62 lines
2.2 KiB
C++
62 lines
2.2 KiB
C++
/* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4; fill-column: 100 -*- */
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/*
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* This file is part of the LibreOffice project.
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*
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* This Source Code Form is subject to the terms of the Mozilla Public
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* License, v. 2.0. If a copy of the MPL was not distributed with this
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* file, You can obtain one at http://mozilla.org/MPL/2.0/.
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*/
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#pragma once
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#include <string>
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#include <sal/config.h>
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#include <rtl/math.hxx>
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class NanPayloadTest
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{
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private:
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bool m_bSupported = { false };
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std::string m_aMessage;
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public:
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NanPayloadTest()
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{
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// Test that a quiet NaN payload is propagated and behaves as we
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// expect. Ideally that could be done with a constexpr in
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// sal/rtl/math.cxx to fail already during compile time instead of make
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// check, but..
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// See
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// https://grouper.ieee.org/groups/msc/ANSI_IEEE-Std-754-2019/background/nan-propagation.pdf
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double fVal1 = std::numeric_limits<double>::quiet_NaN();
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reinterpret_cast<sal_math_Double*>(&fVal1)->nan_parts.fraction_lo = 0xbeef;
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const double fVal2 = 0 + fVal1;
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if ((!std::isnan(fVal2))
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|| (static_cast<sal_uInt32>(0xbeef)
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!= static_cast<sal_uInt32>(
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reinterpret_cast<const sal_math_Double*>(&fVal2)->nan_parts.fraction_lo)))
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{
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m_aMessage = "Your platform does not support propagation of NaN payloads.";
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return;
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}
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reinterpret_cast<sal_math_Double*>(&fVal1)->nan_parts.fraction_lo = 0xdead;
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const double fVal3 = fVal1 + fVal2;
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// Result is one of the payloaded NaNs but the standard does not
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// specify which.
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if (0xbeef != reinterpret_cast<const sal_math_Double*>(&fVal3)->nan_parts.fraction_lo
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&& 0xdead != reinterpret_cast<const sal_math_Double*>(&fVal3)->nan_parts.fraction_lo)
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{
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m_aMessage = "Your platform does not support propagation of two combined NaN payloads.";
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return;
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}
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m_bSupported = true;
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}
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bool getIfSupported() { return m_bSupported; }
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std::string getMessage() { return m_aMessage; }
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};
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/* vim:set shiftwidth=4 softtabstop=4 expandtab cinoptions=b1,g0,N-s cinkeys+=0=break: */
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