/*----------------------------------------------------------------------*/
/*                                                                      */
/*----------------------------------------------------------------------*/
function validarIngreso(form) {
  var ajax = objetoAjax();
  var sal = 0;

  var str = 'Por favor, revise los siguientes datos obligatorios:\n';
  var error = false;

  if (textoNulo(form.logUsr.value)) {
    str = str + '- Usuario\n';
    error = true;
  }

  if (textoNulo(form.logPas.value)) {
    str = str + '- Contraseņa\n';
    error = true;
  }

  if (error) {
    alert(str);
    return false;
  }

//  alert('Inicio[' + form.logUsr.value + '][' +  form.logPas.value + '][' + sal + ']');

  sal = 1;
  if (ajax) {
    ajax.onreadystatechange = function() {
//      if (ajax.readyState == 1  || ajax.readyState == "loading") {
//        document.getElementById('popUpIngreso').innerHTML = "<br /><br /><center><img src='./imagenes/cargando.gif' width='32' height='32' /><br /><br /></center>";
//      }
      if (ajax.readyState == 4 || ajax.readyState == "complete") {
        if (ajax.status == 200) {
//          alert(ajax.responseText);
          sal = ajax.responseText;
          if (sal == 0)
            alert('Usuario o password incorrectos');
        }
        else {
          alert("There was a problem while using XMLHTTP:\n" + ajax.statusText);
        }
      }
    }
     
//    ajax.open("GET", "usuariosExiste.php?uS="+form.logUsr.value+"&pA="+form.logPas.value, true);
    ajax.open("GET", "usuariosExiste.php?uS="+form.logUsr.value+"&pA="+form.logPas.value, false);
    ajax.send(null);
  }

  return (sal != 0);
}