l4/pkg/l4util/include/lock.h

   1 /*****************************************************************************/
   2 /**
   3  * \file
   4  * \brief   Simple lock implementation.
   5  *          Does only work if all thread have the same priority!
   6  *
   7  * \date    02/1997
   8  * \author  Michael Hohmuth <hohmuth@os.inf.tu-dresden.de> */
   9 /*
  10  * (c) 2000-2009 Author(s)
  11  *     economic rights: Technische Universität Dresden (Germany)
  12  * This file is part of TUD:OS and distributed under the terms of the
  13  * GNU Lesser General Public License 2.1.
  14  * Please see the COPYING-LGPL-2.1 file for details.
  15  */
  16
  17 /*****************************************************************************/
  18 #ifndef __L4UTIL_LOCK_H__
  19 #define __L4UTIL_LOCK_H__
  20
  21 #include <l4/sys/thread.h>
  22 #include <l4/sys/compiler.h>
  23 #include <l4/util/atomic.h>
  24
  25 EXTERN_C_BEGIN
  26
  27 typedef l4_uint32_t l4util_simple_lock_t;
  28
  29 L4_INLINE int  l4_simple_try_lock(l4util_simple_lock_t *lock);
  30 L4_INLINE void l4_simple_unlock(l4util_simple_lock_t *lock);
  31 L4_INLINE int  l4_simple_lock_locked(l4util_simple_lock_t *lock);
  32 L4_INLINE void l4_simple_lock_solid(register l4util_simple_lock_t *p);
  33 L4_INLINE void l4_simple_lock(l4util_simple_lock_t * lock);
  34
  35 L4_INLINE int
  36 l4_simple_try_lock(l4util_simple_lock_t *lock)
  37 {
  38   return l4util_xchg32(lock, 1) == 0;
  39 }
  40
  41 L4_INLINE void
  42 l4_simple_unlock(l4util_simple_lock_t *lock)
  43 {
  44   *lock = 0;
  45 }
  46
  47 L4_INLINE int
  48 l4_simple_lock_locked(l4util_simple_lock_t *lock)
  49 {
  50   return (*lock == 0) ? 0 : 1;
  51 }
  52
  53 L4_INLINE void
  54 l4_simple_lock_solid(register l4util_simple_lock_t *p)
  55 {
  56   while (l4_simple_lock_locked(p) || !l4_simple_try_lock(p))
  57     l4_thread_switch(L4_INVALID_CAP);
  58 }
  59
  60 L4_INLINE void
  61 l4_simple_lock(l4util_simple_lock_t * lock)
  62 {
  63   if (!l4_simple_try_lock(lock))
  64     l4_simple_lock_solid(lock);
  65 }
  66
  67 EXTERN_C_END
  68
  69 #endif