/emscripten/emscripten.h
+++ b/system/include/emscripten/emscripten.h
@@ -116,6 +116,9 @@ extern void emscripten_async_load_script(const char *script, void (*onload)(), v
  * asynchronous callbacks, but you must pause the main
  * loop until they complete.
  *
+ * If you want your main loop function to receive a void*
+ * argument, use emscripten_set_main_loop_arg.
+
  * @simulate_infinite_loop If true, this function will throw an
  *    exception in order to stop execution of the caller. This
  *    will lead to the main loop being entered instead of code
@@ -134,6 +137,7 @@ extern void emscripten_async_load_script(const char *script, void (*onload)(), v
  */
 #if EMSCRIPTEN
 extern void emscripten_set_main_loop(void (*func)(), int fps, int simulate_infinite_loop);
+extern void emscripten_set_main_loop_arg(void (*func)(void*), void *arg, int fps, int simulate_infinite_loop);
 extern void emscripten_pause_main_loop();
 extern void emscripten_resume_main_loop();
 extern void emscripten_cancel_main_loop();
diff --git a/tests/emscripten_api_browser.cpp b/tests/emscripten_api_browser.cpp
index 18046ca3..a03b71ed 100644
--- a/tests/emscripten_api_browser.cpp
+++ b/tests/emscripten_api_browser.cpp
@@ -31,6 +31,18 @@ void five(void *arg) {
   emscripten_resume_main_loop();
 }
 
+void argey(void* arg) {
+  static int counter = 0;
+  assert((int)arg == 17);
+  counter++;
+  printf("argey: %d\n", counter);
+  if (counter == 5) {
+    emscripten_cancel_main_loop();
+    int result = 1;
+    REPORT_RESULT();
+  }
+}
+
 void mainey() {
   static int counter = 0;
   printf("mainey: %d\n", counter++);
@@ -45,8 +57,8 @@ void mainey() {
     assert(pre1ed);
     assert(pre2ed);
     printf("Good!\n");
-    int result = 1;
-    REPORT_RESULT();
+    emscripten_cancel_main_loop();
+    emscripten_set_main_loop_arg(argey, (void*)17, 0, 0);
   }
 }