ParagonIE_Sodium_Core_BLAKE2b::rotr64

    public static function rotr64($x, $c)
    {
        if ($c >= 64) {
            $c %= 64;
        }
        if ($c >= 32) {
            /** @var int $tmp */
            $tmp = $x[0];
            $x[0] = $x[1];
            $x[1] = $tmp;
            $c -= 32;
        }
        if ($c === 0) {
            return $x;
        }

        $l0 = 0;
        $c = 64 - $c;

        if ($c < 32) {
            /** @var int $h0 */
            $h0 = ((int) ($x[0]) << $c) | (
                (
                    (int) ($x[1]) & ((1 << $c) - 1)
                        <<
                    (32 - $c)
                ) >> (32 - $c)
            );
            /** @var int $l0 */
            $l0 = (int) ($x[1]) << $c;
        } else {
            /** @var int $h0 */
            $h0 = (int) ($x[1]) << ($c - 32);
        }

        $h1 = 0;
        $c1 = 64 - $c;

        if ($c1 < 32) {
            /** @var int $h1 */
            $h1 = (int) ($x[0]) >> $c1;
            /** @var int $l1 */
            $l1 = ((int) ($x[1]) >> $c1) | ((int) ($x[0]) & ((1 << $c1) - 1)) << (32 - $c1);
        } else {
            /** @var int $l1 */
            $l1 = (int) ($x[0]) >> ($c1 - 32);
        }

        return self::new64($h0 | $h1, $l0 | $l1);
    }