[Gmp-commit] /var/hg/gmp: 2 new changesets

[mercurial at gmplib.org]

details:   /var/hg/gmp/rev/c0d407af48fb
changeset: 17989:c0d407af48fb
user:      Marco Bodrato <bodrato at mail.dm.unipi.it>
date:      Sun Dec 08 21:57:25 2019 +0100
description:
mpz/powm.c: Full normalisation when e=1 & b<0...

details:   /var/hg/gmp/rev/8fb9e39a9d04
changeset: 17990:8fb9e39a9d04
user:      Marco Bodrato <bodrato at mail.dm.unipi.it>
date:      Sun Dec 08 21:58:59 2019 +0100
description:
tests/mpz/t-powm.c: Trigger the just removed bug.

diffstat:

 mpz/powm.c         |   2 +-
 tests/mpz/t-powm.c |  23 +++++++++++++++++++++++
 2 files changed, 24 insertions(+), 1 deletions(-)

diffs (45 lines):

diff -r 2109bbf292bd -r 8fb9e39a9d04 mpz/powm.c
--- a/mpz/powm.c	Thu Dec 05 07:44:46 2019 +0100
+++ b/mpz/powm.c	Sun Dec 08 21:58:59 2019 +0100
@@ -138,7 +138,7 @@
 	    {
 	      mpn_sub (rp, mp, n, bp, bn);
 	      rn = n;
-	      rn -= (rp[rn - 1] == 0);
+	      MPN_NORMALIZE_NOT_ZERO (rp, rn);
 	    }
 	  else
 	    {
diff -r 2109bbf292bd -r 8fb9e39a9d04 tests/mpz/t-powm.c
--- a/tests/mpz/t-powm.c	Thu Dec 05 07:44:46 2019 +0100
+++ b/tests/mpz/t-powm.c	Sun Dec 08 21:58:59 2019 +0100
@@ -71,6 +71,29 @@
   mpz_init (exp2);
   mpz_init (base2);
 
+  mpz_set_ui (exp, 1);
+  mpz_set_ui (mod, 1);
+  mpz_setbit (mod, 10 * GMP_NUMB_BITS);
+  mpz_ui_sub (base, 3, mod);
+  mpz_powm (r1, base, exp, mod);
+  MPZ_CHECK_FORMAT (r1);
+  mpz_powm_sec (r2, base, exp, mod);
+  MPZ_CHECK_FORMAT (r2);
+
+  if (mpz_cmp_ui (r1, 3) != 0 || mpz_cmp_ui (r2, 3) != 0)
+    {
+      fprintf (stderr, "\nIncorrect results in first test 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, "mpz_powm_sec result:\n");
+      debug_mp (r2, -16);
+      fprintf (stderr, "reference result: 3\n");
+      abort ();
+    }
+
   memset (allsizes, 0, (1 << (SIZEM + 2 - 1)) * sizeof (int));
 
   for (i = 0; i < reps || ! allsizes_seen (allsizes); i++)