/*
 * Copyright (c) 1995, 1996 Gunther Schadow.  All rights reserved.
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 * 
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 * 
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
 */
#include "pg_config.h"

IDENT("@(#) UniMesg.cc (Gunther Schadow) 12/19/96");

#pragma implementation

#include "UniMesg.h"

struct unif_rec
{
  UniMesIdCode::Value 
    uni_offset;
  EventTypeCode::Value
    evn_offset;
};

struct disp_rec
{
  MesTypeCode::Value
    message_type;
  EventTypeCode::Value
    event_type;
};


/* These are defined in UniMesg-conf.h
 *
 * struct unif_rec unif[MesTypeCode::size] =
 * struct disp_rec disp[UniMesIdCode::size] =
 */

#include "UniMesg-conf.h"

/* UniMesId() is a function that takes two arguments: a MesTypeCode (M)
 * and an EventTypeCode (E). It returns the UniMesIdCode (U).
 *
 * f: M x E --> U
 *
 * The composite ZMtyp (Z) is M x E, thus there is a polymorphism:
 *
 * f: f(m, e) ; m in M and e in E
 * f: f(z)    ; z in Z
 *
 * This function assumes that:
 * - The table for U lists message types in order of the table for M.
 * - The table for U keeps events for a message type together in the order
 *   of the table for E.
 * - The table for E lists event types for a message type together in the
 *   order of M.
 */

UniMesIdCode::Value
UniMesId(MesTypeCode::Value mes_type,
	 EventTypeCode::Value evn_type)
{
  struct unif_rec ur = unif[(int)mes_type - (int)MesTypeCode::first];
  if((ur.evn_offset != EventTypeCode::not_present)
     && (evn_type   != EventTypeCode::not_present))
    return (UniMesIdCode::Value)
      ((int)ur.uni_offset
       + (int)evn_type
       - (int)ur.evn_offset);
  else
    return ur.uni_offset;
}

UniMesIdCode::Value UniMesId(const ZMtyp &mid)
{
  return UniMesId((MesTypeCode::Value)mid.getMesId(), mid.getEventType());
}

/* The following functions are the inverse of UniMesId():
 *
 * f': U --> M x E
 *
 * MesType(U)   returns from M only,
 * EventType(U) returns from E only,
 * ZM(U)        returns from M x E as an ZMtyp composite.
 */

MesTypeCode::Value
MesType(UniMesIdCode::Value uni_mes)
{
  struct disp_rec dr = disp[(int)uni_mes - (int)UniMesIdCode::first];
  return dr.message_type;
}

EventTypeCode::Value
EventType(UniMesIdCode::Value uni_mes)
{
  struct disp_rec dr = disp[(int)uni_mes - (int)UniMesIdCode::first];
  return dr.event_type;
}

ZMtyp
ZM(UniMesIdCode::Value uni_mes) return r
{
  r.setMesId(MesType(uni_mes));
  r.setEventType(EventType(uni_mes));
}