diff bn_mp_reduce_setup.c @ 2:86e0b50a9b58 libtommath-orig ltm-0.30-orig

ltm 0.30 orig import
author Matt Johnston <matt@ucc.asn.au>
date Mon, 31 May 2004 18:25:22 +0000
parents
children d29b64170cf0
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--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/bn_mp_reduce_setup.c	Mon May 31 18:25:22 2004 +0000
@@ -0,0 +1,29 @@
+/* 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
+ */
+#include <tommath.h>
+
+/* pre-calculate the value required for Barrett reduction
+ * For a given modulus "b" it calulates the value required in "a"
+ */
+int
+mp_reduce_setup (mp_int * a, mp_int * b)
+{
+  int     res;
+  
+  if ((res = mp_2expt (a, b->used * 2 * DIGIT_BIT)) != MP_OKAY) {
+    return res;
+  }
+  return mp_div (a, b, a, NULL);
+}