1 files changed, 52 insertions, 0 deletions
diff --git a/src/runtime.js b/src/runtime.js
index 0e4b7b2d..fe6481f5 100644
--- a/src/runtime.js
+++ b/src/runtime.js
@@ -313,7 +313,59 @@ var Runtime = {
     FUNCTION_TABLE.push(func);
     FUNCTION_TABLE.push(0);
     return ret;
+  },
+
+#if RUNTIME_DEBUG
+  debug: false, // Switch to true at runtime to enable logging at the right times
+
+  printObjectMap: null,
+  printObjectCounter: 1,
+
+  prettyPrint: function(arg) {
+    if (!Runtime.printObjectMap) Runtime.printObjectMap = new WeakMap();
+    if (typeof arg == 'undefined') return '!UNDEFINED!';
+    if (!arg) return arg;
+    if (Runtime.printObjectMap[arg]) return '<' + arg + '|' + Runtime.printObjectMap[arg] + '>';
+    if (arg.toString() == '[object HTMLImageElement]') {
+      return arg + '\n\n';
+    }
+    if (arg.byteLength) {
+      return '{' + Array.prototype.slice.call(arg, 0, Math.min(arg.length, 40)) + '}'; // Useful for correct arrays, less so for compiled arrays, see the code below for that
+      var buf = new ArrayBuffer(32);
+      var i8buf = new Int8Array(buf);
+      var i16buf = new Int16Array(buf);
+      var f32buf = new Float32Array(buf);
+      switch(arg.toString()) {
+        case '[object Uint8Array]':
+          i8buf.set(arg.subarray(0, 32));
+          break;
+        case '[object Float32Array]':
+          f32buf.set(arg.subarray(0, 5));
+          break;
+        case '[object Uint16Array]':
+          i16buf.set(arg.subarray(0, 16));
+          break;
+        default:
+          alert('unknown array for debugging: ' + arg);
+          throw 'see alert';
+      }
+      var ret = '{' + arg.byteLength + ':\n';
+      var arr = Array.prototype.slice.call(i8buf);
+      ret += 'i8:' + arr.toString().replace(/,/g, ',') + '\n';
+      arr = Array.prototype.slice.call(f32buf, 0, 8);
+      ret += 'f32:' + arr.toString().replace(/,/g, ',') + '}';
+      return ret;
+    }
+    if (typeof arg == 'object') {
+      Runtime.printObjectMap[arg] = Runtime.printObjectCounter++;
+      return '<' + arg + '|' + Runtime.printObjectMap[arg] + '>';
+    }
+    if (typeof arg == 'number') {
+      return '0x' + arg.toString(16);
+    }
+    return arg;
   }
+#endif
 };
 
 Runtime.stackAlloc = unInline('stackAlloc', ['size']);