Revision: 19435
Author: [email protected]
Date: Tue Feb 18 10:49:35 2014 UTC
Log: Harmony: implement Math.clz32
[email protected], [email protected]
BUG=v8:2938
LOG=N
Review URL: https://codereview.chromium.org/169783002
http://code.google.com/p/v8/source/detail?r=19435
Added:
/branches/bleeding_edge/test/mjsunit/harmony/math-clz32.js
Modified:
/branches/bleeding_edge/src/harmony-math.js
=======================================
--- /dev/null
+++ /branches/bleeding_edge/test/mjsunit/harmony/math-clz32.js Tue Feb 18
10:49:35 2014 UTC
@@ -0,0 +1,28 @@
+// Copyright 2014 the V8 project authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+// Flags: --harmony-maths
+
+[NaN, Infinity, -Infinity, 0, -0, "abc", "Infinity", "-Infinity",
{}].forEach(
+ function(x) {
+ assertEquals(32, Math.clz32(x));
+ }
+);
+
+function testclz(x) {
+ for (var i = 0; i < 33; i++) {
+ if (x & 0x80000000) return i;
+ x <<= 1;
+ }
+ return 32;
+}
+
+var max = Math.pow(2, 40);
+for (var x = 0; x < max; x = x * 1.01 + 1) {
+ assertEquals(testclz(x), Math.clz32(x));
+ assertEquals(testclz(-x), Math.clz32(-x));
+ assertEquals(testclz(x), Math.clz32({ valueOf: function() { return x; }
}));
+ assertEquals(testclz(-x),
+ Math.clz32({ toString: function() { return -x; } }));
+}
=======================================
--- /branches/bleeding_edge/src/harmony-math.js Tue Feb 18 10:43:06 2014 UTC
+++ /branches/bleeding_edge/src/harmony-math.js Tue Feb 18 10:49:35 2014 UTC
@@ -158,6 +158,20 @@
function MathFround(x) {
return %Math_fround(TO_NUMBER_INLINE(x));
}
+
+
+function MathClz32(x) {
+ x = ToUint32(TO_NUMBER_INLINE(x));
+ if (x == 0) return 32;
+ var result = 0;
+ // Binary search.
+ if ((x & 0xFFFF0000) === 0) { x <<= 16; result += 16; };
+ if ((x & 0xFF000000) === 0) { x <<= 8; result += 8; };
+ if ((x & 0xF0000000) === 0) { x <<= 4; result += 4; };
+ if ((x & 0xC0000000) === 0) { x <<= 2; result += 2; };
+ if ((x & 0x80000000) === 0) { x <<= 1; result += 1; };
+ return result;
+}
function ExtendMath() {
@@ -176,8 +190,10 @@
"log10", MathLog10,
"log2", MathLog2,
"hypot", MathHypot,
- "fround", MathFround
+ "fround", MathFround,
+ "clz32", MathClz32
));
}
+
ExtendMath();
--
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