formal-model/spinlock/mem.spin

   1 /*
   2  * This program is free software; you can redistribute it and/or modify
   3  * it under the terms of the GNU General Public License as published by
   4  * the Free Software Foundation; either version 2 of the License, or
   5  * (at your option) any later version.
   6  *
   7  * This program is distributed in the hope that it will be useful,
   8  * but WITHOUT ANY WARRANTY; without even the implied warranty of
   9  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  10  * GNU General Public License for more details.
  11  *
  12  * You should have received a copy of the GNU General Public License
  13  * along with this program; if not, write to the Free Software
  14  * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
  15  *
  16  * Copyright (c) 2009 Mathieu Desnoyers
  17  */
  18
  19 byte lock = 0;
  20 byte refcount = 0;
  21
  22 inline spin_lock(lock)
  23 {
  24         do
  25         :: 1 -> atomic {
  26                         if
  27                         :: (lock) ->
  28                                 skip;
  29                         :: else ->
  30                                 lock = 1;
  31                                 break;
  32                         fi;
  33                 }
  34         od;
  35 }
  36
  37 inline spin_unlock(lock)
  38 {
  39         lock = 0;
  40 }
  41
  42 proctype proc_X()
  43 {
  44         do
  45         :: 1 ->
  46                 spin_lock(lock);
  47                 refcount = refcount + 1;
  48                 refcount = refcount - 1;
  49                 spin_unlock(lock);
  50         od;
  51 }
  52
  53 init
  54 {
  55         run proc_X();
  56         run proc_X();
  57 }