diff bn_mp_mod.c @ 1:22d5cf7d4b1a libtommath

Renaming branch
author Matt Johnston <matt@ucc.asn.au>
date Mon, 31 May 2004 18:23:46 +0000
parents
children d29b64170cf0
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--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/bn_mp_mod.c	Mon May 31 18:23:46 2004 +0000
@@ -0,0 +1,42 @@
+/* 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>
+
+/* c = a mod b, 0 <= c < b */
+int
+mp_mod (mp_int * a, mp_int * b, mp_int * c)
+{
+  mp_int  t;
+  int     res;
+
+  if ((res = mp_init (&t)) != MP_OKAY) {
+    return res;
+  }
+
+  if ((res = mp_div (a, b, NULL, &t)) != MP_OKAY) {
+    mp_clear (&t);
+    return res;
+  }
+
+  if (t.sign != b->sign) {
+    res = mp_add (b, &t, c);
+  } else {
+    res = MP_OKAY;
+    mp_exch (&t, c);
+  }
+
+  mp_clear (&t);
+  return res;
+}