Implement TypedArray.subarray method.

src/typedarray.js

 // Copyright 2013 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 149 matching lines @@
 }
 
 function TypedArrayGetByteOffset() {
   return %TypedArrayGetByteOffset(this);
 }
 
 function TypedArrayGetLength() {
   return %TypedArrayGetLength(this);
 }
 
+function CreateSubArray(elementSize, constructor) {
+  return function(begin, end) {
+    var srcLength = %TypedArrayGetLength(this);
+    var beginInt = TO_INTEGER(begin);
+    if (beginInt < 0) {
+      beginInt = MathMax(0, srcLength + beginInt);
+    } else {
+      beginInt = MathMin(srcLength, beginInt);
+    }
+
+    var endInt = IS_UNDEFINED(end) ? srcLength : TO_INTEGER(end);
+    if (endInt < 0) {
+      endInt = MathMax(0, srcLength + endInt);
+    } else {
+      endInt = MathMin(endInt, srcLength);
+    }
+    if (endInt < beginInt) {
+      endInt = beginInt;
+    }
+    var newLength = endInt - beginInt;
+    var beginByteOffset =
+        %TypedArrayGetByteOffset(this) + beginInt * elementSize;
+    return new constructor(%TypedArrayGetBuffer(this),
+                           beginByteOffset, newLength);
+  }
+}
+
 
 // -------------------------------------------------------------------
 
 function SetUpArrayBuffer() {
   %CheckIsBootstrapping();
 
   // Set up the ArrayBuffer constructor function.
   %SetCode($ArrayBuffer, ArrayBufferConstructor);
   %FunctionSetPrototype($ArrayBuffer, new $Object());
 
@@ skipping 18 matching lines @@
 
   %SetProperty(constructor.prototype,
                "constructor", constructor, DONT_ENUM);
   %SetProperty(constructor.prototype,
                "BYTES_PER_ELEMENT", elementSize,
                READ_ONLY | DONT_ENUM | DONT_DELETE);
   InstallGetter(constructor.prototype, "buffer", TypedArrayGetBuffer);
   InstallGetter(constructor.prototype, "byteOffset", TypedArrayGetByteOffset);
   InstallGetter(constructor.prototype, "byteLength", TypedArrayGetByteLength);
   InstallGetter(constructor.prototype, "length", TypedArrayGetLength);
+
+  InstallFunctions(constructor.prototype, DONT_ENUM, $Array(
+        "subarray", CreateSubArray(elementSize, constructor)
+  ));
 }
 
 // arrayIds below should be synchronized with Runtime_TypedArrayInitialize.
 SetupTypedArray(1, "Uint8Array", global.Uint8Array, 1);
 SetupTypedArray(2, "Int8Array", global.Int8Array, 1);
 SetupTypedArray(3, "Uint16Array", global.Uint16Array, 2);
 SetupTypedArray(4, "Int16Array", global.Int16Array, 2);
 SetupTypedArray(5, "Uint32Array", global.Uint32Array, 4);
 SetupTypedArray(6, "Int32Array", global.Int32Array, 4);
 SetupTypedArray(7, "Float32Array", global.Float32Array, 4);
 SetupTypedArray(8, "Float64Array", global.Float64Array, 8);
 SetupTypedArray(9, "Uint8ClampedArray", global.Uint8ClampedArray, 1);