#ifndef MY_CPU_INCLUDED
#define MY_CPU_INCLUDED
/* Copyright (c) 2013, MariaDB foundation Ab and SkySQL

   This program is free software; you can redistribute it and/or modify
   it under the terms of the GNU General Public License as published by
   the Free Software Foundation; version 2 of the License.

   This program is distributed in the hope that it will be useful,
   but WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
   GNU General Public License for more details.

   You should have received a copy of the GNU General Public License
   along with this program; if not, write to the Free Software
   Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02111-1301  USA
*/

/* instructions for specific cpu's */

/*
  Macros for adjusting thread priority (hardware multi-threading)
  The defines are the same ones used by the linux kernel
*/

#ifdef _ARCH_PWR8
#include <sys/platform/ppc.h>
/* Very low priority */
#define HMT_very_low() __ppc_set_ppr_very_low()
/* Low priority */
#define HMT_low() __ppc_set_ppr_low()
/* Medium low priority */
#define HMT_medium_low() __ppc_set_ppr_med_low()
/* Medium priority */
#define HMT_medium() __ppc_set_ppr_med()
/* Medium high priority */
#define HMT_medium_high() __ppc_set_ppr_med_high()
/* High priority */
#define HMT_high() asm volatile("or 3,3,3")
#else
#define HMT_very_low()
#define HMT_low()
#define HMT_medium_low()
#define HMT_medium()
#define HMT_medium_high()
#define HMT_high()
#endif


static inline void MY_RELAX_CPU(void)
{
#ifdef HAVE_PAUSE_INSTRUCTION
  /*
    According to the gcc info page, asm volatile means that the
    instruction has important side-effects and must not be removed.
    Also asm volatile may trigger a memory barrier (spilling all registers
    to memory).
  */
#ifdef __SUNPRO_CC
  asm ("pause" );
#else
  __asm__ __volatile__ ("pause");
#endif

#elif defined(HAVE_FAKE_PAUSE_INSTRUCTION)
  __asm__ __volatile__ ("rep; nop");
#elif defined _WIN32
  /*
    In the Win32 API, the x86 PAUSE instruction is executed by calling
    the YieldProcessor macro defined in WinNT.h. It is a CPU architecture-
    independent way by using YieldProcessor.
  */
  YieldProcessor();
#elif defined(_ARCH_PWR8)
  __ppc_get_timebase();
#else
  int32 var, oldval = 0;
  my_atomic_cas32_strong_explicit(&var, &oldval, 1, MY_MEMORY_ORDER_RELAXED,
                                  MY_MEMORY_ORDER_RELAXED);
#endif
}


/*
  LF_BACKOFF should be used to improve performance on hyperthreaded CPUs. Intel
  recommends to use it in spin loops also on non-HT machines to reduce power
  consumption (see e.g http://softwarecommunity.intel.com/articles/eng/2004.htm)

  Running benchmarks for spinlocks implemented with InterlockedCompareExchange
  and YieldProcessor shows that much better performance is achieved by calling
  YieldProcessor in a loop - that is, yielding longer. On Intel boxes setting
  loop count in the range 200-300 brought best results.
*/

static inline int LF_BACKOFF(void)
{
  int i;
  for (i= 0; i < 200; i++)
    MY_RELAX_CPU();
  return 1;
}
#endif
