var maxSize=116; //Tamanho máximo de um torpedo

function updateMessageCounter() {

 var oper = document.torpedo.operadora.value;
 var numCaracteres;
 if(oper=="OI")
 {
    maxSize=101;
    numCaracteres = maxSize -(document.torpedo.sms.value.length )-(document.torpedo.nomer.value.length )-(document.torpedo.dddr.value.length )-(document.torpedo.numeror.value.length );
 }
 else if (oper == "CLARO")
 {
   maxSize = 129; // Tamanho total
   numCaracteres = maxSize -(document.torpedo.sms.value.length )-(document.torpedo.nomer.value.length )-(document.torpedo.dddr.value.length )-(document.torpedo.numeror.value.length );
 }
 else
 {
    maxSize=110;
    numCaracteres = maxSize -(document.torpedo.sms.value.length );
 }
 
 if(numCaracteres<0){
    document.torpedo.sms.value = document.torpedo.sms.value.substring(0,document.torpedo.sms.value.length + numCaracteres);
    numCaracteres=0;
     alert('A mensagem ultrapassou o limite de ' + maxSize + ' caracteres!');
     return false;
  }

	if (document.torpedo.lentxt)
	{
		document.torpedo.lentxt.value = numCaracteres;
	}
	else
	{
		document.getElementById("torpedoLenTxt").innerHTML = numCaracteres;
	}


  return true;
}