バイトカッター

function byte_htm_cutter($str,$byte,$bf,$af){
	
	$byte = $byte * 2;
	
	$hex = bin2hex(mb_convert_encoding($str, $af, $bf));
	
	if($byte<strlen($hex)){
		
		$hex = mb_substr($hex,0,$byte,$af);
		
		$hex = mb_convert_encoding(pack("H*",$hex),$bf,$af);
		
		//最後の一文字削除
		$hex = mb_substr($hex,0,(strlen($hex)-1));
		
		//中途半端なタグ削除
		$hex = preg_replace('/\<[A-Za-z0-9\!\- \_\"\'\/\,\=\#]{0,50}$/','',$hex);
		
		return $hex;
		
	}else{
		
		return $str;
		
	}
	
}