vlc_atomic.h

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/*****************************************************************************
 * vlc_atomic.h:
 *****************************************************************************
 * Copyright (C) 2010 Rémi Denis-Courmont
 *
 * This program is free software; you can redistribute it and/or modify it
 * under the terms of the GNU Lesser General Public License as published by
 * the Free Software Foundation; either version 2.1 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
 * GNU Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public License
 * along with this program; if not, write to the Free Software Foundation,
 * Inc., 51 Franklin Street, Fifth Floor, Boston MA 02110-1301, USA.
 *****************************************************************************/

#ifndef VLC_ATOMIC_H
# define VLC_ATOMIC_H

/**
 * \file
 * Atomic operations do not require locking, but they are not very powerful.
 */

/** Static initializer for \ref vlc_atomic_t */
# define VLC_ATOMIC_INIT(val) { (val) }

/* All functions return the atom value _after_ the operation. */

VLC_API uintptr_t vlc_atomic_get(const vlc_atomic_t *);
VLC_API uintptr_t vlc_atomic_set(vlc_atomic_t *, uintptr_t);
VLC_API uintptr_t vlc_atomic_add(vlc_atomic_t *, uintptr_t);

static inline uintptr_t vlc_atomic_sub (vlc_atomic_t *atom, uintptr_t v)
{
    return vlc_atomic_add (atom, -v);
}

static inline uintptr_t vlc_atomic_inc (vlc_atomic_t *atom)
{
    return vlc_atomic_add (atom, 1);
}

static inline uintptr_t vlc_atomic_dec (vlc_atomic_t *atom)
{
    return vlc_atomic_sub (atom, 1);
}

VLC_API uintptr_t vlc_atomic_swap(vlc_atomic_t *, uintptr_t);
VLC_API uintptr_t vlc_atomic_compare_swap(vlc_atomic_t *, uintptr_t, uintptr_t);

/** Helper to retrieve a single precision from an atom. */
static inline float vlc_atomic_getf(const vlc_atomic_t *atom)
{
    union { float f; uintptr_t i; } u;
    u.i = vlc_atomic_get(atom);
    return u.f;
}

/** Helper to store a single precision into an atom. */
static inline float vlc_atomic_setf(vlc_atomic_t *atom, float f)
{
    union { float f; uintptr_t i; } u;
    u.f = f;
    vlc_atomic_set(atom, u.i);
    return f;
}

#endif