/* High precision, low overhead timing functions.  powerpc64 version.
   Copyright (C) 2005-2014 Free Software Foundation, Inc.
   This file is part of the GNU C Library.
   Contributed by Ulrich Drepper <drepper@cygnus.com>, 1998.

   The GNU C Library is free software; you can redistribute it and/or
   modify it under the terms of the GNU Lesser General Public
   License as published by the Free Software Foundation; either
   version 2.1 of the License, or (at your option) any later version.

   The GNU C Library 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
   Lesser General Public License for more details.

   You should have received a copy of the GNU Lesser General Public
   License along with the GNU C Library; if not, see
   <http://www.gnu.org/licenses/>.  */

#ifndef _HP_TIMING_H
#define _HP_TIMING_H	1

#include <string.h>
#include <sys/param.h>
#include <_itoa.h>
#include <atomic.h>

/* The macros defined here use the powerpc 64-bit time base register.
   The time base is nominally clocked at 1/8th the CPU clock, but this
   can vary.

   The list of macros we need includes the following:

   - HP_TIMING_AVAIL: test for availability.

   - HP_TIMING_INLINE: this macro is non-zero if the functionality is not
     implemented using function calls but instead uses some inlined code
     which might simply consist of a few assembler instructions.  We have to
     know this since we might want to use the macros here in places where we
     cannot make function calls.

   - hp_timing_t: This is the type for variables used to store the time
     values.

   - HP_TIMING_NOW: place timestamp for current time in variable given as
     parameter.

   - HP_TIMING_DIFF: compute difference between two times and store it
     in a third.  Source and destination might overlap.

   - HP_TIMING_ACCUM_NT: add time difference to another variable, without
     being thread-safe.

   - HP_TIMING_PRINT: write decimal representation of the timing value into
     the given string.  This operation need not be inline even though
     HP_TIMING_INLINE is specified.

*/

/* We always assume having the timestamp register.  */
#define HP_TIMING_AVAIL		(1)

/* We indeed have inlined functions.  */
#define HP_TIMING_INLINE	(1)

/* We use 64bit values for the times.  */
typedef unsigned long long int hp_timing_t;

/* That's quite simple.  Use the `mftb' instruction.  Note that the value
   might not be 100% accurate since there might be some more instructions
   running in this moment.  This could be changed by using a barrier like
   'lwsync' right before the `mftb' instruction.  But we are not interested
   in accurate clock cycles here so we don't do this.  */
#ifdef _ARCH_PWR4
#define HP_TIMING_NOW(Var)	__asm__ __volatile__ ("mfspr %0,268" : "=r" (Var))
#else
#define HP_TIMING_NOW(Var)	__asm__ __volatile__ ("mftb %0" : "=r" (Var))
#endif

/* It's simple arithmetic in 64-bit.  */
#define HP_TIMING_DIFF(Diff, Start, End)	(Diff) = ((End) - (Start))

#define HP_TIMING_ACCUM_NT(Sum, Diff)	(Sum) += (Diff)

/* Print the time value.  */
#define HP_TIMING_PRINT(Buf, Len, Val) \
  do {									      \
    char __buf[20];							      \
    char *__cp = _itoa (Val, __buf + sizeof (__buf), 10, 0);		      \
    size_t __len = (Len);						      \
    char *__dest = (Buf);						      \
    while (__len-- > 0 && __cp < __buf + sizeof (__buf))		      \
      *__dest++ = *__cp++;						      \
    memcpy (__dest, " ticks", MIN (__len, sizeof (" ticks")));  \
  } while (0)

#endif	/* hp-timing.h */