+/* Test mpz_powm, mpz_mul, mpz_mod, mpz_mod_ui, mpz_div_ui.
+
+Copyright 1991, 1993, 1994, 1996, 1999, 2000, 2001, 2009 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 debug_mp __GMP_PROTO ((mpz_t, int));
+
+int
+main (int argc, char **argv)
+{
+ mpz_t base, exp, mod;
+ mpz_t r1, r2, t1, exp2, base2;
+ mp_size_t base_size, exp_size, mod_size;
+ int i;
+ int reps = 1000;
+ gmp_randstate_ptr rands;
+ mpz_t bs;
+ unsigned long bsi, size_range;
+
+ tests_start ();
+ rands = RANDS;
+
+ mpz_init (bs);
+
+ if (argc == 2)
+ reps = atoi (argv[1]);
+
+ mpz_init (base);
+ mpz_init (exp);
+ mpz_init (mod);
+ mpz_init (r1);
+ mpz_init (r2);
+ mpz_init (t1);
+ mpz_init (exp2);
+ mpz_init (base2);
+
+ for (i = 0; i < reps; i++)
+ {
+ mpz_urandomb (bs, rands, 32);
+ size_range = mpz_get_ui (bs) % 13 + 2;
+
+ do /* Loop until mathematically well-defined. */
+ {
+ mpz_urandomb (bs, rands, size_range);
+ base_size = mpz_get_ui (bs);
+ mpz_rrandomb (base, rands, base_size);
+
+ mpz_urandomb (bs, rands, 7L);
+ exp_size = mpz_get_ui (bs);
+ mpz_rrandomb (exp, rands, exp_size);
+ }
+ while (mpz_cmp_ui (base, 0) == 0 && mpz_cmp_ui (exp, 0) == 0);
+
+ do
+ {
+ mpz_urandomb (bs, rands, size_range);
+ mod_size = mpz_get_ui (bs);
+ mpz_rrandomb (mod, rands, mod_size);
+ }
+ while (mpz_cmp_ui (mod, 0) == 0);
+
+ mpz_urandomb (bs, rands, 2);
+ bsi = mpz_get_ui (bs);
+ if ((bsi & 1) != 0)
+ mpz_neg (base, base);
+
+ /* printf ("%ld %ld %ld\n", SIZ (base), SIZ (exp), SIZ (mod)); */
+
+ mpz_powm (r1, base, exp, mod);
+ MPZ_CHECK_FORMAT (r1);
+
+ mpz_set_ui (r2, 1);
+ mpz_mod (base2, base, mod);
+ mpz_set (exp2, exp);
+ mpz_mod (r2, r2, mod);
+
+ for (;;)
+ {
+ if (mpz_tstbit (exp2, 0))
+ {
+ mpz_mul (r2, r2, base2);
+ mpz_mod (r2, r2, mod);
+ }
+ if (mpz_cmp_ui (exp2, 1) <= 0)
+ break;
+ mpz_mul (base2, base2, base2);
+ mpz_mod (base2, base2, mod);
+ mpz_tdiv_q_2exp (exp2, exp2, 1);
+ }
+
+ if (mpz_cmp (r1, r2) != 0)
+ {
+ fprintf (stderr, "\nIncorrect results in test %d for operands:\n", i);
+ debug_mp (base, -16);
+ debug_mp (exp, -16);
+ debug_mp (mod, -16);
+ fprintf (stderr, "mpz_powm result:\n");
+ debug_mp (r1, -16);
+ fprintf (stderr, "reference result:\n");
+ debug_mp (r2, -16);
+ abort ();
+ }
+ }
+
+ mpz_clear (bs);
+ mpz_clear (base);
+ mpz_clear (exp);
+ mpz_clear (mod);
+ mpz_clear (r1);
+ mpz_clear (r2);
+ mpz_clear (t1);
+ mpz_clear (exp2);
+ mpz_clear (base2);
+
+ tests_end ();
+ exit (0);
+}
+
+void
+debug_mp (mpz_t x, int base)
+{
+ mpz_out_str (stderr, base, x); fputc ('\n', stderr);
+}