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. :-)

/*
 *	common.c
 *	written by Holmes Futrell
 *	use however you want
 */

#include "common.h"
#include "SDL.h"
#include <stdlib.h>

/*
	Produces a random int x, min <= x <= max 
	following a uniform distribution
*/
int
randomInt(int min, int max)
{
    return min + rand() % (max - min + 1);
}

/*
	Produces a random float x, min <= x <= max 
	following a uniform distribution
 */
float
randomFloat(float min, float max)
{
    return rand() / (float) RAND_MAX *(max - min) + min;
}

void
fatalError(const char *string)
{
    printf("%s: %s\n", string, SDL_GetError());
    exit(1);
}