perl循环匹配，并且模式中不包含某字符串

#header-search .search-submit { float: left; width: 80px; height: 30px; margin: 0; padding: 0; border: 0; background: url(../img/header-submit.png) no-repeat; cursor: pointer;} #footer { width: 100%; padding-top: 20px; background: #fff url('../img/footer-spl.gif') repeat-x center top;}

单行有多个url，perl进行循环模式匹配，并且不包含“url（”字符串?? ((?!url).)*

while(my $line = <CSS> ) {
        while($line =~ m/url(["|']?(((?!url().)*.(?:png|gif|jpg|jpeg|map))["|']?)/gi) {
                print $1,"n";
        }
}