MIT License (core library) / GPL-2.0 (gpl extension library)

Copyright (c) 1991-1994 by Xerox Corporation.  All rights reserved.
Copyright (c) 1996-1999 by Silicon Graphics.  All rights reserved.
Copyright (c) 1999-2011 Hewlett-Packard Development Company, L.P.
Copyright (c) 2005, 2007 Thiemo Seufer
Copyright (c) 2007 by NEC LE-IT.  All rights reserved.
Copyright (c) 2008-2022 Ivan Maidanski
Copyright (c) 2009 Bradley Smith
Copyright (c) 2009 by Takashi Yoshii.  All rights reserved.


Our intent is to make it easy to use libatomic_ops, in both free and
proprietary software.  Hence most of code (core library) that we expect to
be linked into a client application is covered by a MIT or MIT-style license.

However, a few library routines (the gpl extension library) are covered by
the GNU General Public License.  These are put into a separate library,
libatomic_ops_gpl.a file.

Most of the test code is covered by the GNU General Public License too.


The low-level (core) part of the library (libatomic_ops.a) is mostly covered
by the MIT license:

----------------------------------------

Copyright (c) ...

Permission is hereby granted, free of charge, to any person obtaining a copy
of this software and associated documentation files (the "Software"), to deal
in the Software without restriction, including without limitation the rights
to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
copies of the Software, and to permit persons to whom the Software is
furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in
all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
SOFTWARE.

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Some files in the atomic_ops/sysdeps directory (part of core library) were
inherited in part from the Boehm-Demers-Weiser conservative garbage collector,
and are covered by its license, which is similar in spirit to MIT license:

--------------------------------

Copyright (c) ...

THIS MATERIAL IS PROVIDED AS IS, WITH ABSOLUTELY NO WARRANTY EXPRESSED
OR IMPLIED.  ANY USE IS AT YOUR OWN RISK.

Permission is hereby granted to use or copy this program
for any purpose, provided the above notices are retained on all copies.
Permission to modify the code and to distribute modified code is granted,
provided the above notices are retained, and a notice that the code was
modified is included with the above copyright notice.

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A few files are covered by the GNU General Public License.  (See file
"COPYING".)  This applies only to the test code and the atomic_ops_gpl
portion of the library.  Thus, atomic_ops_gpl should generally not be
linked into proprietary code.  (This distinction was motivated by patent
considerations.)