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Serenity Operating System
1/*
2 * Copyright (c) 2022, Dan Klishch <danilklishch@gmail.com>
3 *
4 * SPDX-License-Identifier: BSD-2-Clause
5 */
6
7#pragma once
8
9#ifdef KERNEL
10# error This file should not be included in the KERNEL, as doubles should not appear in the \
11 kernel code, although the conversion currently does not use any floating point \
12 computations.
13#endif
14
15#include <AK/Concepts.h>
16#include <AK/Types.h>
17
18namespace AK {
19
20struct FloatingPointExponentialForm {
21 bool sign;
22 u64 fraction;
23 i32 exponent;
24};
25
26/// This function finds the representation of `value' in the form of
27/// `(-1) ^ sign * fraction * 10 ^ exponent', such that (applying in the order of enumeration):
28///
29/// 1. sign is either 0 or 1, fraction is a non-negative number, exponent is an integer.
30/// 2. For +0, it is {.sign = 0, .fraction = 0, .exponent = 0},
31/// for -0, is {.sign = 1, .fraction = 0, .exponent = 0},
32/// for +inf, -inf, and NaN is undefined.
33/// 3. `(-1) ^ sign * fraction * 10 ^ exponent', computed with an infinite precision, rounds to
34/// `value' in the half to even mode.
35/// 4. len(str(fraction)) is minimal.
36/// 5. `abs((-1) ^ sign * fraction * 10 ^ exponent - value)' is minimal.
37/// 6. fraction is even.
38template<FloatingPoint T>
39FloatingPointExponentialForm convert_floating_point_to_decimal_exponential_form(T value);
40
41}
42
43#if USING_AK_GLOBALLY
44using AK::convert_floating_point_to_decimal_exponential_form;
45#endif