template< class T >
constexpr T mul_sat( T x, T y ) noexcept;
Computes the saturating multiplication x à y. This operation (unlike built-in arithmetic operations on integers) behaves as-if it is a mathematical operation with an infinite range. Let q
denote the result of such operation. Returns:
q
, if q
is representable as a value of type T
. Otherwise,T
, whichever is closer to the q
.This overload participates in overload resolution only if T
is an integer type, that is: signed char, short, int, long, long long, an extended signed integer type, or an unsigned version of such types. In particular, T
must not be (possibly cv-qualified) bool, char, wchar_t, char8_t, char16_t, and char32_t, as these types are not intended for arithmetic.
Saturated x à y.
[edit] NotesUnlike the built-in arithmetic operators on integers, the integral promotion does not apply to the x and y arguments.
If two arguments of different type are passed, the call fails to compile, i.e. the behavior relative to template argument deduction is the same as for std::min or std::max.
Most modern hardware architectures have efficient support for saturation arithmetic on SIMD vectors, including SSE2 for x86 and NEON for ARM.
[edit] Possible implementationSee libstdc++ (gcc).
[edit] ExampleCan be previewed on Compiler Explorer.
#include <climits> #include <numeric> static_assert ("" && (std::mul_sat<int>(2, 3) == 6) // not saturated && (std::mul_sat<int>(INT_MAX / 2, 3) == INT_MAX) // saturated && (std::mul_sat<int>(-2, 3) == -6) // not saturated && (std::mul_sat<int>(INT_MIN / -2, -3) == INT_MIN) // saturated && (std::mul_sat<unsigned>(2, 3) == 6) // not saturated && (std::mul_sat<unsigned>(UINT_MAX / 2, 3) == UINT_MAX) // saturated ); int main() {}[edit] See also saturating addition operation on two integers
std::numeric_limits<T>
) [edit] returns the largest finite value of the given type
std::numeric_limits<T>
) [edit] [edit] External links
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