解密经纬度数据(火星坐标)

//解密后的经纬度数据(火星坐标)

public function decode_poi($poi) {

    $settings = array(
        'digi' => 16,
        'add' => 10,
        'plus' => 7,
        'cha' => 36,
        'center' => array(
            'lat' => 34.957995,
            'lng' => 107.050781,
            'isDef' => TRUE
        )
    );
    $i = -1;
    $h = 0;
    $b = "";
    $j = strlen($poi);
    $g = ord($poi{$j - 1});
    $c = substr($poi, 0, $j - 1);
    $j--;

    for ($e = 0; $e < $j; $e++) {
        $d = base_convert($c{$e}, $settings['cha'], 10) - $settings['add'];
        if ($d >= $settings['add']) {
            $d = $d - $settings['plus'];
        }
        $b .= base_convert($d, 10, $settings['cha']);
        if ($d > $h) {
            $i = $e;
            $h = $d;
        }
    }
    $a = intval(substr($b, 0, $i), $settings['digi']);
    $f = intval(substr($b, $i + 1), $settings['digi']);
    $l = ($a + $f - intval($g)) / 2;
    $k = ($f - $l) / 100000;
    $l /= 100000;
    $lat = $k;
    $lon = $l;

    return array($lon, $lat);
}