/* 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(__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_ */