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Add helper function for unsigned saturating add

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This commit is contained in:
Jonathan G Rennison
2024-03-11 20:40:27 +00:00
parent fe730bce31
commit cc2521ddf5
2 changed files with 30 additions and 0 deletions
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20
src/core/math_func.hpp
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@@ -414,6 +414,26 @@ constexpr uint64_t PowerOfTen(int power)
return result;
}
/**
* Unsigned saturating add.
*/
template<typename T, std::enable_if_t<std::is_unsigned_v<T>, int> = 0>
constexpr inline T SaturatingAdd(T a, T b)
{
#ifdef WITH_OVERFLOW_BUILTINS
T c;
if (unlikely(__builtin_add_overflow(a, b, &c))) {
return std::numeric_limits<T>::max();
}
return c;
#else
T c = a + b;
if (c < a) return std::numeric_limits<T>::max();
return c;
#endif
}
uint32_t IntSqrt(uint32_t num);
uint32_t IntSqrt64(uint64_t num);
uint32_t IntCbrt(uint64_t num);

10
src/tests/math_func.cpp
View File

@@ -95,3 +95,13 @@ TEST_CASE("SoftClamp")
CHECK(1250 * million == SoftClamp(0, 1500 * million, 1000 * million));
CHECK(0 == SoftClamp(0, 1500 * million, -1500 * million));
}
TEST_CASE("SaturatingAdd")
{
CHECK(SaturatingAdd<uint8_t>(2, 3) == 5);
CHECK(SaturatingAdd<uint8_t>(200, 200) == 255);
CHECK(SaturatingAdd<uint8_t>(255, 255) == 255);
CHECK(SaturatingAdd<uint8_t>(1, 255) == 255);
CHECK(SaturatingAdd<uint8_t>(255, 1) == 255);
CHECK(SaturatingAdd<uint8_t>(0, 254) == 254);
}