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authorChih-hung Hsieh <chh@google.com>2015-09-25 14:51:48 +0000
committerGerrit Code Review <noreply-gerritcodereview@google.com>2015-09-25 14:51:48 +0000
commitb0121c5547604527aaeea297b54047cd14b234df (patch)
tree7d9031ee3d5796de4a1825892fc6e04ba6e36ae2 /lib/next_prime.c
parentd03895cf5f8b77c6a85abcd84ea0d80ff56be846 (diff)
parent5eafdf0f9bfd9a3c5f93414ac16bb399b6da0b7f (diff)
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Merge "Move files up to match upstream source structure."
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diff --git a/lib/next_prime.c b/lib/next_prime.c
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+/* Determine prime number.
+ Copyright (C) 2006 Red Hat, Inc.
+ This file is part of elfutils.
+ Written by Ulrich Drepper <drepper@redhat.com>, 2000.
+
+ This file is free software; you can redistribute it and/or modify
+ it under the terms of either
+
+ * 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
+
+ or
+
+ * the GNU General Public License as published by the Free
+ Software Foundation; either version 2 of the License, or (at
+ your option) any later version
+
+ or both in parallel, as here.
+
+ elfutils 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 copies of the GNU General Public License and
+ the GNU Lesser General Public License along with this program. If
+ not, see <http://www.gnu.org/licenses/>. */
+
+#include <stddef.h>
+
+
+/* Test whether CANDIDATE is a prime. */
+static int
+is_prime (size_t candidate)
+{
+ /* No even number and none less than 10 will be passed here. */
+ size_t divn = 3;
+ size_t sq = divn * divn;
+
+ while (sq < candidate && candidate % divn != 0)
+ {
+ size_t old_sq = sq;
+ ++divn;
+ sq += 4 * divn;
+ if (sq < old_sq)
+ return 1;
+ ++divn;
+ }
+
+ return candidate % divn != 0;
+}
+
+
+/* We need primes for the table size. */
+size_t
+next_prime (size_t seed)
+{
+ /* Make it definitely odd. */
+ seed |= 1;
+
+ while (!is_prime (seed))
+ seed += 2;
+
+ return seed;
+}