/* [Description]

Copyright 2010, 2011 Free Software Foundation, Inc.
Contributed by the Arenaire and Caramel projects, INRIA.

This file is part of the GNU MPFR Library.

The GNU MPFR 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 3 of the License, or (at your
option) any later version.

The GNU MPFR 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 MPFR Library; see the file COPYING.LESSER.  If not, see
http://www.gnu.org/licenses/ or write to the Free Software Foundation, Inc.,
51 Franklin St, Fifth Floor, Boston, MA 02110-1301, USA. */

#include <stdlib.h>
#include <time.h>

#define MPFR_NEED_LONGLONG_H
#include "mpfr-impl.h"

#undef _PROTO
#define _PROTO __GMP_PROTO
#include "speed.h"

/* Let f be a function for which we have several implementations f1, f2... */
/* We wish to have a quick overview of which implementation is the best    */
/* in function of the point x where f(x) is computed and of the prectision */
/* prec requested by the user.                                             */
/* This is performed by drawing a 2D graphic with color indicating which   */
/* method is the best.                                                     */
/* For building this graphic, the following structur is used (see the core */
/* of generate_2D_sample for an explanation of each field.                 */
struct speed_params2D
{
  /* x-window: [min_x, max_x] or [2^min_x, 2^max_x]                        */
  /*           or [-2^(max_x), -2^(min_x)] U [2^min_x, 2^max_x]            */
  /* depending on the value of logarithmic_scale_x                         */
  double min_x;
  double max_x;

  /* prec-window: [min_prec, max_prec] */
  mpfr_prec_t min_prec;
  mpfr_prec_t max_prec;

  /* number of sample points for the x-axis and the prec-axis */
  int nb_points_x;
  int nb_points_prec;

  /* should the sample points be logarithmically scaled or not */
  int logarithmic_scale_x;
  int logarithmic_scale_prec;

  /* list of functions g1, g2... measuring the execution time of f1, f2...  */
  /* when given a point x and a precision prec stored in s.                 */
  /* We use s->xp to store the significant of x, s->r to store its exponent */
  /* s->align_xp to store its sign, and s->size to store prec.              */
  double (**speed_funcs) (struct speed_params *s);
};

/* Given an array t of nb_functions double indicating the timings of several */
/* implementations, return i, such that t[i] is the best timing.             */
int
find_best (double *t, int nb_functions)
{
  int i, ibest;
  double best;

  if (nb_functions<=0)
    {
      fprintf (stderr, "There is no function\n");
      abort ();
    }

  ibest = 0;
  best = t[0];
  for (i=1; i<nb_functions; i++)
    {
      if (t[i]<best)
        {
          best = t[i];
          ibest = i;
        }
    }

  return ibest;
}

void generate_2D_sample (FILE *output, struct speed_params2D param)
{
  mpfr_t temp;
  double incr_prec;
  mpfr_t incr_x;
  mpfr_t x, x2;
  double prec;
  struct speed_params s;
  int i;
  int test;
  int nb_functions;
  double *t; /* store the timing of each implementation */

  /* We first determine how many implementations we have */
  nb_functions = 0;
  while (param.speed_funcs[nb_functions] != NULL)
    nb_functions++;

  t = malloc (nb_functions * sizeof (double));
  if (t == NULL)
    {
      fprintf (stderr, "Can't allocate memory.\n");
      abort ();
    }


  mpfr_init2 (temp, MPFR_SMALL_PRECISION);

  /* The precision is sampled from min_prec to max_prec with        */
  /* approximately nb_points_prec points. If logarithmic_scale_prec */
  /* is true, the precision is multiplied by incr_prec at each      */
  /* step. Otherwise, incr_prec is added at each step.              */
  if (param.logarithmic_scale_prec)
    {
      mpfr_set_ui (temp, (unsigned long int)param.max_prec, MPFR_RNDU);
      mpfr_div_ui (temp, temp, (unsigned long int)param.min_prec, MPFR_RNDU);
      mpfr_root (temp, temp,
                 (unsigned long int)param.nb_points_prec, MPFR_RNDU);
      incr_prec = mpfr_get_d (temp, MPFR_RNDU);
    }
  else
    {
      incr_prec = (double)param.max_prec - (double)param.min_prec;
      incr_prec = incr_prec/((double)param.nb_points_prec);
    }

  /* The points x are sampled according to the following rule:             */
  /* If logarithmic_scale_x = 0:                                           */
  /*    nb_points_x points are equally distributed between min_x and max_x */
  /* If logarithmic_scale_x = 1:                                           */
  /*    nb_points_x points are sampled from 2^(min_x) to 2^(max_x). At     */
  /*    each step, the current point is multiplied by incr_x.              */
  /* If logarithmic_scale_x = -1:                                          */
  /*    nb_points_x/2 points are sampled from -2^(max_x) to -2^(min_x)     */
  /*    (at each step, the current point is divided by incr_x);  and       */
  /*    nb_points_x/2 points are sampled from 2^(min_x) to 2^(max_x)       */
  /*    (at each step, the current point is multiplied by incr_x).         */
  mpfr_init2 (incr_x, param.max_prec);
  if (param.logarithmic_scale_x == 0)
    {
      mpfr_set_d (incr_x,
                  (param.max_x - param.min_x)/(double)param.nb_points_x,
                  MPFR_RNDU);
    }
  else if (param.logarithmic_scale_x == -1)
    {
      mpfr_set_d (incr_x,
                  2.*(param.max_x - param.min_x)/(double)param.nb_points_x,
                  MPFR_RNDU);
      mpfr_exp2 (incr_x, incr_x, MPFR_RNDU);
    }
  else
    { /* other values of param.logarithmic_scale_x are considered as 1 */
      mpfr_set_d (incr_x,
                  (param.max_x - param.min_x)/(double)param.nb_points_x,
                  MPFR_RNDU);
      mpfr_exp2 (incr_x, incr_x, MPFR_RNDU);
    }

  /* Main loop */
  mpfr_init2 (x, param.max_prec);
  mpfr_init2 (x2, param.max_prec);
  prec = (double)param.min_prec;
  while (prec <= param.max_prec)
    {
      printf ("prec = %d\n", (int)prec);
      if (param.logarithmic_scale_x == 0)
        mpfr_set_d (temp, param.min_x, MPFR_RNDU);
      else if (param.logarithmic_scale_x == -1)
        {
          mpfr_set_d (temp, param.max_x, MPFR_RNDD);
          mpfr_exp2 (temp, temp, MPFR_RNDD);
          mpfr_neg (temp, temp, MPFR_RNDU);
        }
      else
        {
          mpfr_set_d (temp, param.min_x, MPFR_RNDD);
          mpfr_exp2 (temp, temp, MPFR_RNDD);
        }

      /* We perturb x a little bit, in order to avoid trailing zeros that */
      /* might change the behavior of algorithms.                         */
      mpfr_const_pi (x, MPFR_RNDN);
      mpfr_div_2ui (x, x, 7, MPFR_RNDN);
      mpfr_add_ui (x, x, 1, MPFR_RNDN);
      mpfr_mul (x, x, temp, MPFR_RNDN);

      test = 1;
      while (test)
        {
          mpfr_fprintf (output, "%e\t", mpfr_get_d (x, MPFR_RNDN));
          mpfr_fprintf (output, "%Pu\t", (mpfr_prec_t)prec);

          s.r = (mp_limb_t)mpfr_get_exp (x);
          s.size = (mpfr_prec_t)prec;
          s.align_xp = (mpfr_sgn (x) > 0)?1:2;
          mpfr_set_prec (x2, (mpfr_prec_t)prec);
          mpfr_set (x2, x, MPFR_RNDU);
          s.xp = x2->_mpfr_d;

          for (i=0; i<nb_functions; i++)
            {
              t[i] = speed_measure (param.speed_funcs[i], &s);
              mpfr_fprintf (output, "%e\t", t[i]);
            }
          fprintf (output, "%d\n", 1 + find_best (t, nb_functions));

          if (param.logarithmic_scale_x == 0)
            {
              mpfr_add (x, x, incr_x, MPFR_RNDU);
              if (mpfr_cmp_d (x, param.max_x) > 0)
                test=0;
            }
          else
            {
              if (mpfr_sgn (x) < 0 )
                { /* if x<0, it means that logarithmic_scale_x=-1 */
                  mpfr_div (x, x, incr_x, MPFR_RNDU);
                  mpfr_abs (temp, x, MPFR_RNDD);
                  mpfr_log2 (temp, temp, MPFR_RNDD);
                  if (mpfr_cmp_d (temp, param.min_x) < 0)
                    mpfr_neg (x, x, MPFR_RNDN);
                }
              else
                {
                  mpfr_mul (x, x, incr_x, MPFR_RNDU);
                  mpfr_set (temp, x, MPFR_RNDD);
                  mpfr_log2 (temp, temp, MPFR_RNDD);
                  if (mpfr_cmp_d (temp, param.max_x) > 0)
                    test=0;
                }
            }
        }

      prec = ( (param.logarithmic_scale_prec) ? (prec * incr_prec)
               : (prec + incr_prec) );
      fprintf (output, "\n");
    }

  free (t);
  mpfr_clear (incr_x);
  mpfr_clear (x);
  mpfr_clear (x2);
  mpfr_clear (temp);

  return;
}

#define SPEED_MPFR_FUNC_2D(mean_func)                   \
  do                                                    \
    {                                                   \
      double t;                                         \
      unsigned i;                                       \
      mpfr_t w, x;                                      \
      mp_size_t size;                                   \
                                                        \
      SPEED_RESTRICT_COND (s->size >= MPFR_PREC_MIN);   \
      SPEED_RESTRICT_COND (s->size <= MPFR_PREC_MAX);   \
                                                        \
      size = (s->size-1)/GMP_NUMB_BITS+1;               \
      s->xp[size-1] |= MPFR_LIMB_HIGHBIT;               \
      MPFR_TMP_INIT1 (s->xp, x, s->size);               \
      MPFR_SET_EXP (x, (mpfr_exp_t) s->r);              \
      if (s->align_xp == 2) MPFR_SET_NEG (x);           \
                                                        \
      mpfr_init2 (w, s->size);                          \
      speed_starttime ();                               \
      i = s->reps;                                      \
                                                        \
      do                                                \
        mean_func (w, x, MPFR_RNDN);                    \
      while (--i != 0);                                 \
      t = speed_endtime ();                             \
                                                        \
      mpfr_clear (w);                                   \
      return t;                                         \
    }                                                   \
  while (0)

mpfr_prec_t mpfr_exp_2_threshold;
mpfr_prec_t old_threshold = MPFR_EXP_2_THRESHOLD;
#undef  MPFR_EXP_2_THRESHOLD
#define MPFR_EXP_2_THRESHOLD mpfr_exp_2_threshold
#include "exp_2.c"

double
timing_exp1 (struct speed_params *s)
{
  mpfr_exp_2_threshold = s->size+1;
  SPEED_MPFR_FUNC_2D (mpfr_exp_2);
}

double
timing_exp2 (struct speed_params *s)
{
  mpfr_exp_2_threshold = s->size-1;
  SPEED_MPFR_FUNC_2D (mpfr_exp_2);
}

double
timing_exp3 (struct speed_params *s)
{
  SPEED_MPFR_FUNC_2D (mpfr_exp_3);
}


#include "ai.c"
double
timing_ai1 (struct speed_params *s)
{
  SPEED_MPFR_FUNC_2D (mpfr_ai1);
}

double
timing_ai2 (struct speed_params *s)
{
  SPEED_MPFR_FUNC_2D (mpfr_ai2);
}

/* These functions are for testing purpose only */
/* They are used to draw which method is actually used */
double
virtual_timing_ai1 (struct speed_params *s)
{
  double t;
  unsigned i;
  mpfr_t w, x;
  mp_size_t size;
  mpfr_t temp1, temp2;

  SPEED_RESTRICT_COND (s->size >= MPFR_PREC_MIN);
  SPEED_RESTRICT_COND (s->size <= MPFR_PREC_MAX);

  size = (s->size-1)/GMP_NUMB_BITS+1;
  s->xp[size-1] |= MPFR_LIMB_HIGHBIT;
  MPFR_TMP_INIT1 (s->xp, x, s->size);
  MPFR_SET_EXP (x, (mpfr_exp_t) s->r);
  if (s->align_xp == 2) MPFR_SET_NEG (x);

  mpfr_init2 (w, s->size);
  speed_starttime ();
  i = s->reps;

  mpfr_init2 (temp1, MPFR_SMALL_PRECISION);
  mpfr_init2 (temp2, MPFR_SMALL_PRECISION);

  mpfr_set (temp1, x, MPFR_SMALL_PRECISION);
  mpfr_set_si (temp2, MPFR_AI_THRESHOLD2, MPFR_RNDN);
  mpfr_mul_ui (temp2, temp2, (unsigned int)MPFR_PREC (w), MPFR_RNDN);

  if (MPFR_IS_NEG (x))
      mpfr_mul_si (temp1, temp1, MPFR_AI_THRESHOLD1, MPFR_RNDN);
  else
      mpfr_mul_si (temp1, temp1, MPFR_AI_THRESHOLD3, MPFR_RNDN);

  mpfr_add (temp1, temp1, temp2, MPFR_RNDN);

  if (mpfr_cmp_si (temp1, MPFR_AI_SCALE) > 0)
    t = 1000.;
  else
    t = 1.;

  mpfr_clear (temp1);
  mpfr_clear (temp2);

  return t;
}

double
virtual_timing_ai2 (struct speed_params *s)
{
  double t;
  unsigned i;
  mpfr_t w, x;
  mp_size_t size;
  mpfr_t temp1, temp2;

  SPEED_RESTRICT_COND (s->size >= MPFR_PREC_MIN);
  SPEED_RESTRICT_COND (s->size <= MPFR_PREC_MAX);

  size = (s->size-1)/GMP_NUMB_BITS+1;
  s->xp[size-1] |= MPFR_LIMB_HIGHBIT;
  MPFR_TMP_INIT1 (s->xp, x, s->size);
  MPFR_SET_EXP (x, (mpfr_exp_t) s->r);
  if (s->align_xp == 2) MPFR_SET_NEG (x);

  mpfr_init2 (w, s->size);
  speed_starttime ();
  i = s->reps;

  mpfr_init2 (temp1, MPFR_SMALL_PRECISION);
  mpfr_init2 (temp2, MPFR_SMALL_PRECISION);

  mpfr_set (temp1, x, MPFR_SMALL_PRECISION);
  mpfr_set_si (temp2, MPFR_AI_THRESHOLD2, MPFR_RNDN);
  mpfr_mul_ui (temp2, temp2, (unsigned int)MPFR_PREC (w), MPFR_RNDN);

  if (MPFR_IS_NEG (x))
      mpfr_mul_si (temp1, temp1, MPFR_AI_THRESHOLD1, MPFR_RNDN);
  else
      mpfr_mul_si (temp1, temp1, MPFR_AI_THRESHOLD3, MPFR_RNDN);

  mpfr_add (temp1, temp1, temp2, MPFR_RNDN);

  if (mpfr_cmp_si (temp1, MPFR_AI_SCALE) > 0)
    t = 1.;
  else
    t = 1000.;

  mpfr_clear (temp1);
  mpfr_clear (temp2);

  return t;
}

int
main (void)
{
  FILE *output;
  struct speed_params2D param;
  double (*speed_funcs[3]) (struct speed_params *s);

  /* char filename[256] = "virtual_timing_ai.dat"; */
  /* speed_funcs[0] = virtual_timing_ai1; */
  /* speed_funcs[1] = virtual_timing_ai2; */

  char filename[256] = "airy.dat";
  speed_funcs[0] = timing_ai1;
  speed_funcs[1] = timing_ai2;

  speed_funcs[2] = NULL;
  output = fopen (filename, "w");
  if (output == NULL)
    {
      fprintf (stderr, "Can't open file '%s' for writing.\n", filename);
      abort ();
    }
  param.min_x = -80;
  param.max_x = 60;
  param.min_prec = 50;
  param.max_prec = 1500;
  param.nb_points_x = 200;
  param.nb_points_prec = 200;
  param.logarithmic_scale_x  = 0;
  param.logarithmic_scale_prec = 0;
  param.speed_funcs = speed_funcs;

  generate_2D_sample (output, param);

  fclose (output);
  mpfr_free_cache ();
  return 0;
}