std::saturating_div
| Defined in header <numeric>
|
||
template< class T >
constexpr T saturating_div( T x, T y ) noexcept;
|
(since C++26) | |
Computes the saturating division x / y. If T is a signed integer type, x is the smallest (most negative) value of T, and y == -1, returns the greatest value of T; otherwise, returns x / y.
y must not be 0, otherwise the behavior is undefined. The function call is not a core constant expression if undefined behavior happens.
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.
Parameters
| x, y | - | integer values |
Return value
Saturated x / y.
Notes
Unlike 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.
| Feature-test macro | Value | Std | Feature |
|---|---|---|---|
__cpp_lib_saturation_arithmetic |
202311L |
(C++26) | Saturation arithmetic |
202603L |
(C++26) | Renaming saturation arithmetic functions |
Possible implementation
namespace detail {
template<class T>
concept standard_or_extended_integral =
std::is_integral_v<T> &&
!std::is_same_v<std::remove_cv_t<T>, bool> &&
!std::is_same_v<std::remove_cv_t<T>, char> &&
!std::is_same_v<std::remove_cv_t<T>, char8_t> &&
!std::is_same_v<std::remove_cv_t<T>, char16_t> &&
!std::is_same_v<std::remove_cv_t<T>, char32_t> &&
!std::is_same_v<std::remove_cv_t<T>, wchar_t>;
} // namespace detail
template<detail::standard_or_extended_integral T>
constexpr T saturating_div( T x, T y ) noexcept
{
if constexpr (std::is_signed_v<T>)
if (x == std::numeric_limits<T>::min() && y == -1)
return std::numeric_limits<T>::max();
return x / y;
}
|
Example
Can be previewed on Compiler Explorer.
#include <climits>
#include <numeric>
static_assert
(""
&& (std::saturating_div<int>(6, 3) == 2) // not saturated
&& (std::saturating_div<int>(INT_MIN, -1) == INT_MAX) // saturated
&& (std::saturating_div<unsigned>(6, 3) == 2) // not saturated
);
int main() {}
See also
(C++26) |
saturating addition operation on two integers (function template) |
(C++26) |
saturating subtraction operation on two integers (function template) |
(C++26) |
saturating multiplication operation on two integers (function template) |
(C++26) |
returns an integer value clamped to the range of another integer type (function template) |
(C++17) |
clamps a value between a pair of boundary values (function template) |
(C++20) |
checks if an integer value is in the range of a given integer type (function template) |
[static] |
returns the smallest finite value of the given non-floating-point type, or the smallest positive normal value of the given floating-point type (public static member function of std::numeric_limits<T>)
|
[static] |
returns the largest finite value of the given type (public static member function of std::numeric_limits<T>)
|
External links
| 1. | A branch-free implementation of saturation arithmetic — Locklessinc.com, 2012 |
