I've made so many changes I don't dare continue until I check the current stuff in. /test/testatomic.c performs absolutely basic tests to show that the function work as expected. Need a second test to do more detailed tests. /include/SDL_atomic.h provides declarations for all included functions. /src/atomic/linux/SDL_atomic.c provided all the functions. On a generic built the 64 bit functions work, but they are emulated. On a build for -march=pentium and above the 64 bit functions use native instructions /src/atomic/dummy/SDL_atomic.c emulates all the operations using SDL_mutex.h. /src/atomic/win32/SDL_atomic.c is a copy of dummy /src/atomic/macosx/SDL_atomic.s is a copy of dummy These versions of SDL_atomic.c provide a frame work for building the library with a mixture of native and emulated functions. This allows the whole library to be provided on all platforms. (I hope.) I hope this fits with the SDL philosophy of either providing a common subset or emulating when the platform is missing a feature. I have not added dummy, macosx, or win32 to the build. They are there as place holders for future work. I have modified congifure.in to compile sources in /src/atomic/linux. (The SDL configure.in file is an amazing piece of work and I hope I didn't mess it up. :-)

#include <stdlib.h>
#include <stdio.h>

#include "common.h"

static CommonState *state;

/* Call this instead of exit(), so we can clean up SDL: atexit() is evil. */
static void
quit(int rc)
{
    CommonQuit(state);
    exit(rc);
}

int
main(int argc, char *argv[])
{
    int i, done;
    SDL_Event event;

    /* Initialize test framework */
    state = CommonCreateState(argv, SDL_INIT_VIDEO);
    if (!state) {
        return 1;
    }
    state->skip_renderer = SDL_TRUE;
    for (i = 1; i < argc;) {
        int consumed;

        consumed = CommonArg(state, i);
        if (consumed == 0) {
            consumed = -1;
        }
        if (consumed < 0) {
            fprintf(stderr, "Usage: %s %s\n", argv[0], CommonUsage(state));
            quit(1);
        }
        i += consumed;
    }
    if (!CommonInit(state)) {
        quit(2);
    }

    /* Main render loop */
    done = 0;
    while (!done) {
        /* Check for events */
        while (SDL_PollEvent(&event)) {
            CommonEvent(state, &event, &done);
        }
    }
    quit(0);
}

/* vi: set ts=4 sw=4 expandtab: */