Bitwise Unsigned Right Shift

[rallan]

Is there any PHP equivelant to the Flash/Java >>> operator?

[dagon]

php does not have unsigned integers, as to the solution -um pass.

[rallan]

The code I was trying to port to PHP:

while (_local1 != 0) {
                        _local2 = _local2 - ((((_local3 << 4) ^ (_local3 >>> 5)) + _local3) ^ (_local1 + _arg5[(_local1 >>> 11) & 3]));
                        _local1 = _local1 - _local6;
                        _local3 = _local3 - ((((_local2 << 4) ^ (_local2 >>> 5)) + _local2) ^ (_local1 + _arg5[_local1 & 3]));
                    }

That code is the XTEA (eXtended Tiny Encryption Algorithm).

Is there a way of replicationg this in PHP. The bitwise >> operator produces 0(every time)

[dagon]

PHP implementation of XTEA

[rallan]

Sorry, forgot to mark topic as solved!.

I found

function SHR($x, $n)    // x >> n
{
    $mask = 0x40000000;

if ($x < 0)
{
    $x &= 0x7FFFFFFF;
    $mask = $mask >> ($n-1);
    return ($x >> $n) | $mask;
}

return (int)$x >> (int)$n;
}

(Not Mine)

[John_Doe2]

Rallan,

The code you've got is ALMOST perfect...
But it always fail when $x < 0.

After HOURS studying it and testing it and comparing it to the real results coming from FLASH CS3 (AS3), I did it. I fixed the code!

I know it can (and must) be optimized!
But I can't handle it anymore, at least now. Sooo tired!

Here is the code:

function SHR($x, $n){
    $mask = 0x40000000;
    if ($x < 0){
        $x &= 0x7FFFFFFF;
        $mask = $mask >> ($n-1);
        $ret = ($x >> $n) | $mask;
	// My fix comes here (setting the bit '32' as positive):
	$ret    = str_pad(decbin($ret),    32, '0', STR_PAD_LEFT);
	$ret[0] = '1';
	$ret    = bindec($ret);
    }
    else{
        $ret = (int)$x >> (int)$n;
    }
    return $ret;
}

I registered to this forum ONLY to post the solution.
I hope I can help other people having the same headache as me.

Anyway, thanks Rallan! Without you, I would be completely lost by now.

Good luck to everyone.