From c22a7a23d06621b4321ef3e79d8ea078434d1f9d Mon Sep 17 00:00:00 2001
From: Tom Schuster <evilpies@gmail.com>
Date: Fri, 11 Apr 2014 17:24:58 +0200
Subject: [PATCH] Bug 925123 - Add Math.clz32 builtin. r=till

---
 js/src/jsmath.cpp                 | 24 +++++++++++++++++++
 js/src/jsmath.h                   |  3 +++
 js/src/tests/ecma_6/Math/clz32.js | 38 +++++++++++++++++++++++++++++++
 3 files changed, 65 insertions(+)
 create mode 100644 js/src/tests/ecma_6/Math/clz32.js

diff --git a/js/src/jsmath.cpp b/js/src/jsmath.cpp
index 591985d55e8..9dd6f4a7377 100644
--- a/js/src/jsmath.cpp
+++ b/js/src/jsmath.cpp
@@ -309,6 +309,29 @@ js::math_ceil(JSContext *cx, unsigned argc, Value *vp)
     return true;
 }
 
+bool
+js::math_clz32(JSContext *cx, unsigned argc, Value *vp)
+{
+    CallArgs args = CallArgsFromVp(argc, vp);
+
+    if (args.length() == 0) {
+        args.rval().setInt32(32);
+        return true;
+    }
+
+    uint32_t n;
+    if (!ToUint32(cx, args[0], &n))
+        return false;
+
+    if (n == 0) {
+        args.rval().setInt32(32);
+        return true;
+    }
+
+    args.rval().setInt32(mozilla::CountLeadingZeroes32(n));
+    return true;
+}
+
 /*
  * Fast sine and cosine approximation code, based on the sin [0] and cos [1]
  * implementations [2] in the cephes library [3].
@@ -1535,6 +1558,7 @@ static const JSFunctionSpec math_static_methods[] = {
     JS_FN("atan",           math_atan,            1, 0),
     JS_FN("atan2",          math_atan2,           2, 0),
     JS_FN("ceil",           math_ceil,            1, 0),
+    JS_FN("clz32",          math_clz32,           1, 0),
     JS_FN("cos",            math_cos,             1, 0),
     JS_FN("exp",            math_exp,             1, 0),
     JS_FN("floor",          math_floor,           1, 0),
diff --git a/js/src/jsmath.h b/js/src/jsmath.h
index d977febaedc..997575ae383 100644
--- a/js/src/jsmath.h
+++ b/js/src/jsmath.h
@@ -247,6 +247,9 @@ math_ceil(JSContext *cx, unsigned argc, Value *vp);
 extern double
 math_ceil_impl(double x);
 
+extern bool
+math_clz32(JSContext *cx, unsigned argc, Value *vp);
+
 extern bool
 math_floor(JSContext *cx, unsigned argc, Value *vp);
 
diff --git a/js/src/tests/ecma_6/Math/clz32.js b/js/src/tests/ecma_6/Math/clz32.js
new file mode 100644
index 00000000000..769cf18fc0f
--- /dev/null
+++ b/js/src/tests/ecma_6/Math/clz32.js
@@ -0,0 +1,38 @@
+// Undefined and NaN end up as zero after ToUint32
+assertEq(Math.clz32(), 32);
+assertEq(Math.clz32(NaN), 32);
+assertEq(Math.clz32.call(), 32);
+// 0
+assertEq(Math.clz32(null), 32);
+assertEq(Math.clz32(false), 32);
+// 1
+assertEq(Math.clz32(true), 31);
+// 3
+assertEq(Math.clz32(3.5), 30);
+// NaN -> 0
+assertEq(Math.clz32({}), 32);
+// 2
+assertEq(Math.clz32({valueOf: function() { return 2; }}), 30);
+// 0 -> 0
+assertEq(Math.clz32([]), 32);
+assertEq(Math.clz32(""), 32);
+// NaN -> 0
+assertEq(Math.clz32([1, 2, 3]), 32);
+assertEq(Math.clz32("bar"), 32);
+// 15
+assertEq(Math.clz32("15"), 28);
+
+
+assertEq(Math.clz32(0x80000000), 0);
+assertEq(Math.clz32(0xF0FF1000), 0);
+assertEq(Math.clz32(0x7F8F0001), 1);
+assertEq(Math.clz32(0x3FFF0100), 2);
+assertEq(Math.clz32(0x1FF50010), 3);
+assertEq(Math.clz32(0x00800000), 8);
+assertEq(Math.clz32(0x00400000), 9);
+assertEq(Math.clz32(0x00008000), 16);
+assertEq(Math.clz32(0x00004000), 17);
+assertEq(Math.clz32(0x00000080), 24);
+assertEq(Math.clz32(0x00000040), 25);
+assertEq(Math.clz32(0x00000001), 31);
+assertEq(Math.clz32(0), 32);