diff libtommath/bn_mp_reduce_is_2k_l.c @ 389:5ff8218bcee9

propagate from branch 'au.asn.ucc.matt.ltm.dropbear' (head 2af95f00ebd5bb7a28b3817db1218442c935388e) to branch 'au.asn.ucc.matt.dropbear' (head ecd779509ef23a8cdf64888904fc9b31d78aa933)
author Matt Johnston <matt@ucc.asn.au>
date Thu, 11 Jan 2007 03:14:55 +0000
parents eed26cff980b
children 60fc6476e044
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--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/libtommath/bn_mp_reduce_is_2k_l.c	Thu Jan 11 03:14:55 2007 +0000
@@ -0,0 +1,44 @@
+#include <tommath.h>
+#ifdef BN_MP_REDUCE_IS_2K_L_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.com
+ */
+
+/* determines if reduce_2k_l can be used */
+int mp_reduce_is_2k_l(mp_int *a)
+{
+   int ix, iy;
+   
+   if (a->used == 0) {
+      return MP_NO;
+   } else if (a->used == 1) {
+      return MP_YES;
+   } else if (a->used > 1) {
+      /* if more than half of the digits are -1 we're sold */
+      for (iy = ix = 0; ix < a->used; ix++) {
+          if (a->dp[ix] == MP_MASK) {
+              ++iy;
+          }
+      }
+      return (iy >= (a->used/2)) ? MP_YES : MP_NO;
+      
+   }
+   return MP_NO;
+}
+
+#endif
+
+/* $Source: /cvs/libtom/libtommath/bn_mp_reduce_is_2k_l.c,v $ */
+/* $Revision: 1.3 $ */
+/* $Date: 2006/03/31 14:18:44 $ */