Here is a solution with less code:
Changes in read, and no use of array_reverse:
function language_user_setting( $hls )
{
$browser_langs=array();
$t_hls = transform_language_arr($hls);
$useUsort = 1;
$qualityArr = array();
// Check if we have $_SERVER['HTTP_ACCEPT_LANGUAGE'] set and
// it no longer breaks if you only have one language set
if (isset($_SERVER['HTTP_ACCEPT_LANGUAGE'])) {
$browser_accept = explode(",", $_SERVER['HTTP_ACCEPT_LANGUAGE']);
// Go through all language preference specs
for ($i = 0; $i < count($browser_accept); $i++) {
// The language part is either a code or a code with a quality
// We cannot do anything with a * code, so it is skipped
// If the quality is missing, it is assumed to be 1 according to the RFC
if (preg_match("!([a-z-]+)(;q=([0-9\\.]+))?!", trim($browser_accept[$i]), $found)) {
$quality = (isset($found[3]) ? (float) $found[3] : 1.0);
$browser_langs[] = array($found[1], $quality);
if ($useUsort == 1 && array_search($quality, $qualityArr) === false){
$qualityArr[] = $quality;
} else if ($useUsort == 1){
$useUsort = 0;
}
}
unset($found);
}
}
// Order the codes by quality
if ($useUsort == 1){
usort($browser_langs, "language_accept_order");
}