3 * ${class}${atomicname}() - atomic compare and exchange with ${desc_order} ordering
4 * @v: pointer to ${atomic}_t
5 * @old: ${int} value to compare with
6 * @new: ${int} value to assign
8 * If (@v == @old), atomically updates @v to @new with ${desc_order} ordering.
9 * Otherwise, @v is not modified and relaxed ordering is provided.
13 * Return: The original value of @v.