atomic.h 1.8 KB

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  1. /* Copyright (C) 2003 Free Software Foundation, Inc.
  2. This file is part of the GNU C Library.
  3. Contributed by Ulrich Drepper <drepper@redhat.com>, 2003.
  4. The GNU C Library is free software; you can redistribute it and/or
  5. modify it under the terms of the GNU Lesser General Public
  6. License as published by the Free Software Foundation; either
  7. version 2.1 of the License, or (at your option) any later version.
  8. The GNU C Library is distributed in the hope that it will be useful,
  9. but WITHOUT ANY WARRANTY; without even the implied warranty of
  10. MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
  11. Lesser General Public License for more details.
  12. You should have received a copy of the GNU Lesser General Public
  13. License along with the GNU C Library; if not, write to the Free
  14. Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
  15. 02111-1307 USA. */
  16. #ifndef _BITS_ATOMIC_H
  17. #define _BITS_ATOMIC_H 1
  18. /* We have by default no support for atomic operations. So define
  19. them non-atomic. If this is a problem somebody will have to come
  20. up with real definitions. */
  21. /* The only basic operation needed is compare and exchange. */
  22. #define atomic_compare_and_exchange_val_acq(mem, newval, oldval) \
  23. ({ __typeof (mem) __gmemp = (mem); \
  24. __typeof (*mem) __gret = *__gmemp; \
  25. __typeof (*mem) __gnewval = (newval); \
  26. \
  27. if (__gret == (oldval)) \
  28. *__gmemp = __gnewval; \
  29. __gret; })
  30. #define atomic_compare_and_exchange_bool_acq(mem, newval, oldval) \
  31. ({ __typeof (mem) __gmemp = (mem); \
  32. __typeof (*mem) __gnewval = (newval); \
  33. \
  34. *__gmemp == (oldval) ? (*__gmemp = __gnewval, 0) : 1; })
  35. #endif /* bits/atomic.h */