/usr/include/atomic_ops/sysdeps/emul_cas.h is in libatomic-ops-dev 7.2~alpha5+cvs20101124-1ubuntu1.
This file is owned by root:root, with mode 0o644.
The actual contents of the file can be viewed below.
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* Copyright (c) 2003 by Hewlett-Packard Company. All rights reserved.
*
* 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.
*/
/*
* Ensure, if at all possible, that AO_compare_and_swap_full() is
* available. The emulation should be brute-force signal-safe, even
* though it actually blocks.
* Including this file will generate an error if AO_compare_and_swap_full()
* cannot be made available.
* This will be included from platform-specific atomic_ops files
* id appropriate, and if AO_FORCE_CAS is defined. It should not be
* included directly, especially since it affects the implementation
* of other atomic update primitives.
* The implementation assumes that only AO_store_XXX and AO_test_and_set_XXX
* variants are defined, and that AO_test_and_set_XXX is not used to
* operate on compare_and_swap locations.
*/
#if !defined(ATOMIC_OPS_H)
# error This file should not be included directly.
#endif
#ifndef AO_HAVE_double_t
# include "standard_ao_double_t.h"
#endif
int AO_compare_and_swap_emulation(volatile AO_t *addr, AO_t old,
AO_t new_val);
int AO_compare_double_and_swap_double_emulation(volatile AO_double_t *addr,
AO_t old_val1, AO_t old_val2,
AO_t new_val1, AO_t new_val2);
void AO_store_full_emulation(volatile AO_t *addr, AO_t val);
#define AO_compare_and_swap_full(addr, old, newval) \
AO_compare_and_swap_emulation(addr, old, newval)
#define AO_HAVE_compare_and_swap_full
#ifndef AO_HAVE_compare_double_and_swap_double
# define AO_compare_double_and_swap_double_full(addr, old1, old2, \
newval1, newval2) \
AO_compare_double_and_swap_double_emulation(addr, old1, old2, \
newval1, newval2)
# define AO_HAVE_compare_double_and_swap_double_full
#endif
#undef AO_store
#undef AO_HAVE_store
#undef AO_store_write
#undef AO_HAVE_store_write
#undef AO_store_release
#undef AO_HAVE_store_release
#undef AO_store_full
#undef AO_HAVE_store_full
#define AO_store_full(addr, val) AO_store_full_emulation(addr, val)
#define AO_HAVE_store_full
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