/*  Copyright (C) 2024 CZ.NIC, z.s.p.o. <knot-dns@labs.nic.cz>

    This program is free software: you can redistribute it and/or modify
    it under the terms of the GNU General Public License as published by
    the Free Software Foundation, either version 3 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 General Public License for more details.

    You should have received a copy of the GNU General Public License
    along with this program.  If not, see <https://www.gnu.org/licenses/>.
 */

/*!
 * \brief C11 atomic operations with fallbacks.
 */

#pragma once

#ifdef HAVE_C11_ATOMIC           /* C11 */
 #define KNOT_HAVE_ATOMIC

 #include <stdatomic.h>

 #define ATOMIC_SET(dst, val)  atomic_store_explicit(&(dst), (val), memory_order_relaxed)
 #define ATOMIC_GET(src)       atomic_load_explicit(&(src), memory_order_relaxed)
 #define ATOMIC_ADD(dst, val)  (void)atomic_fetch_add_explicit(&(dst), (val), memory_order_relaxed)
 #define ATOMIC_SUB(dst, val)  (void)atomic_fetch_sub_explicit(&(dst), (val), memory_order_relaxed)
 #define ATOMIC_XCHG(dst, val) atomic_exchange_explicit(&(dst), (val), memory_order_relaxed)

 typedef atomic_uint_fast16_t knot_atomic_uint16_t;
 typedef atomic_uint_fast64_t knot_atomic_uint64_t;
 typedef atomic_size_t knot_atomic_size_t;
 typedef _Atomic (void *) knot_atomic_ptr_t;
 typedef atomic_bool knot_atomic_bool;
#elif defined(HAVE_GCC_ATOMIC)   /* GCC __atomic */
 #define KNOT_HAVE_ATOMIC

 #include <stdint.h>
 #include <stdbool.h>

 #define ATOMIC_SET(dst, val)  __atomic_store_n(&(dst), (val), __ATOMIC_RELAXED)
 #define ATOMIC_GET(src)       __atomic_load_n(&(src), __ATOMIC_RELAXED)
 #define ATOMIC_ADD(dst, val)  __atomic_add_fetch(&(dst), (val), __ATOMIC_RELAXED)
 #define ATOMIC_SUB(dst, val)  __atomic_sub_fetch(&(dst), (val), __ATOMIC_RELAXED)
 #define ATOMIC_XCHG(dst, val) __atomic_exchange_n(&(dst), (val), __ATOMIC_RELAXED)

 typedef uint16_t knot_atomic_uint16_t;
 typedef uint64_t knot_atomic_uint64_t;
 typedef size_t knot_atomic_size_t;
 typedef void* knot_atomic_ptr_t;
 typedef bool knot_atomic_bool;
#else                            /* Fallback, non-atomic. */
 #warning "Atomic operations not availabe, using unreliable replacement."

 #include <stdint.h>
 #include <stdbool.h>

 #define ATOMIC_SET(dst, val)  ((dst) = (val))
 #define ATOMIC_GET(src)       (src)
 #define ATOMIC_ADD(dst, val)  ((dst) += (val))
 #define ATOMIC_SUB(dst, val)  ((dst) -= (val))
 #define ATOMIC_XCHG(dst, val) ({ __typeof__ (dst) _z = (dst); (dst) = (val); _z; })

 typedef uint16_t knot_atomic_uint16_t;
 typedef uint64_t knot_atomic_uint64_t;
 typedef size_t knot_atomic_size_t;
 typedef void* knot_atomic_ptr_t;
 typedef bool knot_atomic_bool;
#endif