/* 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
*/
#include <tommath.h>
/* 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;
}
