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MathUtil: Add SaturatingCast to cast floats more safely

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This commit is contained in:
Léo Lam
2021-01-28 12:45:50 +01:00
parent ac250f7c20
commit 48712168b8
2 changed files with 85 additions and 0 deletions
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42
Source/UnitTests/Common/MathUtilTest.cpp
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@ -26,3 +26,45 @@ TEST(MathUtil, NextPowerOf2)
EXPECT_EQ(8U, MathUtil::NextPowerOf2(6));
EXPECT_EQ(0x40000000U, MathUtil::NextPowerOf2(0x23456789));
}
TEST(MathUtil, SaturatingCast)
{
// Cast from an integer type to a smaller type
EXPECT_EQ(255u, (MathUtil::SaturatingCast<u8, int>(1000)));
EXPECT_EQ(255u, (MathUtil::SaturatingCast<u8, u16>(1000u)));
EXPECT_EQ(255u, (MathUtil::SaturatingCast<u8, std::size_t>(1000)));
// Cast from a signed integer type
EXPECT_EQ(0u, (MathUtil::SaturatingCast<u8, int>(-1)));
EXPECT_EQ(0u, (MathUtil::SaturatingCast<u8, int>(-1000)));
EXPECT_EQ(0u, (MathUtil::SaturatingCast<u32, int>(-1)));
EXPECT_EQ(-1000, (MathUtil::SaturatingCast<s16, int>(-1000)));
EXPECT_EQ(-1000, (MathUtil::SaturatingCast<int, int>(-1000)));
EXPECT_EQ(-1000, (MathUtil::SaturatingCast<s64, int>(-1000)));
// Cast from an unsigned integer type to a smaller integer type
EXPECT_EQ(0x7fff, (MathUtil::SaturatingCast<s16, u32>(0xffffffffu)));
EXPECT_EQ(0x7fffffff, (MathUtil::SaturatingCast<int, u32>(0xffffffffu)));
// Cast from a floating point type to an integer type
EXPECT_EQ(255u, MathUtil::SaturatingCast<u8>(1234.0));
EXPECT_EQ(0u, MathUtil::SaturatingCast<u8>(-1234.0));
EXPECT_EQ(127, MathUtil::SaturatingCast<s8>(5678.0));
EXPECT_EQ(-128, MathUtil::SaturatingCast<s8>(-5678.0));
EXPECT_EQ(65535u, MathUtil::SaturatingCast<u16>(999999.0));
// Negative zero
EXPECT_EQ(0u, MathUtil::SaturatingCast<u8>(0.0));
EXPECT_EQ(0u, MathUtil::SaturatingCast<u8>(-0.0));
EXPECT_EQ(0, MathUtil::SaturatingCast<s8>(0.0));
EXPECT_EQ(0, MathUtil::SaturatingCast<s8>(-0.0));
// Edge cases
EXPECT_EQ(std::numeric_limits<s32>::max(),
MathUtil::SaturatingCast<s32>(std::numeric_limits<float>::infinity()));
EXPECT_EQ(std::numeric_limits<s32>::min(),
MathUtil::SaturatingCast<s32>(-std::numeric_limits<float>::infinity()));
// 16777217 = 2^24 + 1 is the first integer that cannot be represented correctly with a f32.
EXPECT_EQ(16777216, MathUtil::SaturatingCast<s32>(float(16777216)));
EXPECT_EQ(16777216, MathUtil::SaturatingCast<s32>(float(16777217)));
}