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LibJS: Implement BigInt.asUintN

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This commit is contained in:
Timothy Flynn 2022-02-05 21:04:17 -05:00 • committed by Linus Groh
parent 460c2caaf7
commit cb57475168
2 changed files with 88 additions and 2 deletions
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13
Userland/Libraries/LibJS/Runtime/BigIntConstructor.cpp
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@ -32,7 +32,7 @@ void BigIntConstructor::initialize(GlobalObject& global_object)
u8 attr = Attribute::Writable | Attribute::Configurable;
define_native_function(vm.names.asIntN, as_int_n, 2, attr);
// define_native_function(vm.names.asUintN, as_uint_n, 2, attr);
define_native_function(vm.names.asUintN, as_uint_n, 2, attr);
define_direct_property(vm.names.length, Value(1), Attribute::Configurable);
}
@ -95,7 +95,16 @@ JS_DEFINE_NATIVE_FUNCTION(BigIntConstructor::as_int_n)
// 21.2.2.2 BigInt.asUintN ( bits, bigint ), https://tc39.es/ecma262/#sec-bigint.asuintn
JS_DEFINE_NATIVE_FUNCTION(BigIntConstructor::as_uint_n)
{
TODO();
// 1. Set bits to ? ToIndex(bits).
auto bits = TRY(vm.argument(0).to_index(global_object));
// 2. Set bigint to ? ToBigInt(bigint).
auto* bigint = TRY(vm.argument(1).to_bigint(global_object));
// 3. Return the BigInt value that represents ℝ(bigint) modulo 2bits.
// FIXME: For large values of `bits`, this can likely be improved with a SignedBigInteger API to
// drop the most significant bits.
return js_bigint(vm, modulo(bigint->big_integer(), BIGINT_ONE.shift_left(bits)));
}
}