table of contents
std::mul_sat(3) | C++ Standard Libary | std::mul_sat(3) |
NAME¶
std::mul_sat - std::mul_sat
Synopsis¶
Defined in header <numeric>
template< class T > (since C++26)
constexpr T mul_sat( T x, T y ) noexcept;
Computes the saturating multiplication x × 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,
* the largest or smallest value of type 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.
Parameters¶
x, y - integer values
Return value¶
Saturated x × y.
Exceptions¶
Throws no exceptions.
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
Possible implementation¶
See libstdc++ (gcc).
Example¶
Can be previewed on Compiler Explorer.
// Run this code
#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() {}
See also¶
add_sat saturating addition operation on two integers
(C++26) (function template)
sub_sat saturating subtraction operation on two integers
(C++26) (function template)
div_sat saturating division operation on two integers
(C++26) (function template)
saturate_cast returns an integer value clamped to the range of a another
integer
(C++26) type
(function template)
clamp clamps a value between a pair of boundary values
(C++17) (function template)
in_range checks if an integer value is in the range of a given integer type
(C++20) (function template)
min returns the smallest finite value of the given type
[static] (public static member function of
std::numeric_limits<T>)
max returns the largest finite value of the given type
[static] (public static member function of
std::numeric_limits<T>)
External links¶
1. A branch-free implementation of saturation arithmetic — Locklessinc.com, 2012
2024.06.10 | http://cppreference.com |