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https://github.com/SerenityOS/serenity
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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.
75 lines
3.4 KiB
C++
75 lines
3.4 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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#include <AK/BitCast.h>
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#include <AK/StringFloatingPointConversions.h>
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#include <LibTest/TestCase.h>
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static bool operator!=(AK::FloatingPointExponentialForm a, AK::FloatingPointExponentialForm b)
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{
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return a.sign != b.sign || a.exponent != b.exponent || a.fraction != b.fraction;
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}
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template<>
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struct AK::Formatter<AK::FloatingPointExponentialForm> : Formatter<FormatString> {
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ErrorOr<void> format(FormatBuilder& builder, AK::FloatingPointExponentialForm value)
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{
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return Formatter<FormatString>::format(builder, "(s={} f={} e={})"sv, value.sign, value.fraction, value.exponent);
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}
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};
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#define DOES_CONVERT_DOUBLE_TO(value, sign, fraction, exponent) \
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do { \
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EXPECT_EQ( \
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convert_floating_point_to_decimal_exponential_form(static_cast<double>(value)), \
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(AK::FloatingPointExponentialForm { sign, fraction, exponent })); \
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} while (false)
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// Tests here only check basic cases. While writing, I mostly relied on the benchmarks and
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// stress tests, which can be found at https://github.com/DanShaders/serenity-arithmetic-benchmark/blob/master/StringFloatingPointConversions.cpp .
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TEST_CASE(double_conversion)
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{
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DOES_CONVERT_DOUBLE_TO(0, 0, 0, 0);
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DOES_CONVERT_DOUBLE_TO(-0., 1, 0, 0);
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DOES_CONVERT_DOUBLE_TO(1, 0, 1, 0);
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DOES_CONVERT_DOUBLE_TO(-1, 1, 1, 0);
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DOES_CONVERT_DOUBLE_TO(.1, 0, 1, -1);
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DOES_CONVERT_DOUBLE_TO(.2, 0, 2, -1);
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DOES_CONVERT_DOUBLE_TO(.3, 0, 3, -1);
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DOES_CONVERT_DOUBLE_TO(.12345, 0, 12345, -5);
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DOES_CONVERT_DOUBLE_TO(.0012345, 0, 12345, -7);
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DOES_CONVERT_DOUBLE_TO(.1 + .2, 0, 30000000000000004, -17);
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DOES_CONVERT_DOUBLE_TO(17976931348623157e292, 0, 17976931348623157, 292);
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DOES_CONVERT_DOUBLE_TO(-17976931348623157e292, 1, 17976931348623157, 292);
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DOES_CONVERT_DOUBLE_TO(22250738585072014e-324, 0, 22250738585072014, -324);
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DOES_CONVERT_DOUBLE_TO(-22250738585072014e-324, 1, 22250738585072014, -324);
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DOES_CONVERT_DOUBLE_TO(bit_cast<double>(0xc3c04222300db8acULL), 1, 23430728857074627, 2);
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}
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#define DOES_CONVERT_FLOAT_TO(value, sign, fraction, exponent) \
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do { \
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EXPECT_EQ( \
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convert_floating_point_to_decimal_exponential_form(static_cast<float>(value)), \
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(AK::FloatingPointExponentialForm { sign, fraction, exponent })); \
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} while (false)
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TEST_CASE(float_conversion)
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{
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DOES_CONVERT_FLOAT_TO(0, 0, 0, 0);
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DOES_CONVERT_FLOAT_TO(-0., 1, 0, 0);
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DOES_CONVERT_FLOAT_TO(1, 0, 1, 0);
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DOES_CONVERT_FLOAT_TO(-1, 1, 1, 0);
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DOES_CONVERT_FLOAT_TO(.1, 0, 1, -1);
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DOES_CONVERT_FLOAT_TO(.2, 0, 2, -1);
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DOES_CONVERT_FLOAT_TO(.3, 0, 3, -1);
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DOES_CONVERT_FLOAT_TO(0.025, 0, 25, -3);
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DOES_CONVERT_FLOAT_TO(34028235e31, 0, 34028235, 31);
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DOES_CONVERT_FLOAT_TO(-34028235e31, 1, 34028235, 31);
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DOES_CONVERT_FLOAT_TO(11754944e-45, 0, 11754944, -45);
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DOES_CONVERT_FLOAT_TO(-11754944e-45, 1, 11754944, -45);
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}
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