OFAtomic.h

/*
 * Copyright (c) 2008-2026 Jonathan Schleifer <js@nil.im>
 *
 * All rights reserved.
 *
 * This program is free software: you can redistribute it and/or modify it
 * under the terms of the GNU Lesser General Public License version 3.0 only,
 * as published by the Free Software Foundation.
 *
 * 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
 * version 3.0 for more details.
 *
 * You should have received a copy of the GNU Lesser General Public License
 * version 3.0 along with this program. If not, see
 * <https://www.gnu.org/licenses/>.
 */

#include <stdlib.h>

#import "macros.h"

#ifndef OF_HAVE_ATOMIC_OPS
# error No atomic operations available!
#endif

#if !defined(OF_HAVE_THREADS)
static OF_INLINE int
OFAtomicIntAdd(volatile int *_Nonnull p, int i)
{
    return (*p += i);
}

static OF_INLINE void *_Nullable
OFAtomicPointerAdd(void *volatile _Nullable *_Nonnull p, intptr_t i)
{
    return (*(char *volatile *)p += i);
}

static OF_INLINE int
OFAtomicIntSubtract(volatile int *_Nonnull p, int i)
{
    return (*p -= i);
}

static OF_INLINE void *_Nullable
OFAtomicPointerSubtract(void *volatile _Nullable *_Nonnull p, intptr_t i)
{
    return (*(char *volatile *)p -= i);
}

static OF_INLINE int
OFAtomicIntIncrease(volatile int *_Nonnull p)
{
    return ++*p;
}

static OF_INLINE int
OFAtomicIntDecrease(volatile int *_Nonnull p)
{
    return --*p;
}

static OF_INLINE unsigned int
OFAtomicIntOr(volatile unsigned int *_Nonnull p, unsigned int i)
{
    return (*p |= i);
}

static OF_INLINE unsigned int
OFAtomicIntAnd(volatile unsigned int *_Nonnull p, unsigned int i)
{
    return (*p &= i);
}

static OF_INLINE bool
OFAtomicIntCompareAndSwap(volatile int *_Nonnull p, int o, int n)
{
    if (*p == o) {
        *p = n;
        return true;
    }

    return false;
}

static OF_INLINE bool
OFAtomicPointerCompareAndSwap(void *volatile _Nullable *_Nonnull p,
    void *_Nullable o, void *_Nullable n)
{
    if (*p == o) {
        *p = n;
        return true;
    }

    return false;
}

static OF_INLINE void
OFMemoryBarrier(void)
{
    /* nop */
}

static OF_INLINE void
OFAcquireMemoryBarrier(void)
{
    /* nop */
}

static OF_INLINE void
OFReleaseMemoryBarrier(void)
{
    /* nop */
}
#elif (defined(OF_AMD64) || defined(OF_X86)) && defined(__GNUC__)
# import "platform/x86/OFAtomic.h"
#elif defined(OF_POWERPC) && defined(__GNUC__) && !defined(__APPLE_CC__) && \
    !defined(OF_AIX)
# import "platform/PowerPC/OFAtomic.h"
#elif defined(OF_HAVE_ATOMIC_BUILTINS)
# import "platform/GCC4.7/OFAtomic.h"
#elif defined(OF_HAVE_SYNC_BUILTINS)
# import "platform/GCC4/OFAtomic.h"
#elif defined(OF_HAVE_OSATOMIC)
# import "platform/macOS/OFAtomic.h"
#else
# error No atomic operations available!
#endif