UNIX Portable Atomic Operations

Question

Is there a (POSIX-)portable way in C for atomic variable operations similar to a portable threading with pthread?

Atomic operations are operations like \"increment a

Answer 1

As of C11 there is an optional Atomic library which provides atomic operations. This is portable to whatever platform that has a C11 compiler (like gcc-4.9) with this optional feature.

The presence of the atomic can be checked with __STDC_NO_ATOMICS__and the presence of <stdatomic.h>

atomic.c

#include <stdio.h>
#include <stdlib.h>
#ifndef __STDC_NO_ATOMICS__
#include <stdatomic.h>
#endif

int main(int argc, char**argv) {
    _Atomic int a;
    atomic_init(&a, 42);
    atomic_store(&a, 5);
    int b = atomic_load(&a);
    printf("b = %i\n", b);

    return EXIT_SUCCESS;
}

Compiler invocations

clang -std=c11 atomic.c
gcc -std=c11 atomic.c