atomic/unix/builtins64.c

/* Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You under the Apache License, Version 2.0
 * (the "License"); you may not use this file except in compliance with
 * the License.  You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

#include "apr_arch_atomic.h"

#ifdef USE_ATOMICS_BUILTINS64

#if defined(__i386__) || defined(__x86_64__) \
    || defined(__s390__) || defined(__s390x__)
#define WEAK_MEMORY_ORDERING 0
#else
#define WEAK_MEMORY_ORDERING 1
#endif

APR_DECLARE(apr_uint64_t) apr_atomic_read64(volatile apr_uint64_t *mem)
{
#if HAVE__ATOMIC_BUILTINS64
    return __atomic_load_n(mem, __ATOMIC_SEQ_CST);
#elif WEAK_MEMORY_ORDERING || APR_SIZEOF_VOIDP < 8
    /* No __sync_load() available => apr_atomic_add64(mem, 0) */
    return __sync_fetch_and_add(mem, 0);
#else
    return *mem;
#endif
}

APR_DECLARE(void) apr_atomic_set64(volatile apr_uint64_t *mem, apr_uint64_t val)
{
#if HAVE__ATOMIC_BUILTINS64
    __atomic_store_n(mem, val, __ATOMIC_SEQ_CST);
#elif WEAK_MEMORY_ORDERING || APR_SIZEOF_VOIDP < 8
    /* No __sync_store() available => apr_atomic_xchg64(mem, val) */
    __sync_synchronize();
    __sync_lock_test_and_set(mem, val);
#else
    *mem = val;
#endif
}

APR_DECLARE(apr_uint64_t) apr_atomic_add64(volatile apr_uint64_t *mem, apr_uint64_t val)
{
#if HAVE__ATOMIC_BUILTINS64
    return __atomic_fetch_add(mem, val, __ATOMIC_SEQ_CST);
#else
    return __sync_fetch_and_add(mem, val);
#endif
}

APR_DECLARE(void) apr_atomic_sub64(volatile apr_uint64_t *mem, apr_uint64_t val)
{
#if HAVE__ATOMIC_BUILTINS64
    __atomic_fetch_sub(mem, val, __ATOMIC_SEQ_CST);
#else
    __sync_fetch_and_sub(mem, val);
#endif
}

APR_DECLARE(apr_uint64_t) apr_atomic_inc64(volatile apr_uint64_t *mem)
{
#if HAVE__ATOMIC_BUILTINS64
    return __atomic_fetch_add(mem, 1, __ATOMIC_SEQ_CST);
#else
    return __sync_fetch_and_add(mem, 1);
#endif
}

APR_DECLARE(int) apr_atomic_dec64(volatile apr_uint64_t *mem)
{
#if HAVE__ATOMIC_BUILTINS64
    return __atomic_sub_fetch(mem, 1, __ATOMIC_SEQ_CST);
#else
    return __sync_sub_and_fetch(mem, 1);
#endif
}

APR_DECLARE(apr_uint64_t) apr_atomic_cas64(volatile apr_uint64_t *mem, apr_uint64_t val,
                                           apr_uint64_t cmp)
{
#if HAVE__ATOMIC_BUILTINS64
    __atomic_compare_exchange_n(mem, &cmp, val, 0, __ATOMIC_SEQ_CST, __ATOMIC_SEQ_CST);
    return cmp;
#else
    return __sync_val_compare_and_swap(mem, cmp, val);
#endif
}

APR_DECLARE(apr_uint64_t) apr_atomic_xchg64(volatile apr_uint64_t *mem, apr_uint64_t val)
{
#if HAVE__ATOMIC_BUILTINS64
    return __atomic_exchange_n(mem, val, __ATOMIC_SEQ_CST);
#else
    __sync_synchronize();
    return __sync_lock_test_and_set(mem, val);
#endif
}

#endif /* USE_ATOMICS_BUILTINS64 */