README.md
1# The atomic_ops library (`libatomic_ops`)
2
3IN NEW CODE, PLEASE USE C11 OR C++14 STANDARD ATOMICS INSTEAD OF THIS PACKAGE.
4
5This is version 7.6.12 of libatomic_ops.
6
7
8## Download
9
10You might find a more recent/stable version on the
11[Download](https://github.com/ivmai/libatomic_ops/wiki/Download) page, or
12[BDWGC site](http://www.hboehm.info/gc/).
13
14Also, the latest bug fixes and new features are available in the
15[development repository](https://github.com/ivmai/libatomic_ops).
16
17
18## Overview
19
20This package provides semi-portable access to hardware-provided
21atomic memory update operations on a number of architectures. These might
22allow you to write code:
23
24* That does more interesting things in signal handlers.
25
26* Makes more effective use of multiprocessors by allowing you to write
27 clever lock-free code. Note that such code is very difficult to get
28 right, and will unavoidably be less portable than lock-based code. It
29 is also not always faster than lock-based code. But it may occasionally
30 be a large performance win.
31
32* To experiment with new and much better thread programming paradigms, etc.
33
34For details and licensing restrictions see the files in the "doc"
35subdirectory.
36
37
38## Installation and Usage
39
40The configuration and build scripts for this package were generated by
41Automake/Autoconf. `./configure; make; sudo make install` in this
42directory should work. For a more customized build, see the output of
43`./configure --help`. To build it from the development repository,
44`./autogen.sh` should be executed first.
45
46Note that much of the content of this library is in the header files.
47However, two small libraries are built and installed:
48
49* `libatomic_ops.a` is a support library, which is not needed on some
50 platforms. This is intended to be usable, under some mild restrictions,
51 in free or proprietary code, as are all the header files.
52 See doc/LICENSING.txt.
53
54* `libatomic_ops_gpl.a` contains some higher level facilities. This code is
55 currently covered by the GPL. The contents currently correspond to
56 the headers `atomic_ops_stack.h` and `atomic_ops_malloc.h`.
57
58
59## Platform Specific Notes
60
61Win32/64: src/Makefile.msft contains a very simple Makefile for building
62and running tests and building the gpl library. The core `libatomic_ops`
63implementation is entirely in header files.
64
65HP-UX/PA-RISC: `aCC -Ae` won't work as a C compiler, since it doesn't support
66inline assembly code. Use cc.
67
68
69## Feedback, Contribution, Questions and Notifications
70
71Please address bug reports and new feature ideas to
72[GitHub issues](https://github.com/ivmai/libatomic_ops/issues). Before the
73submission please check that it has not been done yet by someone else.
74
75If you want to contribute, submit
76a [pull request](https://github.com/ivmai/libatomic_ops/pulls) to GitHub.
77
78If you need help, use
79[Stack Overflow](https://stackoverflow.com/questions/tagged/atomic-ops).
80Older questions on the site can be found by
81[this query](https://stackoverflow.com/search?q=atomic_ops).
82Older technical discussions are also available in `bdwgc` mailing list
83archive - it can be downloaded as a
84[compressed file](https://github.com/ivmai/bdwgc/files/1038163/bdwgc-mailing-list-archive-2017_04.tar.gz)
85or browsed at [Narkive](http://bdwgc.opendylan.narkive.com) (please search
86for _atomic_ keyword).
87
88To get new release announcements, subscribe to
89[RSS feed](https://github.com/ivmai/libatomic_ops/releases.atom).
90(To receive the notifications by email, a 3rd-party free service like
91[IFTTT RSS Feed](https://ifttt.com/feed) can be setup.)
92To be notified on all issues, please
93[watch](https://github.com/ivmai/libatomic_ops/watchers) the project on
94GitHub.
95
96
97## Copyright & Warranty
98
99 * Copyright (c) 1991-1994 by Xerox Corporation. All rights reserved.
100 * Copyright (c) 1996-1999 by Silicon Graphics. All rights reserved.
101 * Copyright (c) 1999-2011 Hewlett-Packard Development Company, L.P.
102 * Copyright (c) 2008-2021 Ivan Maidanski
103
104The file armcc/arm_v6.h is also
105
106 * Copyright (c) 2007 by NEC LE-IT. All rights reserved.
107
108The file gcc/avr32.h is
109
110 * Copyright (c) 2009 Bradley Smith <brad@brad-smith.co.uk>
111
112The file gcc/mips.h is
113
114 * Copyright (c) 2005, 2007 Thiemo Seufer <ths@networkno.de>
115
116The file gcc/sh.h is
117
118 * Copyright (c) 2009 by Takashi YOSHII. All rights reserved.
119
120See [LICENSING.txt](doc/LICENSING.txt) for the details.
121