Hex Masking in PHP

Hi;

I've been banging my head against this wall for hours and am hoping someone can be of assistance. I am new to PHP, but an experienced programmer.

I need to take a hex string from a database and apply a Hex Mask

The problem I'm having is getting PHP to recognize that the value from the database is an actual hex value and return something meaningful:

Here's the code:

//$originalhex is the value found in the database. It is typically something like: 0xF1306D7100007132

$substring = substr($originalhex,$subL,$subR);   //I need to only mask certain digits...in this case I come up with 0xF13

$sdec = hexdec($substring);
$shex = dechex($sdec);

$maskedresult = $shex & 0x00F;               //This typically returns 0, but $shex returns F13 (I cannot add 0x to it without getting an error

//$maskedresult = 0xF13 & 0x00F;            //This line will give me the expected result

PHP:

Can anyone help?

Thanks!

 

Well, hex is still a number, isn't it? When you get $sdec, don't convert back. Use that to do bitwise AND with 0x00f, like this:

$substring = substr("0xF1306D7100007132",2,3);
$sdec = hexdec($substring);
$maskedresult = $sdec & 0x00F;

echo ($maskedresult);   // I got (int) 3

Code (markup):

- Rufas

 

/sigh

Forest for the trees.

Thanks man, that didn't even occur to me!