github.com/aergoio/aergo@v1.3.1/libtool/src/gmp-6.1.2/tests/mpz/t-div_2exp.c

/* Test mpz_[cft]div_[qr]_2exp.

Copyright 2001 Free Software Foundation, Inc.

This file is part of the GNU MP Library test suite.

The GNU MP Library test suite 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; either version 3 of the License,
or (at your option) any later version.

The GNU MP Library test suite 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
the GNU MP Library test suite.  If not, see https://www.gnu.org/licenses/.  */

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

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


/* If the remainder is in the correct range and q*d+r is correct, then q
   must have rounded correctly.  */

void
check_one (mpz_srcptr a, unsigned long d)
{
  mpz_t  q, r, p, d2exp;
  int    inplace;

  mpz_init (d2exp);
  mpz_init (q);
  mpz_init (r);
  mpz_init (p);

  mpz_set_ui (d2exp, 1L);
  mpz_mul_2exp (d2exp, d2exp, d);

#define INPLACE(fun,dst,src,d)  \
  if (inplace)                  \
    {                           \
      mpz_set (dst, src);       \
      fun (dst, dst, d);        \
    }                           \
  else                          \
    fun (dst, src, d);

  for (inplace = 0; inplace <= 1; inplace++)
    {
      INPLACE (mpz_fdiv_q_2exp, q, a, d);
      INPLACE (mpz_fdiv_r_2exp, r, a, d);

      mpz_mul_2exp (p, q, d);
      mpz_add (p, p, r);
      if (mpz_sgn (r) < 0 || mpz_cmp (r, d2exp) >= 0)
	{
	  printf ("mpz_fdiv_r_2exp result out of range\n");
	  goto error;
	}
      if (mpz_cmp (p, a) != 0)
	{
	  printf ("mpz_fdiv_[qr]_2exp doesn't multiply back\n");
	  goto error;
	}


      INPLACE (mpz_cdiv_q_2exp, q, a, d);
      INPLACE (mpz_cdiv_r_2exp, r, a, d);

      mpz_mul_2exp (p, q, d);
      mpz_add (p, p, r);
      if (mpz_sgn (r) > 0 || mpz_cmpabs (r, d2exp) >= 0)
	{
	  printf ("mpz_cdiv_r_2exp result out of range\n");
	  goto error;
	}
      if (mpz_cmp (p, a) != 0)
	{
	  printf ("mpz_cdiv_[qr]_2exp doesn't multiply back\n");
	  goto error;
	}


      INPLACE (mpz_tdiv_q_2exp, q, a, d);
      INPLACE (mpz_tdiv_r_2exp, r, a, d);

      mpz_mul_2exp (p, q, d);
      mpz_add (p, p, r);
      if (mpz_sgn (r) != 0 && mpz_sgn (r) != mpz_sgn (a))
	{
	  printf ("mpz_tdiv_r_2exp result wrong sign\n");
	  goto error;
	}
      if (mpz_cmpabs (r, d2exp) >= 0)
	{
	  printf ("mpz_tdiv_r_2exp result out of range\n");
	  goto error;
	}
      if (mpz_cmp (p, a) != 0)
	{
	  printf ("mpz_tdiv_[qr]_2exp doesn't multiply back\n");
	  goto error;
	}
    }

  mpz_clear (d2exp);
  mpz_clear (q);
  mpz_clear (r);
  mpz_clear (p);
  return;


 error:
  mpz_trace ("a", a);
  printf    ("d=%lu\n", d);
  mpz_trace ("q", q);
  mpz_trace ("r", r);
  mpz_trace ("p", p);

  mp_trace_base = -16;
  mpz_trace ("a", a);
  printf    ("d=0x%lX\n", d);
  mpz_trace ("q", q);
  mpz_trace ("r", r);
  mpz_trace ("p", p);

  abort ();
}


void
check_all (mpz_ptr a, unsigned long d)
{
  check_one (a, d);
  mpz_neg (a, a);
  check_one (a, d);
}


void
check_various (void)
{
  static const unsigned long  table[] = {
    0, 1, 2, 3, 4, 5,
    GMP_NUMB_BITS-1, GMP_NUMB_BITS, GMP_NUMB_BITS+1,
    2*GMP_NUMB_BITS-1, 2*GMP_NUMB_BITS, 2*GMP_NUMB_BITS+1,
    3*GMP_NUMB_BITS-1, 3*GMP_NUMB_BITS, 3*GMP_NUMB_BITS+1,
    4*GMP_NUMB_BITS-1, 4*GMP_NUMB_BITS, 4*GMP_NUMB_BITS+1
  };

  int            i, j;
  unsigned long  n, d;
  mpz_t          a;

  mpz_init (a);

  /* a==0, and various d */
  mpz_set_ui (a, 0L);
  for (i = 0; i < numberof (table); i++)
    check_one (a, table[i]);

  /* a==2^n, and various d */
  for (i = 0; i < numberof (table); i++)
    {
      n = table[i];
      mpz_set_ui (a, 1L);
      mpz_mul_2exp (a, a, n);

      for (j = 0; j < numberof (table); j++)
	{
	  d = table[j];
	  check_all (a, d);
	}
    }

  mpz_clear (a);
}


void
check_random (int argc, char *argv[])
{
  gmp_randstate_ptr  rands = RANDS;
  int            reps = 100;
  mpz_t          a;
  unsigned long  d;
  int            i;

  if (argc == 2)
    reps = atoi (argv[1]);

  mpz_init (a);

  for (i = 0; i < reps; i++)
    {
      /* exponentially within 2 to 257 bits */
      mpz_erandomb (a, rands, urandom () % 8 + 2);

      d = urandom () % 256;

      check_all (a, d);
    }

  mpz_clear (a);
}


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

  check_various ();
  check_random (argc, argv);

  tests_end ();
  exit (0);
}