File Coverage

blib/lib/Geo/Approx.pm

Criterion	Covered	Total	%
statement	56	57	98.2
branch	5	6	83.3
condition	3	9	33.3
subroutine	15	15	100.0
pod	2	3	66.6
total	81	90	90.0

package Geo::Approx;
use strict;
use Carp;
use Math::Trig;
use vars qw ( $VERSION );
$^W = 1;

$VERSION = 0.8;

my %mask;
BEGIN
{
    for(my $i=0;$i<=32;$i++){
	$mask{$i} = pack("B32",('0'x(32-$i) . '1'x$i));
    }
}

sub new
{
    my ($caller,$precision) = @_;
    my $class = ref($caller) || $caller;
    if(defined $precision){
	unless(($precision =~ /^(\d+)$/)&&($1>=0)&&($1<=32))
	{
	    croak("optional argument to Geo::Aprox constructor must be a precision between zero and 32");
	}
    } else {
	$precision = 32;
    }
    bless \$precision,$class;
}

sub latlon2int
{
    my $prec = ${$_[0]};
    my $result = _intint2int(_lat2int($_[1]),_lon2int($_[2]));
    $result = _setPrecision($prec,$result);
    return $result;
}

sub int2latlon
{
    my $mask = \$_[0];
    my ($lat_int,$lon_int) = _int2intint($_[1]);
    my $lat = _int2lat($lat_int);
    my $lon = _int2lon($lon_int);
    return ($lat,$lon);
}

sub _setPrecision
{
    my ($prec,$num) = @_;
    return unpack("N",pack("N",$num)&$mask{$prec});
}

sub _int2lat # 0 to 65535
{
    return rad2deg(asin(($_[0]+0.5)/32768-1.0));
}

sub _lat2int # -90 to 90 inclusive
{
    my $result = int((sin(deg2rad($_[0]))+1.0)*32768);
    $result = 65535 if ($result==65536); # special case for lat==90.000
    return int($result);
} # 0 to 65535

sub _lon2int # -180 to 180 inclusive
{
    my $result = int(($_[0]/360 + 0.5)*65536);
    $result %= 65536; # wrap-around
    return $result;
} # 0 to 65535 inclusive

sub _int2lon # 0 to 65535 inclusive
{
    return ($_[0]/65536 - 0.5)*360;
} # -180 to <180

sub _intint2int # two 16-bit numbers
{
    my $bina = substr(unpack("B32",pack("N",$_[0])),-16);
    my $binb = substr(unpack("B32",pack("N",$_[1])),-16);
    my $bbiinnab;
    for(my $i=0;$i<16;$i++){
	$bbiinnab .= substr($bina,$i,1);
	$bbiinnab .= substr($binb,$i,1);
    }
    my $dec = unpack("V",pack("B32",$bbiinnab));
    return $dec;
} # one 32-bit number

sub _int2intint # one 32-bit number
{
    my $bbiinnab = substr(unpack("B32",pack("V",$_[0])),-32);
    my ($bina,$binb) = ('0000000000000000','0000000000000000');
    for(my $i=0;$i<32;$i+=2){
	$bina .= substr($bbiinnab,$i,1);
	$binb .= substr($bbiinnab,$i+1,1);
    }
    my $deca = unpack("N",pack("B32",$bina));
    my $decb = unpack("N",pack("B32",$binb));
    return ($deca,$decb);
} # two 16-bit numbers

1;

__END__