#!/usr/bin/perl 
        # 
        # This is a derivative of a script by mcr@sandelman.ca. 
        #  http://www.sandelman.ottawa.on.ca/SSW/ietf/geo-pi/  
        # 
        # The primary modification was to adjust for the change 
        # to sections and origin. This version also adds an 
        # option for decimal degree input format. 
        # 
        # alh-ietf@tndh.net  2002/12/31 
        # 
         
        print "Please select format  1) dd.mm.ss  or  2) dd.ddddd: "; 
        chop($fmt=<STDIN>); 
         
        print "Use minus (-) for south or west values. \n"; 
        print "Please enter your lattitude: "; 
        chop($lat=<STDIN>); 
         
        print "Please enter your longitude: "; 
        chop($long=<STDIN>); 
         
        if($fmt == 1) { 
           ($longdeg, $longmin, $longsec) = split(/ /, $long); 
           ($latdeg, $latmin, $latsec) = split(/ /, $lat); 
         
           if($longdeg < 0) { 
             $longdeg = 360 + $longdeg; 
           } 
           if($latdeg < 0) { 
              $latdeg = -$latdeg; 
              $south = 1; 
           } 
           $wgs84long = $longdeg + ($longmin / 60) + ($longsec / 360); 
           $wgs84lat  = $latdeg +  ($latmin / 60)  + ($latsec / 360); 
         
           if($south == 1) { 
              $wgs84lat = -$wgs84lat; 
           } 
        } else { 
           if ($long < 0) { 
              $wgs84long = 360 + $long; 
           } else { 
           $wgs84long = $long; 
           } 
        } 
        $wgs84lat = 90 + $lat; 
         
        # Origin is now south pole @ 0 degrees 
         
        if ($wgs84lat >= 30) { 
           if ($wgs84lat < 150) { 
              $seclat = $wgs84lat - 30; 
              if ($wgs84long >= 90) { 
                 if ($wgs84long < 210) { 
                    $section = 0; 
                    $seclong = $wgs84long - 90; 
                 } elsif ($wgs84long < 330) { 
                    $section = 1; 
                    $seclong = $wgs84long - 210; 
                 } else { 
                    $section = 2; 
                    $seclong = $wgs84long - 330; 
                 } 
              } else { 
                 $section = 2; 
                 $seclong = $wgs84long + 30; 
              } 
           } else { 
              $section = 7; 
              $seclat = $wgs84lat - 150; 
              $seclong = $wgs84long - 90; 
           } 
        } else { 
           $section = 6; 
           $seclat = $wgs84lat; 
           $seclong = $wgs84long - 90; 
        } 
        if ($seclong < 0) { 
           $seclong = 360 + $seclong; 
        } 
         
        # Origin is now normalized to section 
        print ("Sec Lat: $seclat \n"); 
        print ("Sec Long: $seclong \n"); 
         
        if($section < 3) { 
           $seclong = int($seclong / 0.000057220458984375); 
           $seclat  = int($seclat  / 0.000057220458984375); 
        } else { 
           $seclong = int($seclong / 0.00017166137695312500); 
           $seclat  = int($seclat  / 0.00017166137695312500); 
        } 
         
        # convert to binary 
        @lat  = &convert_to_binary($seclat); 
        @long = &convert_to_binary($seclong); 
        @secbin = &convert_to_binary($section); 
         
        print "Raw sec:",join('', @secbin),"\n"; 
        print "Raw lat: ",join('', @lat),"\n"; 
        print "Raw long:",join('', @long),"\n"; 
         
        # clean off excess leading 0's 
        foreach $i (1..11) { 
          shift(@lat); 
          shift(@long); 
        } 
        foreach $i (1..29) { 
          shift(@secbin); 
        } 
         
        # interleave bits 
        @geopi=(); 
           if ($section > 3) { 
              foreach $i (1..3) { 
                 $secid = shift(@secbin); 
                 push(@geopi, $secid); 
              } 
           } else { 
             shift(@secbin); 
              foreach $i (1..2) { 
                 $secid = shift(@secbin); 
                 push(@geopi, $secid); 
              } 
           } 
           my($o,$a); 
           foreach $i (1..21) { 
              $o = shift(@long); 
              $a = shift(@lat); 
              if ($section > 3 && $i == 1) { 
        #  skip this bit in polar sections 
              } else { 
              push(@geopi, $a); 
              } 
              push(@geopi, $o); 
           } 
         
        print "Digits ",join('', @geopi),"\n"; 
        print "Lat: $lat Long: $long  -> x"; 
         
        foreach $i (0..10) { 
          @nibble = @geopi[($i*4)..($i*4+3)]; 
          $nibble = $nibble[0]*8 + $nibble[1]*4 + $nibble[2]*2 + $nibble[3]; 
          print sprintf("%x", $nibble); 
          if($i==2 || $i==6) { 
            print ":"; 
          } 
        } 
        print "\n"; 
         
        exit; 
         
        sub convert_to_binary { 
          local($num)=@_; 
          local($i, @digits); 
         
          @digits=(); 
          foreach $i (1..32) { 
            if($num & 1) { 
              unshift(@digits, 1); 
            } else { 
              unshift(@digits, 0); 
            } 
            $num = $num >> 1; 
          } 
          return @digits; 
        }