For the following examplified ASN.1,

  TEST DEFINITIONS AUTOMATIC TAGS ::=
  BEGIN

  S1 ::= SEQUENCE  {
    fn INTEGER,
    fb BIT STRING DEFAULT 'A5'H,
    fc OCTET STRING DEFAULT 'FFAABB'H
  }

  END

and input XER as :

  <S1>
    <fn>9845</fn>
    <fc>DEAD9</fc>
  </S1>

The encoded APER should be :

  S1 ::= {
    fn: 9845
    fb: A5
    fc: DE AD 90
  }

but current output is

  S1 ::= {
    fn: 9845
    fb: A5
    fc: FF AA BB
  }

The reason is in SEQUENCE_encode_aper(), default_value_cmp() are
incorrectly checked against 1.

If the input value is equal to default value, this return value from
compare function is 0.