--- /dev/null
+/* test mpz_congruent_2exp_p */
+
+/*
+Copyright 2001 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 3 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. If not, see http://www.gnu.org/licenses/. */
+
+#include <stdio.h>
+#include <stdlib.h>
+#include "gmp.h"
+#include "gmp-impl.h"
+#include "tests.h"
+
+
+void
+check_one (mpz_srcptr a, mpz_srcptr c, unsigned long d, int want)
+{
+ mpz_t diff, d2exp;
+ int got;
+ int swap;
+
+ for (swap = 0; swap <= 1; swap++)
+ {
+ got = (mpz_congruent_2exp_p (a, c, d) != 0);
+ if (want != got)
+ {
+ mpz_init (diff);
+ mpz_init (d2exp);
+
+ mpz_sub (diff, a, c);
+ mpz_set_ui (d2exp, 1L);
+ mpz_mul_2exp (d2exp, d2exp, d);
+
+ printf ("mpz_congruent_2exp_p wrong\n");
+ printf (" expected %d got %d\n", want, got);
+ mpz_trace (" a", a);
+ mpz_trace (" c", c);
+ mpz_trace (" a-c", diff);
+ mpz_trace (" 2^d", d2exp);
+ printf (" d=%lu\n", d);
+
+ mp_trace_base = -16;
+ mpz_trace (" a", a);
+ mpz_trace (" c", c);
+ mpz_trace (" a-c", diff);
+ mpz_trace (" 2^d", d2exp);
+ printf (" d=0x%lX\n", d);
+ abort ();
+ }
+
+ MPZ_SRCPTR_SWAP (a, c);
+ }
+}
+
+
+void
+check_data (void)
+{
+ static const struct {
+ const char *a;
+ const char *c;
+ unsigned long d;
+ int want;
+
+ } data[] = {
+
+ /* anything is congruent mod 1 */
+ { "0", "0", 0, 1 },
+ { "1", "0", 0, 1 },
+ { "0", "1", 0, 1 },
+ { "123", "456", 0, 1 },
+ { "0x123456789123456789", "0x987654321987654321", 0, 1 },
+
+ };
+
+ mpz_t a, c;
+ int i;
+
+ mpz_init (a);
+ mpz_init (c);
+
+ for (i = 0; i < numberof (data); i++)
+ {
+ mpz_set_str_or_abort (a, data[i].a, 0);
+ mpz_set_str_or_abort (c, data[i].c, 0);
+ check_one (a, c, data[i].d, data[i].want);
+ }
+
+ mpz_clear (a);
+ mpz_clear (c);
+}
+
+
+void
+check_random (int argc, char *argv[])
+{
+ gmp_randstate_ptr rands = RANDS;
+ unsigned long d;
+ mpz_t a, c, ra, rc;
+ int i;
+ int want;
+ int reps = 5000;
+
+ if (argc >= 2)
+ reps = atoi (argv[1]);
+
+ mpz_init (a);
+ mpz_init (c);
+ mpz_init (ra);
+ mpz_init (rc);
+
+ for (i = 0; i < reps; i++)
+ {
+ mpz_errandomb (a, rands, 8*BITS_PER_MP_LIMB);
+ mpz_errandomb (c, rands, 8*BITS_PER_MP_LIMB);
+ d = urandom() % (8*BITS_PER_MP_LIMB);
+
+ mpz_mul_2exp (a, a, urandom() % (2*BITS_PER_MP_LIMB));
+ mpz_mul_2exp (c, c, urandom() % (2*BITS_PER_MP_LIMB));
+
+ mpz_negrandom (a, rands);
+ mpz_negrandom (c, rands);
+
+ mpz_fdiv_r_2exp (ra, a, d);
+ mpz_fdiv_r_2exp (rc, c, d);
+
+ want = (mpz_cmp (ra, rc) == 0);
+ check_one (a, c, d, want);
+
+ mpz_sub (ra, ra, rc);
+ mpz_sub (a, a, ra);
+ check_one (a, c, d, 1);
+ }
+
+ mpz_clear (a);
+ mpz_clear (c);
+ mpz_clear (ra);
+ mpz_clear (rc);
+}
+
+
+int
+main (int argc, char *argv[])
+{
+ tests_start ();
+
+ check_data ();
+ check_random (argc, argv);
+
+ tests_end ();
+ exit (0);
+}