From b3090678a9d9d1a8bda18a1781557d0547882da9 Mon Sep 17 00:00:00 2001
From: Linus Groh <mail@linusgroh.de>
Date: Mon, 18 May 2020 16:04:38 +0100
Subject: [PATCH] LibJS: Add Math.clz32()

---
 Libraries/LibJS/Runtime/MathObject.cpp | 12 +++++++
 Libraries/LibJS/Runtime/MathObject.h   |  1 +
 Libraries/LibJS/Tests/Math.clz32.js    | 50 ++++++++++++++++++++++++++
 3 files changed, 63 insertions(+)
 create mode 100644 Libraries/LibJS/Tests/Math.clz32.js

diff --git a/Libraries/LibJS/Runtime/MathObject.cpp b/Libraries/LibJS/Runtime/MathObject.cpp
index 2b173bcc701..73ee7696c0d 100644
--- a/Libraries/LibJS/Runtime/MathObject.cpp
+++ b/Libraries/LibJS/Runtime/MathObject.cpp
@@ -1,5 +1,6 @@
 /*
  * Copyright (c) 2020, Andreas Kling <kling@serenityos.org>
+ * Copyright (c) 2020, Linus Groh <mail@linusgroh.de>
  * All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
@@ -53,6 +54,7 @@ MathObject::MathObject()
     put_native_function("exp", exp, 1, attr);
     put_native_function("expm1", expm1, 1, attr);
     put_native_function("sign", sign, 1, attr);
+    put_native_function("clz32", clz32, 1, attr);
 
     put("E", Value(M_E), 0);
     put("LN2", Value(M_LN2), 0);
@@ -245,4 +247,14 @@ Value MathObject::sign(Interpreter& interpreter)
     return js_nan();
 }
 
+Value MathObject::clz32(Interpreter& interpreter)
+{
+    auto number = interpreter.argument(0).to_number(interpreter);
+    if (interpreter.exception())
+        return {};
+    if (!number.is_finite_number() || (unsigned)number.as_double() == 0)
+        return Value(32);
+    return Value(__builtin_clz((unsigned)number.as_double()));
+}
+
 }
diff --git a/Libraries/LibJS/Runtime/MathObject.h b/Libraries/LibJS/Runtime/MathObject.h
index e9902e6d53d..1cd550ca7dc 100644
--- a/Libraries/LibJS/Runtime/MathObject.h
+++ b/Libraries/LibJS/Runtime/MathObject.h
@@ -54,6 +54,7 @@ private:
     static Value exp(Interpreter&);
     static Value expm1(Interpreter&);
     static Value sign(Interpreter&);
+    static Value clz32(Interpreter&);
 };
 
 }
diff --git a/Libraries/LibJS/Tests/Math.clz32.js b/Libraries/LibJS/Tests/Math.clz32.js
new file mode 100644
index 00000000000..ee37c9212d0
--- /dev/null
+++ b/Libraries/LibJS/Tests/Math.clz32.js
@@ -0,0 +1,50 @@
+load("test-common.js");
+
+try {
+    assert(Math.clz32.length === 1);
+
+    assert(Math.clz32(0) === 32);
+    assert(Math.clz32(1) === 31);
+    assert(Math.clz32(2) === 30);
+    assert(Math.clz32(3) === 30);
+    assert(Math.clz32(4) === 29);
+    assert(Math.clz32(5) === 29);
+    assert(Math.clz32(-1) === 0);
+    assert(Math.clz32(-10) === 0);
+    assert(Math.clz32(-100) === 0);
+    assert(Math.clz32(-1000) === 0);
+    assert(Math.clz32(-0.123) === 32);
+    assert(Math.clz32(0.123) === 32);
+    assert(Math.clz32(1.23) === 31);
+    assert(Math.clz32(12) === 28);
+    assert(Math.clz32(123) === 25);
+    assert(Math.clz32(1234) === 21);
+    assert(Math.clz32(12345) === 18);
+    assert(Math.clz32(123456) === 15);
+    assert(Math.clz32(1234567) === 11);
+    assert(Math.clz32(12345678) === 8);
+    assert(Math.clz32(123456789) === 5);
+    assert(Math.clz32(999999999) === 2);
+    assert(Math.clz32(9999999999) === 1);
+    assert(Math.clz32(99999999999) === 1);
+    assert(Math.clz32(999999999999) === 0);
+    assert(Math.clz32(9999999999999) === 1);
+    assert(Math.clz32(99999999999999) === 3);
+    assert(Math.clz32(999999999999999) === 0);
+
+    assert(Math.clz32() === 32);
+    assert(Math.clz32(NaN) === 32);
+    assert(Math.clz32(Infinity) === 32);
+    assert(Math.clz32(-Infinity) === 32);
+    assert(Math.clz32(false) === 32);
+    assert(Math.clz32(true) === 31);
+    assert(Math.clz32(null) === 32);
+    assert(Math.clz32(undefined) === 32);
+    assert(Math.clz32([]) === 32);
+    assert(Math.clz32({}) === 32);
+    assert(Math.clz32("foo") === 32);
+
+    console.log("PASS");
+} catch (e) {
+    console.log("FAIL: " + e);
+}