include/vlc_atomic.h

   1 /*****************************************************************************
   2  * vlc_atomic.h:
   3  *****************************************************************************
   4  * Copyright (C) 2010 Rémi Denis-Courmont
   5  *
   6  * This program is free software; you can redistribute it and/or modify
   7  * it under the terms of the GNU General Public License as published by
   8  * the Free Software Foundation; either version 2 of the License, or
   9  * (at your option) any later version.
  10  *
  11  * This program is distributed in the hope that it will be useful,
  12  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  13  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  14  * GNU General Public License for more details.
  15  *
  16  * You should have received a copy of the GNU General Public License
  17  * along with this program; if not, write to the Free Software
  18  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston MA 02110-1301, USA.
  19  *****************************************************************************/
  20
  21 #ifndef VLC_ATOMIC_H
  22 # define VLC_ATOMIC_H
  23
  24 /**
  25  * \file
  26  * Atomic operations do not require locking, but they are not very powerful.
  27  */
  28
  29 /** Static initializer for \ref vlc_atomic_t */
  30 # define VLC_ATOMIC_INIT(val) { (val) }
  31
  32 /* All functions return the atom value _after_ the operation. */
  33
  34 VLC_API uintptr_t vlc_atomic_get(const vlc_atomic_t *);
  35 VLC_API uintptr_t vlc_atomic_set(vlc_atomic_t *, uintptr_t);
  36 VLC_API uintptr_t vlc_atomic_add(vlc_atomic_t *, uintptr_t);
  37
  38 static inline uintptr_t vlc_atomic_sub (vlc_atomic_t *atom, uintptr_t v)
  39 {
  40     return vlc_atomic_add (atom, -v);
  41 }
  42
  43 static inline uintptr_t vlc_atomic_inc (vlc_atomic_t *atom)
  44 {
  45     return vlc_atomic_add (atom, 1);
  46 }
  47
  48 static inline uintptr_t vlc_atomic_dec (vlc_atomic_t *atom)
  49 {
  50     return vlc_atomic_sub (atom, 1);
  51 }
  52
  53 VLC_API uintptr_t vlc_atomic_swap(vlc_atomic_t *, uintptr_t);
  54 VLC_API uintptr_t vlc_atomic_compare_swap(vlc_atomic_t *, uintptr_t, uintptr_t);
  55
  56 /** Helper to retrieve a single precision from an atom. */
  57 static inline float vlc_atomic_getf(const vlc_atomic_t *atom)
  58 {
  59     union { float f; uintptr_t i; } u;
  60     u.i = vlc_atomic_get(atom);
  61     return u.f;
  62 }
  63
  64 /** Helper to store a single precision into an atom. */
  65 static inline float vlc_atomic_setf(vlc_atomic_t *atom, float f)
  66 {
  67     union { float f; uintptr_t i; } u;
  68     u.f = f;
  69     vlc_atomic_set(atom, u.i);
  70     return f;
  71 }
  72
  73 #endif