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/* Copyright (c) 2013, Ben Noordhuis <info@bnoordhuis.nl>
*
* Permission to use, copy, modify, and/or distribute this software for any
* purpose with or without fee is hereby granted, provided that the above
* copyright notice and this permission notice appear in all copies.
*
* THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
* WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
* MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
* ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
* WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
* ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
* OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
*/
#ifndef UV_ATOMIC_OPS_H_
#define UV_ATOMIC_OPS_H_
#include "internal.h" /* UV_UNUSED */
#if defined(__SUNPRO_C) || defined(__SUNPRO_CC)
#include <atomic.h>
#endif
UV_UNUSED(static int cmpxchgi(int* ptr, int oldval, int newval));
UV_UNUSED(static void cpu_relax(void));
/* Prefer hand-rolled assembly over the gcc builtins because the latter also
* issue full memory barriers.
*/
UV_UNUSED(static int cmpxchgi(int* ptr, int oldval, int newval)) {
#if defined(__i386__) || defined(__x86_64__)
int out;
__asm__ __volatile__ ("lock; cmpxchg %2, %1;"
: "=a" (out), "+m" (*(volatile int*) ptr)
: "r" (newval), "0" (oldval)
: "memory");
return out;
#elif defined(_AIX) && defined(__ibmxl__)
/* FIXME: This is not actually atomic but XLClang 16.1 for AIX
does not provide __sync_val_compare_and_swap or an equivalent.
Its documentation suggests using C++11 atomics but this is C. */
__compare_and_swap((volatile int*)ptr, &oldval, newval);
return oldval;
#elif defined(__MVS__)
unsigned int op4;
if (__plo_CSST(ptr, (unsigned int*) &oldval, newval,
(unsigned int*) ptr, *ptr, &op4))
return oldval;
else
return op4;
#elif defined(__SUNPRO_C) || defined(__SUNPRO_CC)
return atomic_cas_uint((uint_t *)ptr, (uint_t)oldval, (uint_t)newval);
#else
return __sync_val_compare_and_swap(ptr, oldval, newval);
#endif
}
UV_UNUSED(static void cpu_relax(void)) {
#if defined(__i386__) || defined(__x86_64__)
__asm__ __volatile__ ("rep; nop"); /* a.k.a. PAUSE */
#elif (defined(__arm__) && __ARM_ARCH >= 7) || defined(__aarch64__)
__asm__ volatile("yield");
#endif
}
#endif /* UV_ATOMIC_OPS_H_ */
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