From 18d02d06f024d628cc9a2568d39a8223a0d3baae Mon Sep 17 00:00:00 2001
From: "dslomov@chromium.org"
 <dslomov@chromium.org@ce2b1a6d-e550-0410-aec6-3dcde31c8c00>
Date: Fri, 3 May 2013 09:43:44 +0000
Subject: [PATCH] Implement TypedArray.subarray method.

R=rossberg@chromium.org

Review URL: https://codereview.chromium.org/14740017

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@14537 ce2b1a6d-e550-0410-aec6-3dcde31c8c00
---
 src/typedarray.js                   | 31 +++++++++++++++++++
 test/mjsunit/harmony/typedarrays.js | 60 +++++++++++++++++++++++++++++++++++++
 2 files changed, 91 insertions(+)

diff --git a/src/typedarray.js b/src/typedarray.js
index daade13..1040f86 100644
--- a/src/typedarray.js
+++ b/src/typedarray.js
@@ -167,6 +167,33 @@ 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);
+  }
+}
+
 
 // -------------------------------------------------------------------
 
@@ -205,6 +232,10 @@ function SetupTypedArray(arrayId, name, constructor, elementSize) {
   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.
diff --git a/test/mjsunit/harmony/typedarrays.js b/test/mjsunit/harmony/typedarrays.js
index ca76fe7..748b366 100644
--- a/test/mjsunit/harmony/typedarrays.js
+++ b/test/mjsunit/harmony/typedarrays.js
@@ -68,8 +68,16 @@ TestByteLengthNotWritable();
 
 function TestSlice(expectedResultLen, initialLen, start, end) {
   var ab = new ArrayBuffer(initialLen);
+  var a1 = new Uint8Array(ab);
+  for (var i = 0; i < a1.length; i++) {
+    a1[i] = 0xCA;
+  }
   var slice = ab.slice(start, end);
   assertSame(expectedResultLen, slice.byteLength);
+  var a2 = new Uint8Array(slice);
+  for (var i = 0; i < a2.length; i++) {
+    assertSame(0xCA, a2[i]);
+  }
 }
 
 function TestArrayBufferSlice() {
@@ -255,6 +263,58 @@ TestTypedArray(Float32Array, 4, 0.5);
 TestTypedArray(Float64Array, 8, 0.5);
 TestTypedArray(Uint8ClampedArray, 1, 0xFF);
 
+function SubarrayTestCase(constructor, item, expectedResultLen, expectedStartIndex,
+                          initialLen, start, end) {
+  var a = new constructor(initialLen);
+  var s = a.subarray(start, end);
+  assertSame(constructor, s.constructor);
+  assertSame(expectedResultLen, s.length);
+  if (s.length > 0) {
+    s[0] = item;
+    assertSame(item, a[expectedStartIndex]);
+  }
+}
+
+function TestSubArray(constructor, item) {
+  SubarrayTestCase(constructor, item, 512, 512, 1024, 512, 1024);
+  SubarrayTestCase(constructor, item, 512, 512, 1024, 512);
+
+  SubarrayTestCase(constructor, item, 0, undefined, 0, 1, 20);
+  SubarrayTestCase(constructor, item, 100, 0,       100, 0, 100);
+  SubarrayTestCase(constructor, item, 100, 0,       100,  0, 1000);
+  SubarrayTestCase(constructor, item, 0, undefined, 100, 5, 1);
+
+  SubarrayTestCase(constructor, item, 1, 89,        100, -11, -10);
+  SubarrayTestCase(constructor, item, 9, 90,        100, -10, 99);
+  SubarrayTestCase(constructor, item, 0, undefined, 100, -10, 80);
+  SubarrayTestCase(constructor, item, 10,80,        100, 80, -10);
+
+  SubarrayTestCase(constructor, item, 10,90,        100, 90, "100");
+  SubarrayTestCase(constructor, item, 10,90,        100, "90", "100");
+
+  SubarrayTestCase(constructor, item, 0, undefined, 100, 90, "abc");
+  SubarrayTestCase(constructor, item, 10,0,         100, "abc", 10);
+
+  SubarrayTestCase(constructor, item, 10,0,         100, 0.96, 10.96);
+  SubarrayTestCase(constructor, item, 10,0,         100, 0.96, 10.01);
+  SubarrayTestCase(constructor, item, 10,0,         100, 0.01, 10.01);
+  SubarrayTestCase(constructor, item, 10,0,         100, 0.01, 10.96);
+
+
+  SubarrayTestCase(constructor, item, 10,90,        100, 90);
+  SubarrayTestCase(constructor, item, 10,90,        100, -10);
+}
+
+TestSubArray(Uint8Array, 0xFF);
+TestSubArray(Int8Array, -0x7F);
+TestSubArray(Uint16Array, 0xFFFF);
+TestSubArray(Int16Array, -0x7FFF);
+TestSubArray(Uint32Array, 0xFFFFFFFF);
+TestSubArray(Int32Array, -0x7FFFFFFF);
+TestSubArray(Float32Array, 0.5);
+TestSubArray(Float64Array, 0.5);
+TestSubArray(Uint8ClampedArray, 0xFF);
+
 function TestTypedArrayOutOfRange(constructor, value, result) {
   var a = new constructor(1);
   a[0] = value;
-- 
2.7.4