phpseclib\Crypt\RC2::_decryptBlock PHP Method

    function _decryptBlock($in)
    {
        list($r0, $r1, $r2, $r3) = array_values(unpack('v*', $in));
        $keys = $this->keys;
        $limit = 44;
        $actions = array($limit => 20, 20 => 0);
        $j = 64;
        for (;;) {
            // R-mixing round.
            $r3 = ($r3 | $r3 << 16) >> 5;
            $r3 = $r3 - $keys[--$j] - (($r0 ^ $r1) & $r2 ^ $r0) & 0xffff;
            $r2 = ($r2 | $r2 << 16) >> 3;
            $r2 = $r2 - $keys[--$j] - (($r3 ^ $r0) & $r1 ^ $r3) & 0xffff;
            $r1 = ($r1 | $r1 << 16) >> 2;
            $r1 = $r1 - $keys[--$j] - (($r2 ^ $r3) & $r0 ^ $r2) & 0xffff;
            $r0 = ($r0 | $r0 << 16) >> 1;
            $r0 = $r0 - $keys[--$j] - (($r1 ^ $r2) & $r3 ^ $r1) & 0xffff;
            if ($j === $limit) {
                if ($limit === 0) {
                    break;
                }
                // R-mashing round.
                $r3 = $r3 - $keys[$r2 & 0x3f] & 0xffff;
                $r2 = $r2 - $keys[$r1 & 0x3f] & 0xffff;
                $r1 = $r1 - $keys[$r0 & 0x3f] & 0xffff;
                $r0 = $r0 - $keys[$r3 & 0x3f] & 0xffff;
                $limit = $actions[$limit];
            }
        }
        return pack('vvvv', $r0, $r1, $r2, $r3);
    }