kernel/core/mutex.c

   1 /*
   2  *  ZeX/OS
   3  *  Copyright (C) 2007  Tomas 'ZeXx86' Jedrzejek (zexx86@zexos.org)
   4  *
   5  *  This program is free software: you can redistribute it and/or modify
   6  *  it under the terms of the GNU General Public License as published by
   7  *  the Free Software Foundation, either version 3 of the License, or
   8  *  (at your option) any later version.
   9  *
  10  *  This program is distributed in the hope that it will be useful,
  11  *  but WITHOUT ANY WARRANTY; without even the implied warranty of
  12  *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  13  *  GNU General Public License for more details.
  14  *
  15  *  You should have received a copy of the GNU General Public License
  16  *  along with this program.  If not, see <http://www.gnu.org/licenses/>.
  17  */
  18
  19
  20 #include <system.h>
  21 #include <mutex.h>
  22
  23 unsigned mutex_lock (mutex_t *mutex)
  24 {
  25         if (!mutex)
  26                 return 0;
  27
  28         /* wait until mutex is unlocked */
  29         while (mutex->locked) {
  30                 /* hop to next task */
  31                 schedule ();
  32         }
  33
  34         /* increase mutex lock */
  35         mutex->locked ++;
  36
  37         return 1;
  38 }
  39
  40 unsigned mutex_unlock (mutex_t *mutex)
  41 {
  42         if (!mutex)
  43                 return 0;
  44
  45         if (!mutex->locked)
  46                 return 0;
  47
  48         mutex->locked --;
  49
  50         return 1;
  51 }
  52
  53 unsigned mutex_init (mutex_t *mutex)
  54 {
  55         if (!mutex)
  56                 return 0;
  57
  58         mutex->locked = 0;
  59 }