<xstd/ints/bit/rotl.hpp>

This page also specifies <xstd/ints/bit/rotr.hpp>, whose functions share this text.

xstd::rotl, xstd::rotr

// (1)
template<class T>
  constexpr auto rotl(T x, int s) noexcept(see below) -> T;

// (2)
template<class T>
  constexpr auto rotr(T x, int s) noexcept(see below) -> T;

Rotate the bits of an unsigned integer, for every type the standard functions take and every unsigned_integer.

1. rotl rotates to the left.
2. rotr rotates to the right.

In the following, let N be numeric_limits<T>::digits and r be s % N.

Parameters

Parameter	Meaning
x	the value to rotate
s	the count to rotate by, which may be negative

Constraints: For each function f, std::f(x, s) is well-formed, or T models unsigned_integer.

Return value

Where std::f(x, s) is well-formed, each returns std::f(x, s).

1. Returns: x if r is 0; (x << r) | (x >> (N - r)) if r is positive; rotr(x, -r) if r is negative. This is [bit.rotate]'s element.
2. Returns: x if r is 0; (x >> r) | (x << (N - r)) if r is positive; rotl(x, -r) if r is negative. This is [bit.rotate]'s element.

Exceptions

The exception specification is true for the forwarding overload, and otherwise nothrow_const_operators<T>.

Notes

• Every int count is in the domain, INT_MIN and INT_MAX included, and turning one way and then the other by the same count is the identity.
• A call is a constant expression.

See also

Entity	Relation
shl, shr	shift rather than rotate
unsigned_integer	what the block template takes
std::rotl	the standard function (1) forwards to
std::rotr	the standard function (2) forwards to