include(CheckCXXSourceCompiles)

set (atomic_test_sources "#include <atomic>
#include <cstdint>

void test(volatile std::atomic<std::int64_t> &a)
{
    std::int64_t v = a.load(std::memory_order_acquire);
    while (!a.compare_exchange_strong(v, v + 1,
                                      std::memory_order_acq_rel,
                                      std::memory_order_acquire)) {
        v = a.exchange(v - 1);
    }
    a.store(v + 1, std::memory_order_release);
}

int main(int, char **)
{
    void *ptr = (void*)0xffffffc0; // any random pointer
    test(*reinterpret_cast<std::atomic<std::int64_t> *>(ptr));
    return 0;
}")

check_cxx_source_compiles("${atomic_test_sources}" HAVE_STDATOMIC)
if(NOT HAVE_STDATOMIC)
    set(_req_libraries "${CMAKE_REQUIRE_LIBRARIES}")
    set(CMAKE_REQUIRE_LIBRARIES "atomic")
    check_cxx_source_compiles("${atomic_test_sources}" HAVE_STDATOMIC_WITH_LIB)
    set(CMAKE_REQUIRE_LIBRARIES "${_req_libraries}")
endif()

add_library(Atomic INTERFACE)
if(HAVE_STDATOMIC_WITH_LIB)
    target_link_libraries(Atomic INTERFACE atomic)
endif()

set(Atomic_FOUND 1)