diff libtommath/bn_mp_prime_is_divisible.c @ 330:5488db2e9e4e

merge of 332f709a4cb39cde4cedab7c3be89e05f3023067 and ca4ca78b82c5d430c69ce01bf794e8886ce81431
author Matt Johnston <matt@ucc.asn.au>
date Sat, 10 Jun 2006 16:39:40 +0000
parents eed26cff980b
children 5ff8218bcee9
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--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/libtommath/bn_mp_prime_is_divisible.c	Sat Jun 10 16:39:40 2006 +0000
@@ -0,0 +1,46 @@
+#include <tommath.h>
+#ifdef BN_MP_PRIME_IS_DIVISIBLE_C
+/* LibTomMath, multiple-precision integer library -- Tom St Denis
+ *
+ * LibTomMath is a library that provides multiple-precision
+ * integer arithmetic as well as number theoretic functionality.
+ *
+ * The library was designed directly after the MPI library by
+ * Michael Fromberger but has been written from scratch with
+ * additional optimizations in place.
+ *
+ * The library is free for all purposes without any express
+ * guarantee it works.
+ *
+ * Tom St Denis, [email protected], http://math.libtomcrypt.org
+ */
+
+/* determines if an integers is divisible by one 
+ * of the first PRIME_SIZE primes or not
+ *
+ * sets result to 0 if not, 1 if yes
+ */
+int mp_prime_is_divisible (mp_int * a, int *result)
+{
+  int     err, ix;
+  mp_digit res;
+
+  /* default to not */
+  *result = MP_NO;
+
+  for (ix = 0; ix < PRIME_SIZE; ix++) {
+    /* what is a mod LBL_prime_tab[ix] */
+    if ((err = mp_mod_d (a, ltm_prime_tab[ix], &res)) != MP_OKAY) {
+      return err;
+    }
+
+    /* is the residue zero? */
+    if (res == 0) {
+      *result = MP_YES;
+      return MP_OKAY;
+    }
+  }
+
+  return MP_OKAY;
+}
+#endif