kinetic-c  v0.12.0
Seagate Kinetic Protocol Client Library for C
atomic.h
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1 /*
2 * kinetic-c
3 * Copyright (C) 2015 Seagate Technology.
4 *
5 * This program is free software; you can redistribute it and/or
6 * modify it under the terms of the GNU General Public License
7 * as published by the Free Software Foundation; either version 2
8 * of the License, or (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, write to the Free Software
17 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
18 *
19 */
20 #ifndef ATOMIC_H
21 #define ATOMIC_H
22 
23 /* Compiler intrinsic for an atomic compare-and-swap.
24  * Returns true if *PTR has been atomically changed from
25  * OLD to NEW, or false if OLD is no longer the current value
26  * (typically, because another thread changed it first). */
27 #define ATOMIC_BOOL_COMPARE_AND_SWAP(PTR, OLD, NEW) \
28  (__sync_bool_compare_and_swap(PTR, OLD, NEW))
29 
30 /* Spin attempting to atomically adjust F by ADJ until successful */
31 #define SPIN_ADJ(F, ADJ) \
32  do { \
33  for (;;) { \
34  size_t v = F; \
35  if (ATOMIC_BOOL_COMPARE_AND_SWAP(&F, v, v + ADJ)) { \
36  break; \
37  } \
38  } \
39  } while (0)
40 
41 #endif