strips control characters from feed content

gistfile1.txt

// non-prefixed version submited to core as patch
function tc_strip_for_xml( $string ) {
    // Store the site charset as a static to avoid multiple calls to get_option()
    static $is_utf8;
    if ( ! isset( $is_utf8 ) ) {
        $is_utf8 = in_array( get_option( 'blog_charset' ), array( 'utf8', 'utf-8', 'UTF8', 'UTF-8' ) );
    }
    if ( ! $is_utf8 ) {
        return $string;
    }

    return preg_replace( '/[^\x{0009}\x{000a}\x{000d}\x{0020}-\x{D7FF}\x{E000}-\x{FFFD}]+/u', ' ', $string );
}

function tc_the_content_strip_for_xml( $content ) {
  if ( is_feed() )
		$content = tc_strip_for_xml( $content );

	return $content;
}
add_filter( 'the_content', 'tc_the_content_strip_for_xml' );