I am trying to convert a timestamp of the format `2009-09-12 20:57:19` and turn it into something like `3 minutes ago` with PHP.

I found a useful script to do this, but I think it's looking for a different format to be used as the time variable. The script I'm wanting to modify to work with this format is:

```
function _ago($tm,$rcs = 0) {
    $cur_tm = time(); 
    $dif = $cur_tm-$tm;
    $pds = array('second','minute','hour','day','week','month','year','decade');
    $lngh = array(1,60,3600,86400,604800,2630880,31570560,315705600);

    for($v = sizeof($lngh)-1; ($v >= 0)&&(($no = $dif/$lngh[$v])<=1); $v--); if($v < 0) $v = 0; $_tm = $cur_tm-($dif%$lngh[$v]);
        $no = floor($no);
        if($no <> 1)
            $pds[$v] .='s';
        $x = sprintf("%d %s ",$no,$pds[$v]);
        if(($rcs == 1)&&($v >= 1)&&(($cur_tm-$_tm) > 0))
            $x .= time_ago($_tm);
        return $x;
    }

```

I think on those first few lines the script is trying to do something that looks like this (different date format math):

```
$dif = 1252809479 - 2009-09-12 20:57:19;

```

How would I go about converting my timestamp into that (unix?) format?