hash

static VALUE
BigDecimal_hash(VALUE self)
{
    ENTER(1);
    Real *p;
    U_LONG hash,i;

    GUARD_OBJ(p,GetVpValue(self,1));
    hash = (U_LONG)p->sign;
    /* hash!=2: the case for 0(1),NaN(0) or +-Infinity(3) is sign itself */
    if(hash==2) {
        for(i = 0; i < p->Prec;i++) {
            hash = 31 * hash + p->frac[i];
            hash ^= p->frac[i];
        }
        hash += p->exponent;
    }
    return INT2FIX(hash);
}