1 files changed, 71 insertions, 0 deletions
diff --git a/bn_mp_toradix.c b/bn_mp_toradix.c
new file mode 100644
index 0000000..a206d5e
--- /dev/null
+++ b/bn_mp_toradix.c
@@ -0,0 +1,71 @@
+#include <tommath.h>
+#ifdef BN_MP_TORADIX_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@iahu.ca, http://math.libtomcrypt.org
+ */
+
+/* stores a bignum as a ASCII string in a given radix (2..64) */
+int mp_toradix (mp_int * a, char *str, int radix)
+{
+  int     res, digs;
+  mp_int  t;
+  mp_digit d;
+  char   *_s = str;
+
+  /* check range of the radix */
+  if (radix < 2 || radix > 64) {
+    return MP_VAL;
+  }
+
+  /* quick out if its zero */
+  if (mp_iszero(a) == 1) {
+     *str++ = '0';
+     *str = '\0';
+     return MP_OKAY;
+  }
+
+  if ((res = mp_init_copy (&t, a)) != MP_OKAY) {
+    return res;
+  }
+
+  /* if it is negative output a - */
+  if (t.sign == MP_NEG) {
+    ++_s;
+    *str++ = '-';
+    t.sign = MP_ZPOS;
+  }
+
+  digs = 0;
+  while (mp_iszero (&t) == 0) {
+    if ((res = mp_div_d (&t, (mp_digit) radix, &t, &d)) != MP_OKAY) {
+      mp_clear (&t);
+      return res;
+    }
+    *str++ = mp_s_rmap[d];
+    ++digs;
+  }
+
+  /* reverse the digits of the string.  In this case _s points
+   * to the first digit [exluding the sign] of the number]
+   */
+  bn_reverse ((unsigned char *)_s, digs);
+
+  /* append a NULL so the string is properly terminated */
+  *str = '\0';
+
+  mp_clear (&t);
+  return MP_OKAY;
+}
+
+#endif