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LibJS: Add spec comments and check for edge cases in Math.log2

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davidot 2022-11-28 12:05:58 +01:00 • committed by Andreas Kling
parent 4813385c9a
commit eda90b54d4
2 changed files with 23 additions and 3 deletions
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23
Userland/Libraries/LibJS/Runtime/MathObject.cpp
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@ -548,10 +548,27 @@ JS_DEFINE_NATIVE_FUNCTION(MathObject::log)
// 21.3.2.23 Math.log2 ( x ), https://tc39.es/ecma262/#sec-math.log2
JS_DEFINE_NATIVE_FUNCTION(MathObject::log2)
{
auto value = TRY(vm.argument(0).to_number(vm)).as_double();
if (value < 0)
// 1. Let n be ? ToNumber(x).
auto number = TRY(vm.argument(0).to_number(vm));
// 2. If n is NaN or n is +∞𝔽, return n.
if (number.is_nan() || number.is_positive_infinity())
return number;
// 3. If n is 1𝔽, return +0𝔽.
if (number.as_double() == 1.)
return Value(0);
// 4. If n is +0𝔽 or n is -0𝔽, return -∞𝔽.
if (number.is_positive_zero() || number.is_negative_zero())
return js_negative_infinity();
// 5. If n < -0𝔽, return NaN.
if (number.as_double() < -0.)
return js_nan();
return Value(::log2(value));
// 6. Return an implementation-approximated Number value representing the result of the base 2 logarithm of ℝ(n).
return Value(::log2(number.as_double()));
}
// 21.3.2.22 Math.log10 ( x ), https://tc39.es/ecma262/#sec-math.log10