Toward generic atomic operations

I realize that this is Linux Weekly News, but since when was Linux the only platform with pthreads support? Heck, even Windows has pthreads-win32. The only platform I know of with broken pthreads is OpenBSD, which is going through a messy transition from user threads to 1:1 pre-emptive threading. (I say broken because some signal handling is presently fubar.) The reason people roll their own threading library isn't because they want to be portable to non-Linux, it's because they want to be "portable" to Windows. That's a tremendous distinction. (Also, it's because rolling your own threading API is one of those low-level tasks that's enticing to people who still think of C as a high-level assembler, aching to be abused.)

And, unless I'm mistaken, both GCC and clang have the capability to support <stdatomic.h>, they just don't ship with that header. But all the way back to GCC 4.1'ish (an eternity ago), GCC has had atomic primitives, based on a proposed Intel specification and which bares more than a passing resemblance to the C11 and C++11 API. If you want <stdatomic.h> you can find an implementation based on GCC and clang intrinsics here,

http://svnweb.freebsd.org/base/head/include/stdatomic.h?v...

I'm not sure if it's 100% complete, but for all the basic stuff (increment, store, load, compare-and-swap), it should suffice.