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authorKevin B Kenny <kennykb@acm.org>2005-01-19 22:41:26 (GMT)
committerKevin B Kenny <kennykb@acm.org>2005-01-19 22:41:26 (GMT)
commitef78ca64ce6ba6a8786f083318fe536f2bd52925 (patch)
tree47f8ad0d7291237c7f9af988c5e05275ed9286ee /libtommath/bn_mp_toradix_n.c
parentb23d942a1e86ddee18c2309afd7fa7e9afa79ef8 (diff)
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Import of libtommath 0.33
Diffstat (limited to 'libtommath/bn_mp_toradix_n.c')
-rw-r--r--libtommath/bn_mp_toradix_n.c85
1 files changed, 85 insertions, 0 deletions
diff --git a/libtommath/bn_mp_toradix_n.c b/libtommath/bn_mp_toradix_n.c
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+++ b/libtommath/bn_mp_toradix_n.c
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+#include <tommath.h>
+#ifdef BN_MP_TORADIX_N_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)
+ *
+ * Stores upto maxlen-1 chars and always a NULL byte
+ */
+int mp_toradix_n(mp_int * a, char *str, int radix, int maxlen)
+{
+ int res, digs;
+ mp_int t;
+ mp_digit d;
+ char *_s = str;
+
+ /* check range of the maxlen, radix */
+ if (maxlen < 3 || 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) {
+ /* we have to reverse our digits later... but not the - sign!! */
+ ++_s;
+
+ /* store the flag and mark the number as positive */
+ *str++ = '-';
+ t.sign = MP_ZPOS;
+
+ /* subtract a char */
+ --maxlen;
+ }
+
+ 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;
+
+ if (--maxlen == 1) {
+ /* no more room */
+ break;
+ }
+ }
+
+ /* 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