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/*
 * Copyright (c) 2015-16  David Lamparter, for NetDEF, Inc.
 *
 * Permission to use, copy, modify, and distribute this software for any
 * purpose with or without fee is hereby granted, provided that the above
 * copyright notice and this permission notice appear in all copies.
 *
 * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
 * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
 * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
 * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
 */

#ifndef _FRRATOMIC_H
#define _FRRATOMIC_H

#ifdef HAVE_CONFIG_H
#include "config.h"
#endif

#ifndef FRR_AUTOCONF_ATOMIC
#error autoconf checks for atomic functions were not properly run
#endif

/* ISO C11 */
#ifdef HAVE_STDATOMIC_H
#include <stdatomic.h>

/* gcc 4.7 and newer */
#elif defined(HAVE___ATOMIC)

#define _Atomic volatile

#define memory_order_relaxed __ATOMIC_RELAXED
#define memory_order_consume __ATOMIC_CONSUME
#define memory_order_acquire __ATOMIC_ACQUIRE
#define memory_order_release __ATOMIC_RELEASE
#define memory_order_acq_rel __ATOMIC_ACQ_REL
#define memory_order_seq_cst __ATOMIC_SEQ_CST

#define atomic_load_explicit __atomic_load_n
#define atomic_store_explicit __atomic_store_n
#define atomic_exchange_explicit __atomic_exchange_n
#define atomic_fetch_add_explicit __atomic_fetch_add
#define atomic_fetch_sub_explicit __atomic_fetch_sub

#define atomic_compare_exchange_weak_explicit(atom, expect, desire, mem1, mem2) \
	__atomic_compare_exchange_n(atom, expect, desire, 1, mem1, mem2)

/* gcc 4.1 and newer,
 * clang 3.3 (possibly older)
 *
 * __sync_swap isn't in gcc's documentation, but clang has it
 *
 * note __sync_synchronize() 
 */
#elif defined(HAVE___SYNC)

#define _Atomic volatile

#define memory_order_relaxed 0
#define memory_order_consume 0
#define memory_order_acquire 0
#define memory_order_release 0
#define memory_order_acq_rel 0
#define memory_order_seq_cst 0

#define atomic_load_explicit(ptr, mem) \
	({ __sync_synchronize(); \
	   typeof(*ptr) rval = __sync_fetch_and_add((ptr), 0); \
	   __sync_synchronize(); rval; })
#define atomic_store_explicit(ptr, val, mem) \
	({ __sync_synchronize(); \
	   *(ptr) = (val); \
	   __sync_synchronize(); (void)0; })
#ifdef HAVE___SYNC_SWAP
#define atomic_exchange_explicit(ptr, val, mem) \
	({ __sync_synchronize(); \
	   typeof(*ptr) rval = __sync_swap((ptr, val), 0); \
	   __sync_synchronize(); rval; })
#else /* !HAVE___SYNC_SWAP */
#define atomic_exchange_explicit(ptr, val, mem) \
	({ typeof(ptr) _ptr = (ptr); typeof(val) _val = (val); \
	   __sync_synchronize(); \
	   typeof(*ptr) old1, old2 = __sync_fetch_and_add(_ptr, 0); \
	   do { \
		old1 = old2; \
		old2 = __sync_val_compare_and_swap (_ptr, old1, _val); \
	   } while (old1 != old2); \
	   __sync_synchronize(); \
	   old2; \
	})
#endif /* !HAVE___SYNC_SWAP */
#define atomic_fetch_add_explicit(ptr, val, mem) \
	({ __sync_synchronize(); \
	   typeof(*ptr) rval = __sync_fetch_and_add((ptr), (val)); \
	   __sync_synchronize(); rval; })
#define atomic_fetch_sub_explicit(ptr, val, mem) \
	({ __sync_synchronize(); \
	   typeof(*ptr) rval = __sync_fetch_and_sub((ptr), (val)); \
	   __sync_synchronize(); rval; })

#define atomic_compare_exchange_weak_explicit(atom, expect, desire, mem1, mem2) \
	({ typeof(atom) _atom = (atom); typeof(expect) _expect = (expect); \
	   typeof(desire) _desire = (desire); \
	   __sync_synchronize(); \
	   typeof(*atom) rval = __sync_val_compare_and_swap(_atom, *_expect, _desire); \
	   __sync_synchronize(); \
	   bool ret = (rval == *_expect); *_expect = rval; ret; })

#else /* !HAVE___ATOMIC && !HAVE_STDATOMIC_H */
#error no atomic functions...
#endif

#endif /* _FRRATOMIC_H */