ltm-0.41

lib/hcrypto/libtommath/bn_mp_reduce_2k_setup.c

@@ -0,0 +1,47 @@
+#include <tommath.h>
+#ifdef BN_MP_REDUCE_2K_SETUP_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, tomstdenis@gmail.com, http://libtom.org
+ */
+
+/* determines the setup value */
+int mp_reduce_2k_setup(mp_int *a, mp_digit *d)
+{
+   int res, p;
+   mp_int tmp;
+   
+   if ((res = mp_init(&tmp)) != MP_OKAY) {
+      return res;
+   }
+   
+   p = mp_count_bits(a);
+   if ((res = mp_2expt(&tmp, p)) != MP_OKAY) {
+      mp_clear(&tmp);
+      return res;
+   }
+   
+   if ((res = s_mp_sub(&tmp, a, &tmp)) != MP_OKAY) {
+      mp_clear(&tmp);
+      return res;
+   }
+   
+   *d = tmp.dp[0];
+   mp_clear(&tmp);
+   return MP_OKAY;
+}
+#endif
+
+/* $Source: /cvs/libtom/libtommath/bn_mp_reduce_2k_setup.c,v $ */
+/* $Revision: 1.4 $ */
+/* $Date: 2006/12/28 01:25:13 $ */