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https://github.com/libretro/dolphin
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0a3631cc76
Type punning via unions in C++ invokes undefined behavior. Instead, leverage BitCast, our variant of C++2a's std::bit_cast
68 lines
2.6 KiB
C++
68 lines
2.6 KiB
C++
// Copyright 2018 Dolphin Emulator Project
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// Licensed under GPLv2+
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// Refer to the license.txt file included.
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#include <limits>
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#include <random>
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#include <gtest/gtest.h>
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#include "Common/BitUtils.h"
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#include "Common/FloatUtils.h"
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TEST(FloatUtils, IsQNAN)
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{
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EXPECT_TRUE(Common::IsQNAN(std::numeric_limits<double>::quiet_NaN()));
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EXPECT_FALSE(Common::IsQNAN(Common::SNANConstant<double>()));
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}
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TEST(FloatUtils, IsSNAN)
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{
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EXPECT_FALSE(Common::IsSNAN(std::numeric_limits<double>::quiet_NaN()));
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EXPECT_TRUE(Common::IsSNAN(Common::SNANConstant<double>()));
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}
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TEST(FloatUtils, FlushToZero)
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{
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// To test the software implementation we need to make sure FTZ and DAZ are disabled.
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// Using volatile here to ensure the compiler doesn't constant-fold it,
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// we want the multiplication to occur at test runtime.
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volatile float s = std::numeric_limits<float>::denorm_min();
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volatile double d = std::numeric_limits<double>::denorm_min();
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// Casting away the volatile attribute is required in order for msvc to resolve this to the
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// correct instance of the comparison function.
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EXPECT_LT(0.f, (float)(s * 2));
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EXPECT_LT(0.0, (double)(d * 2));
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EXPECT_EQ(+0.0, Common::FlushToZero(+std::numeric_limits<double>::denorm_min()));
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EXPECT_EQ(-0.0, Common::FlushToZero(-std::numeric_limits<double>::denorm_min()));
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EXPECT_EQ(+0.0, Common::FlushToZero(+std::numeric_limits<double>::min() / 2));
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EXPECT_EQ(-0.0, Common::FlushToZero(-std::numeric_limits<double>::min() / 2));
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EXPECT_EQ(std::numeric_limits<double>::min(),
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Common::FlushToZero(std::numeric_limits<double>::min()));
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EXPECT_EQ(std::numeric_limits<double>::max(),
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Common::FlushToZero(std::numeric_limits<double>::max()));
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EXPECT_EQ(+std::numeric_limits<double>::infinity(),
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Common::FlushToZero(+std::numeric_limits<double>::infinity()));
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EXPECT_EQ(-std::numeric_limits<double>::infinity(),
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Common::FlushToZero(-std::numeric_limits<double>::infinity()));
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// Test all subnormals as well as an equally large set of random normal floats.
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std::default_random_engine engine(0);
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std::uniform_int_distribution<u32> dist(0x00800000u, 0x7fffffffu);
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for (u32 i = 0; i <= 0x007fffffu; ++i)
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{
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u32 i_tmp = i;
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EXPECT_EQ(+0.f, Common::FlushToZero(Common::BitCast<float>(i_tmp)));
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i_tmp |= 0x80000000u;
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EXPECT_EQ(-0.f, Common::FlushToZero(Common::BitCast<float>(i_tmp)));
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i_tmp = dist(engine);
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EXPECT_EQ(i_tmp, Common::BitCast<u32>(Common::FlushToZero(Common::BitCast<float>(i_tmp))));
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i_tmp |= 0x80000000u;
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EXPECT_EQ(i_tmp, Common::BitCast<u32>(Common::FlushToZero(Common::BitCast<float>(i_tmp))));
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}
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}
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