PHP function required to convert hex to lat & long

I have a question regarding lattitude and longitude encoding, the answer to which my brain refuses to produce.

I need to write a php function that takes the value '1446041F' and '447D1100' (Lat & Lng) does some processing (the bit I cannot fathom) and outputs '52.062297' and '0.191030'.

I am told the Lat & Lng are encoded to 4 bytes from a signed degrees, minutes and decimal minutes with a format as follows;

Latitude: SDDMM.MMMMM where 0≤DD≤90, S = [+|-], 0≤M≤9
Longitude: SDDDMM.MMMMM where 0≤DDD≤180, S = [+|-], 0≤M≤9

See that last bit, I've searched many sites but I still have no idea what that all means.

I'm aware this is a massive shot in the dark and it may be so si开发者_运维技巧mple that I am rightfully told to sit in the corner wearing the dunce hat but I am running low on hair to pull out!

Any advice is much appreciated.

Thanks, Matthew

The examples you gave, 1446041F and 447D1100 are probably 32-bit signed integers in little-endian byte order. They are to be read as follows:

1446041F -> 0x1F044614 -> 520373780
447D1100 -> 0x00117D44 -> 001146180

They can be interpreted in degrees and minutes like this:

520373780 -> 52 degrees, 03.73780 minutes
1146480 -> 0 degrees, 11.46480 minutes

The following function will convert the hex values you specified to degrees. I assume the values are integers like 0x447D1100 and the like. If I assume wrong and the input values are actually strings, let me know. I put this function into the public domain.

function hextolatlon($hex){
  // Assume hex is a value like 0x1446041F or 0x447D1100
  // Convert to a signed integer
  $h=$hex&0xFF;
  $h=($h<<8)|(($hex>>8)&0xFF);
  $h=($h<<8)|(($hex>>16)&0xFF);
  $h=($h<<8)|(($hex>>24)&0xFF);
  $negative=($h>>31)!=0; // Get the sign
  if($negative){
   $h=~$h;
   $h=$h&0x7FFFFFFF;
   $h++;
  }
  // Convert to degrees and minutes
  $degrees=floor($h/10000000);
  $minutes=$h%10000000;
  // Convert to full degrees
  $degrees+=($minutes/100000.0) / 60.0;
  if($negative)$degrees=-$degrees;
  return $degrees;
}

Here's the PHP (the verbosity is for clarity):

function llconv($hex) {
    // Pack hex string:
    $bin = pack('H*', $hex);

    // Unpack into integer (returns array):
    $unpacked = unpack('V', $bin);

    // Get first (and only) element:
    $int = array_shift($unpacked);

    // Decimalize minutes:
    $degmin = $int / 100000;

    // Get degrees:
    $deg = (int)($degmin/100);

    // Get minutes:
    $min = $degmin - $deg*100;

    // Return degress:
    return round($deg + ($min/60), 6);
}

$long = '1446041F';
$lat = '447D1100';

$iLong = llconv($long);
$iLat = llconv($lat);

print "Out: $iLong x $iLat\n";