path: root/tests/tmul_2exp.c

/* Test file for mpfr_{mul,div}_2{ui,si}.

Copyright 1999, 2001-2004, 2006-2021 Free Software Foundation, Inc.
Contributed by the AriC and Caramba 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
https://www.gnu.org/licenses/ or write to the Free Software Foundation, Inc.,
51 Franklin St, Fifth Floor, Boston, MA 02110-1301, USA. */

#include "mpfr-test.h"

static const char * const val[] = {
  "1.0001@100","4.0004000000000@102", "4.0004000000000@97",
  "1.ABF012345@-100","6.afc048d140000@-98","6.afc048d140000@-103",
  "F.FFFFFFFFF@10000","3.fffffffffc000@10003","3.fffffffffc000@9998",
  "1.23456789ABCDEF@42","4.8d159e26af37c@44","4.8d159e26af37c@39",
  "17@42","5.c000000000000@45","5.c000000000000@40",
  "42@-17","1.0800000000000@-13","1.0800000000000@-18"
};

static int
test_mul (int i, int div, mpfr_ptr y, mpfr_srcptr x,
          unsigned long int n, mpfr_rnd_t r)
{
  return
    i == 0 ? (div ? mpfr_div_2ui : mpfr_mul_2ui) (y, x, n, r) :
    i == 1 ? (div ? mpfr_div_2si : mpfr_mul_2si) (y, x, n, r) :
    i == 2 ? (div ? mpfr_mul_2si : mpfr_div_2si) (y, x, -n, r) :
    (exit (1), 0);
}

static void
underflow (mpfr_exp_t e)
{
  mpfr_t x, y, z1, z2;
  mpfr_exp_t emin;
  int i, k, s;
  int prec;
  int rnd;
  int div;
  int inex1, inex2;
  unsigned int flags1, flags2;

  /* Test mul_2si(x, e - k), div_2si(x, k - e) and div_2ui(x, k - e) with
   * emin = e, x = s * (1 + i/16), i in { -1, 0, 1 }, s in { -1, 1 }, and
   * k = 1 to 4, by comparing the result with the one of a simple division.
   */
  emin = mpfr_get_emin ();
  set_emin (e);
  mpfr_inits2 (8, x, y, (mpfr_ptr) 0);
  for (i = 15; i <= 17; i++)
    for (s = 1; s >= -1; s -= 2)
      {
        inex1 = mpfr_set_si_2exp (x, s * i, -4, MPFR_RNDN);
        MPFR_ASSERTN (inex1 == 0);
        for (prec = 6; prec >= 3; prec -= 3)
          {
            mpfr_inits2 (prec, z1, z2, (mpfr_ptr) 0);
            RND_LOOP_NO_RNDF (rnd)
              for (k = 1; k <= 4; k++)
                {
                  /* The following one is assumed to be correct. */
                  inex1 = mpfr_mul_2si (y, x, e, MPFR_RNDN);
                  MPFR_ASSERTN (inex1 == 0);
                  inex1 = mpfr_set_ui (z1, 1 << k, MPFR_RNDN);
                  MPFR_ASSERTN (inex1 == 0);
                  mpfr_clear_flags ();
                  /* Do not use mpfr_div_ui to avoid the optimization
                     by mpfr_div_2si. */
                  inex1 = mpfr_div (z1, y, z1, (mpfr_rnd_t) rnd);
                  flags1 = __gmpfr_flags;

                  for (div = 0; div <= 2; div++)
                    {
                      mpfr_clear_flags ();
                      inex2 =
                        div == 0 ?
                        mpfr_mul_2si (z2, x, e - k, (mpfr_rnd_t) rnd) :
                        div == 1 ?
                        mpfr_div_2si (z2, x, k - e, (mpfr_rnd_t) rnd) :
                        mpfr_div_2ui (z2, x, k - e, (mpfr_rnd_t) rnd);
                      flags2 = __gmpfr_flags;
                      if (flags1 == flags2 && SAME_SIGN (inex1, inex2) &&
                          mpfr_equal_p (z1, z2))
                        continue;
                      printf ("Error in underflow(");
                      if (e == MPFR_EMIN_MIN)
                        printf ("MPFR_EMIN_MIN");
                      else if (e == emin)
                        printf ("default emin");
                      else
                        printf ("%" MPFR_EXP_FSPEC "d", (mpfr_eexp_t) e);
                      printf (") with mpfr_%s,\nx = %d/16, prec = %d, k = %d,"
                              " %s\n", div == 0 ? "mul_2si" : div == 1 ?
                              "div_2si" : "div_2ui", s * i, prec, k,
                              mpfr_print_rnd_mode ((mpfr_rnd_t) rnd));
                      printf ("Expected ");
                      mpfr_out_str (stdout, 16, 0, z1, MPFR_RNDN);
                      printf (", inex = %d, flags = %u\n",
                              VSIGN (inex1), flags1);
                      printf ("Got      ");
                      mpfr_out_str (stdout, 16, 0, z2, MPFR_RNDN);
                      printf (", inex = %d, flags = %u\n",
                              VSIGN (inex2), flags2);
                      exit (1);
                    }  /* div */
                }  /* k */
            mpfr_clears (z1, z2, (mpfr_ptr) 0);
          }  /* prec */
      }  /* i */
  mpfr_clears (x, y, (mpfr_ptr) 0);
  set_emin (emin);
}

static void
underflow0 (void)
{
  underflow (-256);
  if (mpfr_get_emin () != MPFR_EMIN_MIN)
    underflow (mpfr_get_emin ());
  underflow (MPFR_EMIN_MIN);
}

static void
large (mpfr_exp_t e)
{
  mpfr_t x, y, z;
  mpfr_exp_t emax;
  int inex;
  unsigned int flags;

  emax = mpfr_get_emax ();
  set_emax (e);
  mpfr_init2 (x, 8);
  mpfr_init2 (y, 8);
  mpfr_init2 (z, 4);

  mpfr_set_inf (x, 1);
  mpfr_nextbelow (x);

  mpfr_mul_2si (y, x, -1, MPFR_RNDU);
  mpfr_prec_round (y, 4, MPFR_RNDU);

  mpfr_clear_flags ();
  inex = mpfr_mul_2si (z, x, -1, MPFR_RNDU);
  flags = __gmpfr_flags;

  if (inex <= 0 || flags != MPFR_FLAGS_INEXACT || ! mpfr_equal_p (y, z))
    {
      printf ("Error in large(");
      if (e == MPFR_EMAX_MAX)
        printf ("MPFR_EMAX_MAX");
      else if (e == emax)
        printf ("default emax");
      else
        printf ("%" MPFR_EXP_FSPEC "d", (mpfr_eexp_t) e);
      printf (") for mpfr_mul_2si\n");
      printf ("Expected inex > 0, flags = %u,\n         y = ",
              (unsigned int) MPFR_FLAGS_INEXACT);
      mpfr_dump (y);
      printf ("Got      inex = %d, flags = %u,\n         y = ",
              inex, flags);
      mpfr_dump (z);
      exit (1);
    }

  mpfr_clear_flags ();
  inex = mpfr_div_2si (z, x, 1, MPFR_RNDU);
  flags = __gmpfr_flags;

  if (inex <= 0 || flags != MPFR_FLAGS_INEXACT || ! mpfr_equal_p (y, z))
    {
      printf ("Error in large(");
      if (e == MPFR_EMAX_MAX)
        printf ("MPFR_EMAX_MAX");
      else if (e == emax)
        printf ("default emax");
      else
        printf ("%" MPFR_EXP_FSPEC "d", (mpfr_eexp_t) e);
      printf (") for mpfr_div_2si\n");
      printf ("Expected inex > 0, flags = %u,\n         y = ",
              (unsigned int) MPFR_FLAGS_INEXACT);
      mpfr_dump (y);
      printf ("Got      inex = %d, flags = %u,\n         y = ",
              inex, flags);
      mpfr_dump (z);
      exit (1);
    }

  mpfr_clear_flags ();
  inex = mpfr_div_2ui (z, x, 1, MPFR_RNDU);
  flags = __gmpfr_flags;

  if (inex <= 0 || flags != MPFR_FLAGS_INEXACT || ! mpfr_equal_p (y, z))
    {
      printf ("Error in large(");
      if (e == MPFR_EMAX_MAX)
        printf ("MPFR_EMAX_MAX");
      else if (e == emax)
        printf ("default emax");
      else
        printf ("%" MPFR_EXP_FSPEC "d", (mpfr_eexp_t) e);
      printf (") for mpfr_div_2ui\n");
      printf ("Expected inex > 0, flags = %u,\n         y = ",
              (unsigned int) MPFR_FLAGS_INEXACT);
      mpfr_dump (y);
      printf ("Got      inex = %d, flags = %u,\n         y = ",
              inex, flags);
      mpfr_dump (z);
      exit (1);
    }

  mpfr_clears (x, y, z, (mpfr_ptr) 0);
  set_emax (emax);
}

static void
large0 (void)
{
  mpfr_exp_t emin;

  emin = mpfr_get_emin ();

  while (1)
    {
      large (256);
      if (mpfr_get_emax () != MPFR_EMAX_MAX)
        large (mpfr_get_emax ());
      large (MPFR_EMAX_MAX);
      if (mpfr_get_emin () == MPFR_EMIN_MIN)
        break;
      /* Redo the test with __gmpfr_emin set to MPFR_EMIN_MIN, which can
         be useful to trigger integer overflows as in div_2ui.c r12272. */
      set_emin (MPFR_EMIN_MIN);
    }

  set_emin (emin);
}

/* Cases where the function overflows on n = 0 when rounding is like
   away from zero. */
static void
overflow0 (mpfr_exp_t emax)
{
  mpfr_exp_t old_emax;
  mpfr_t x, y1, y2;
  int neg, r, op;
  static const char *sop[4] = { "mul_2ui", "mul_2si", "div_2ui", "div_2si" };

  old_emax = mpfr_get_emax ();
  set_emax (emax);

  mpfr_init2 (x, 8);
  mpfr_inits2 (6, y1, y2, (mpfr_ptr) 0);

  mpfr_set_inf (x, 1);
  mpfr_nextbelow (x);

  for (neg = 0; neg <= 1; neg++)
    {
      RND_LOOP_NO_RNDF (r)
        {
          int inex1, inex2;
          mpfr_flags_t flags1, flags2;

          /* Even if there isn't an overflow (rounding ~ toward zero),
             the result is the same as the one of an overflow. */
          inex1 = mpfr_overflow (y1, (mpfr_rnd_t) r, neg ? -1 : 1);
          flags1 = MPFR_FLAGS_INEXACT;
          if (mpfr_inf_p (y1))
            flags1 |= MPFR_FLAGS_OVERFLOW;
          for (op = 0; op < 4; op++)
            {
              mpfr_clear_flags ();
              inex2 =
                op == 0 ? mpfr_mul_2ui (y2, x, 0, (mpfr_rnd_t) r) :
                op == 1 ? mpfr_mul_2si (y2, x, 0, (mpfr_rnd_t) r) :
                op == 2 ? mpfr_div_2ui (y2, x, 0, (mpfr_rnd_t) r) :
                op == 3 ? mpfr_div_2si (y2, x, 0, (mpfr_rnd_t) r) :
                (MPFR_ASSERTN (0), 0);
              flags2 = __gmpfr_flags;
              if (!(mpfr_equal_p (y1, y2) &&
                    SAME_SIGN (inex1, inex2) &&
                    flags1 == flags2))
                {
                  printf ("Error in overflow0 for %s, mpfr_%s, emax = %"
                          MPFR_EXP_FSPEC "d,\nx = ",
                          mpfr_print_rnd_mode ((mpfr_rnd_t) r), sop[op],
                          (mpfr_eexp_t) emax);
                  mpfr_dump (x);
                  printf ("Expected ");
                  mpfr_dump (y1);
                  printf ("  with inex = %d, flags =", inex1);
                  flags_out (flags1);
                  printf ("Got      ");
                  mpfr_dump (y2);
                  printf ("  with inex = %d, flags =", inex2);
                  flags_out (flags2);
                  exit (1);
                }
            }
        }
      mpfr_neg (x, x, MPFR_RNDN);
    }

  mpfr_clears (x, y1, y2, (mpfr_ptr) 0);
  set_emax (old_emax);
}

static void
coverage_div_2ui (void)
{
  mpfr_t x, y;

  mpfr_init2 (x, 2);
  mpfr_init2 (y, 2);
  mpfr_set_ui_2exp (x, 1, mpfr_get_emax () - 1, MPFR_RNDN);
  mpfr_div_2ui (y, x, (unsigned long) LONG_MAX + 1, MPFR_RNDN);
  MPFR_ASSERTN(mpfr_zero_p (y));
  MPFR_ASSERTN(mpfr_signbit (y) == 0);
  mpfr_clear (x);
  mpfr_clear (y);
}

int
main (int argc, char *argv[])
{
  mpfr_t w,z;
  unsigned long k;
  int i;

  tests_start_mpfr ();

  coverage_div_2ui ();
  mpfr_inits2 (53, w, z, (mpfr_ptr) 0);

  for (i = 0; i < 3; i++)
    {
      mpfr_set_inf (w, 1);
      test_mul (i, 0, w, w, 10, MPFR_RNDZ);
      if (!MPFR_IS_INF(w))
        {
          printf ("Result is not Inf (i = %d)\n", i);
          exit (1);
        }

      mpfr_set_nan (w);
      test_mul (i, 0, w, w, 10, MPFR_RNDZ);
      if (!MPFR_IS_NAN(w))
        {
          printf ("Result is not NaN (i = %d)\n", i);
          exit (1);
        }

      for (k = 0 ; k < numberof(val) ; k+=3)
        {
          mpfr_set_str (w, val[k], 16, MPFR_RNDN);
          test_mul (i, 0, z, w, 10, MPFR_RNDZ);
          if (mpfr_cmp_str (z, val[k+1], 16, MPFR_RNDN))
            {
              printf ("ERROR for x * 2^n (i = %d) for %s\n", i, val[k]);
              printf ("Expected: %s\n"
                      "Got     : ", val[k+1]);
              mpfr_out_str (stdout, 16, 0, z, MPFR_RNDN);
              putchar ('\n');
              exit (1);
            }
          test_mul (i, 1, z, w, 10, MPFR_RNDZ);
          if (mpfr_cmp_str (z, val[k+2], 16, MPFR_RNDN))
            {
              printf ("ERROR for x / 2^n (i = %d) for %s\n", i, val[k]);
              printf ("Expected: %s\n"
                      "Got     : ", val[k+2]);
              mpfr_out_str (stdout, 16, 0, z, MPFR_RNDN);
              putchar ('\n');
              exit (1);
            }
        }

      mpfr_set_inf (w, 1);
      mpfr_nextbelow (w);
      test_mul (i, 0, w, w, 1, MPFR_RNDN);
      if (!mpfr_inf_p (w))
        {
          printf ("Overflow error (i = %d)!\n", i);
          exit (1);
        }
      mpfr_set_ui (w, 0, MPFR_RNDN);
      mpfr_nextabove (w);
      test_mul (i, 1, w, w, 1, MPFR_RNDN);
      if (mpfr_cmp_ui (w, 0))
        {
          printf ("Underflow error (i = %d)!\n", i);
          exit (1);
        }
    }

  if (MPFR_EXP_MAX >= LONG_MAX/2 && MPFR_EXP_MIN <= LONG_MAX/2-LONG_MAX-1)
    {
      unsigned long lmp1 = (unsigned long) LONG_MAX + 1;

      mpfr_set_ui (w, 1, MPFR_RNDN);
      mpfr_mul_2ui (w, w, LONG_MAX/2, MPFR_RNDZ);
      mpfr_div_2ui (w, w, lmp1, MPFR_RNDZ);
      mpfr_mul_2ui (w, w, lmp1 - LONG_MAX/2, MPFR_RNDZ);
      if (!mpfr_cmp_ui (w, 1))
        {
          printf ("Underflow LONG_MAX error!\n");
          exit (1);
        }
    }

  mpfr_clears (w, z, (mpfr_ptr) 0);

  underflow0 ();
  large0 ();

  if (mpfr_get_emax () != MPFR_EMAX_MAX)
    overflow0 (mpfr_get_emax ());
  overflow0 (MPFR_EMAX_MAX);
  overflow0 (-1);

  tests_end_mpfr ();
  return 0;
}