/* Test mpf_sub.

Copyright 1996, 2001, 2004 Free Software Foundation, Inc.

This file is part of the GNU MP Library.

The GNU MP 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 MP 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 MP Library; see the file COPYING.LIB.  If not, write to
the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston,
MA 02110-1301, USA. */

#include <stdio.h>
#include <stdlib.h>

#include "gmp.h"
#include "gmp-impl.h"
#include "tests.h"

#ifndef SIZE
#define SIZE 16
#endif

void
check_rand (int argc, char **argv)
{
  mp_size_t size;
  mp_exp_t exp;
  int reps = 20000;
  int i;
  mpf_t u, v, w, wref;
  mp_size_t bprec = 100;
  mpf_t rerr, max_rerr, limit_rerr;

  if (argc > 1)
    {
      reps = strtol (argv[1], 0, 0);
      if (argc > 2)
	bprec = strtol (argv[2], 0, 0);
    }

  mpf_set_default_prec (bprec);

  mpf_init_set_ui (limit_rerr, 1);
  mpf_div_2exp (limit_rerr, limit_rerr, bprec);
#if VERBOSE
  mpf_dump (limit_rerr);
#endif
  mpf_init (rerr);
  mpf_init_set_ui (max_rerr, 0);

  mpf_init (u);
  mpf_init (v);
  mpf_init (w);
  mpf_init (wref);
  for (i = 0; i < reps; i++)
    {
      size = urandom () % (2 * SIZE) - SIZE;
      exp = urandom () % SIZE;
      mpf_random2 (u, size, exp);

      size = urandom () % (2 * SIZE) - SIZE;
      exp = urandom () % SIZE;
      mpf_random2 (v, size, exp);

      if ((urandom () & 1) != 0)
	mpf_add_ui (u, v, 1);
      else if ((urandom () & 1) != 0)
	mpf_sub_ui (u, v, 1);

      mpf_sub (w, u, v);
      refmpf_sub (wref, u, v);

      mpf_reldiff (rerr, w, wref);
      if (mpf_cmp (rerr, max_rerr) > 0)
	{
	  mpf_set (max_rerr, rerr);
#if VERBOSE
	  mpf_dump (max_rerr);
#endif
	  if (mpf_cmp (rerr, limit_rerr) > 0)
	    {
	      printf ("ERROR after %d tests\n", i);
	      printf ("   u = "); mpf_dump (u);
	      printf ("   v = "); mpf_dump (v);
	      printf ("wref = "); mpf_dump (wref);
	      printf ("   w = "); mpf_dump (w);
	      abort ();
	    }
	}
    }

  mpf_clear (limit_rerr);
  mpf_clear (rerr);
  mpf_clear (max_rerr);

  mpf_clear (u);
  mpf_clear (v);
  mpf_clear (w);
  mpf_clear (wref);
}


void
check_data (void)
{
  static const struct {
    struct {
      int        exp, size;
      mp_limb_t  d[10];
    } x, y, want;

  } data[] = {
    { { 123, 2, { 8, 9 } },             { 123, 1, { 9 } }, { 122, 1, { 8 } } },

    /* f - f == 0, various sizes.
       These exercise a past problem (gmp 4.1.3 and earlier) where the
       result exponent was not zeroed on a zero result like this.  */
    { { 0, 0 }, { 0, 0 }, { 0, 0 } },
    { { 99, 1, { 1 } },             { 99, 1, { 1 } },             { 0, 0 } },
    { { 99, 2, { 123, 456 } },      { 99, 2, { 123, 456 } },      { 0, 0 } },
    { { 99, 3, { 123, 456, 789 } }, { 99, 3, { 123, 456, 789 } }, { 0, 0 } },

    /* High limbs cancel, leaving just the low limbs of the longer operand.
       This exercises a past problem (gmp 4.1.3 and earlier) where high zero
       limbs on the remainder were not stripped before truncating to the
       destination, causing loss of precision.  */
    { { 123, 2, { 8, 9 } },             { 123, 1, { 9 } }, { 122, 1, { 8 } } },
    { { 123, 3, { 8, 0, 9 } },          { 123, 1, { 9 } }, { 121, 1, { 8 } } },
    { { 123, 4, { 8, 0, 0, 9 } },       { 123, 1, { 9 } }, { 120, 1, { 8 } } },
    { { 123, 5, { 8, 0, 0, 0, 9 } },    { 123, 1, { 9 } }, { 119, 1, { 8 } } },
    { { 123, 6, { 8, 0, 0, 0, 0, 9 } }, { 123, 1, { 9 } }, { 118, 1, { 8 } } },

  };

  mpf_t  x, y, got, want;
  int  i, swap;

  mp_trace_base = 16;
  mpf_init (got);

  for (i = 0; i < numberof (data); i++)
    {
      for (swap = 0; swap <= 1; swap++)
        {
          PTR(x) = (mp_ptr) data[i].x.d;
          SIZ(x) = data[i].x.size;
          EXP(x) = data[i].x.exp;
          PREC(x) = numberof (data[i].x.d);
          MPF_CHECK_FORMAT (x);

          PTR(y) = (mp_ptr) data[i].y.d;
          SIZ(y) = data[i].y.size;
          EXP(y) = data[i].y.exp;
          PREC(y) = numberof (data[i].y.d);
          MPF_CHECK_FORMAT (y);

          PTR(want) = (mp_ptr) data[i].want.d;
          SIZ(want) = data[i].want.size;
          EXP(want) = data[i].want.exp;
          PREC(want) = numberof (data[i].want.d);
          MPF_CHECK_FORMAT (want);

          if (swap)
            {
              mpf_swap (x, y);
              SIZ(want) = - SIZ(want);
            }

          mpf_sub (got, x, y);
/*           MPF_CHECK_FORMAT (got); */

          if (mpf_cmp (got, want) != 0)
            {
              printf ("check_data() wrong reault at data[%d] (operands%s swapped)\n", i, swap ? "" : " not");
              mpf_trace ("x   ", x);
              mpf_trace ("y   ", y);
              mpf_trace ("got ", got);
              mpf_trace ("want", want);
              abort ();
            }
        }
    }

  mpf_clear (got);
}


int
main (int argc, char **argv)
{
  tests_start ();

  check_data ();
  check_rand (argc, argv);

  tests_end ();
  exit (0);
}
