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fdc53a5995
Currently, the floating point to string conversion is implemented several times across the codebase. This commit provides a pretty low-level function to unify all of such conversions. It converts the given double to a fixed point decimal satisfying a few correctness criteria.
44 lines
1.4 KiB
C++
44 lines
1.4 KiB
C++
/*
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* Copyright (c) 2022, Dan Klishch <danilklishch@gmail.com>
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*
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* SPDX-License-Identifier: BSD-2-Clause
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*/
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#pragma once
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#ifdef KERNEL
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# error This file should not be included in the KERNEL, as doubles should not appear in the \
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kernel code, although the conversion currently does not use any floating point \
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computations.
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#endif
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#include <AK/Concepts.h>
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#include <AK/Types.h>
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namespace AK {
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struct FloatingPointExponentialForm {
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bool sign;
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u64 fraction;
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i32 exponent;
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};
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/// This function finds the representation of `value' in the form of
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/// `(-1) ^ sign * fraction * 10 ^ exponent', such that (applying in the order of enumeration):
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///
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/// 1. sign is either 0 or 1, fraction is a non-negative number, exponent is an integer.
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/// 2. For +0, it is {.sign = 0, .fraction = 0, .exponent = 0},
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/// for -0, is {.sign = 1, .fraction = 0, .exponent = 0},
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/// for +inf, -inf, and NaN is undefined.
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/// 3. `(-1) ^ sign * fraction * 10 ^ exponent', computed with an infinite precision, rounds to
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/// `value' in the half to even mode.
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/// 4. len(str(fraction)) is minimal.
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/// 5. `abs((-1) ^ sign * fraction * 10 ^ exponent - value)' is minimal.
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/// 6. fraction is even.
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template<FloatingPoint T>
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FloatingPointExponentialForm convert_floating_point_to_decimal_exponential_form(T value);
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}
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using AK::convert_floating_point_to_decimal_exponential_form;
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