Help me translate long value, expressed in hex, back in to a date/time

Question

I have a date value, which I\'m told is 8 bytes, a single \"long\" (aka int64) value, and converted to hex:

60f347d15798c901

How can I convert

Answer 1

(Thanks to thomasrutter's post, which gave me the Windows filetime epoch):

The given date appears to be a Windows 64-bit little-endian file date-time, 60 f3 47 d1 57 98 c9 01, which is equivalent to the quadword 01c99857d147f360 which as an integer is 128801567297500000

This is "the number of 100-nanosecond intervals that have elapsed since 12:00 midnight, January 1, 1601 A.D. (C.E.) Coordinated Universal Time (UTC)"

After conversion, it gives Thu, 26 February 2009 21:18:49 UTC

Sample code:

'0',   '1'=>'1',   '2'=>'2',   '3'=>'3',   '4'=>'4',
            '5'=>'5',   '6'=>'6',   '7'=>'7',   '8'=>'8',   '9'=>'9',
            'a'=>'a',   'b'=>'b',   'c'=>'c',   'd'=>'d',   'e'=>'e',   'f'=>'f',
            'A'=>'a',   'B'=>'b',   'C'=>'c',   'D'=>'d',   'E'=>'e',   'F'=>'f'
        );

        $t = '';
        $len = strlen($str);
        for ($i=0; $i<$len; ++$i) {
            $ch = $str[$i];
            if (isset($hex[$ch]))
                $t .= $hex[$ch];
        }

        return $t;
    }

    // swap little-endian to big-endian
    function flip_endian($str) {
        // make sure #digits is even
        if ( strlen($str) & 1 )
            $str = '0' . $str;

        $t = '';
        for ($i = strlen($str)-2; $i >= 0; $i-=2)
            $t .= substr($str, $i, 2);

        return $t;
    }

    // convert hex string to BC-int
    function hex_to_bcint($str) {
        $hex = array(
            '0'=>'0',   '1'=>'1',   '2'=>'2',   '3'=>'3',   '4'=>'4',
            '5'=>'5',   '6'=>'6',   '7'=>'7',   '8'=>'8',   '9'=>'9',
            'a'=>'10',  'b'=>'11',  'c'=>'12',  'd'=>'13',  'e'=>'14',  'f'=>'15',
            'A'=>'10',  'B'=>'11',  'C'=>'12',  'D'=>'13',  'E'=>'14',  'F'=>'15'
        );

        $bci = '0';
        $len = strlen($str);
        for ($i=0; $i<$len; ++$i) {
            $bci = bcmul($bci, '16');

            $ch = $str[$i];
            if (isset($hex[$ch]))
                $bci = bcadd($bci, $hex[$ch]);
        }

        return $bci;
    }

    // WARNING! range clipping
    //   Windows date time has range from 29000 BC to 29000 AD
    //   Unix time only has range from 1901 AD to 2038 AD
    // WARNING! loss of accuracy
    //   Windows date time has accuracy to 0.0000001s
    //   Unix time only has accuracy to 1.0s
    function win64_to_unix($bci) {
        // Unix epoch as a Windows file date-time value
        $magicnum = '116444735995904000';

        $t = bcsub($bci, $magicnum);    // Cast to Unix epoch
        $t = bcdiv($t, '10000000', 0);  // Convert from ticks to seconds

        return $t;
    }

// get input
$dtval = isset($_GET["dt"]) ? strval($_GET["dt"]) : "0";
$dtval = hexstring($dtval);         // strip non-hex chars

// convert to quadword
$dtval = substr($dtval, 0, 16);     // clip overlength string
$dtval = str_pad($dtval, 16, '0');  // pad underlength string
$quad = flip_endian($dtval);

// convert to int
$win64_datetime = hex_to_bcint($quad);

// convert to Unix timestamp value
$unix_datetime = win64_to_unix($win64_datetime);

?>





    

        Datetime value: 
        
    
    

    Result:
        Quad: 

        Int: 

        Unix timestamp: 

        Date: