/* Macro definitions for defining and using ioctl-based RPC interfaces.
   Copyright (C) 1999 Free Software Foundation, Inc.

This file is part of the GNU Hurd.

The GNU Hurd 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, or (at your option)
any later version.

The GNU Hurd 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 the GNU Hurd; see the file COPYING.  If not, write to
the Free Software Foundation, 675 Mass Ave, Cambridge, MA 02139, USA.  */

#ifndef _HURD_IOCTLS_DEFS
#define _HURD_IOCTLS_DEFS 1

#ifndef _SYS_IOCTL_H
#define _SYS_IOCTL_H		/* Suppress #error in <bits/ioctl.h>.  */
#endif
#include <bits/ioctls.h>


/* Calculate the MiG subsystem (i.e. first message ID)
   for the RPCs produced by ioctl requests in the given group.  */
#define IOC_GROUP_SUBSYSTEM(group)	(100000 + ((group) - 'f') * 4000)

/* Because of MiG's poorly chosen algorithm of adding 100 to a request
   msgid to produce the reply msgid, we cannot just add the command part of
   the ioctl request to the subsystem base msgid.  For ioctl requests past
   99, we must skip blocks of 100 msgids to allow for the reply msgids
   corresponding to the earlier requests.  Since our ioctl request format
   allows only 7 bits for the command portion, we know that it cannot
   exceed 127 and thus we can handle just 100+ as a special case.  */
#define IOC_COMMAND_SUBID(cmd)		((cmd) + ((cmd) < 100 ? 0 : 100))

#define IOC_CONSTRUCT_MSGID(group, cmd)		\
  (IOC_GROUP_SUBSYSTEM (group) + IOC_COMMAND_SUBID (cmd))
#define IOC_MSGID(request)	\
  IOC_CONSTRUCT_MSGID (_IOC_GROUP (request), _IOC_COMMAND (request))


#endif /* !_HURD_IOCTLS_DEFS */