The atomic_ops project (Atomic memory update operations portable implementation)
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The atomic_ops library (libatomic_ops)


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This is version 7.5.0 (next release development) of libatomic_ops.


You might find a more recent/stable version on the Download page, or BDWGC site.

Also, the latest bug fixes and new features are available in the development repository.


This package provides semi-portable access to hardware-provided atomic memory update operations on a number architectures. These might allow you to write code:

  • That does more interesting things in signal handlers.

  • Makes more effective use of multiprocessors by allowing you to write clever lock-free code. Note that such code is very difficult to get right, and will unavoidably be less portable than lock-based code. It is also not always faster than lock-based code. But it may occasionally be a large performance win.

  • To experiment with new and much better thread programming paradigms, etc.

For details and licensing restrictions see the files in the "doc" subdirectory.

Please address bug reports to mailing list.

Installation and Usage

The configuration and build scripts for this package were generated by Automake/Autoconf. "./configure; make; sudo make install" in this directory should work. For a more customized build, see the output of "./configure --help". To build it from the development repository, "./" should be executed first.

Note that much of the content of this library is in the header files. However, two small libraries are built and installed:

  • libatomic_ops.a is a support library, which is not needed on some platforms. This is intended to be usable, under some mild restrictions, in free or proprietary code, as are all the header files. See doc/LICENSING.txt.

  • libatomic_ops_gpl.a contains some higher level facilities. This code is currently covered by the GPL. The contents currently correspond to the headers atomic_ops_stack.h and atomic_ops_malloc.h.

Platform Specific Notes

Win32/64: src/Makefile.msft contains a very simple Makefile for building and running tests and building the gpl library. The core atomic_ops implementation is entirely in header files.

HP-UX/PA-RISC: aCC -Ae won't work as a C compiler, since it doesn't support inline assembly code. Use cc.

Copyright & Warranty

See doc/LICENSING.txt file.