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#include "tommath_private.h"
#ifdef BN_MP_TO_RADIX_C
/* LibTomMath, multiple-precision integer library -- Tom St Denis */
/* SPDX-License-Identifier: Unlicense */
/* stores a bignum as a ASCII string in a given radix (2..64)
*
* Stores upto "size - 1" chars and always a NULL byte, puts the number of characters
* written, including the '\0', in "written".
*/
mp_err mp_to_radix(const mp_int *a, char *str, size_t maxlen, size_t *written, int radix)
{
size_t digs;
mp_err err;
mp_int t;
mp_digit d;
char *_s = str;
/* check range of radix and size*/
if (maxlen < 2u) {
return MP_BUF;
}
if ((radix < 2) || (radix > 64)) {
return MP_VAL;
}
/* quick out if its zero */
if (MP_IS_ZERO(a)) {
*str++ = '0';
*str = '\0';
if (written != NULL) {
*written = 2u;
}
return MP_OKAY;
}
if ((err = mp_init_copy(&t, a)) != MP_OKAY) {
return err;
}
/* 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 = 0u;
while (!MP_IS_ZERO(&t)) {
if (--maxlen < 1u) {
/* no more room */
err = MP_BUF;
goto LBL_ERR;
}
if ((err = mp_div_d(&t, (mp_digit)radix, &t, &d)) != MP_OKAY) {
goto LBL_ERR;
}
*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
*/
s_mp_reverse((unsigned char *)_s, digs);
/* append a NULL so the string is properly terminated */
*str = '\0';
digs++;
if (written != NULL) {
*written = (a->sign == MP_NEG) ? (digs + 1u): digs;
}
LBL_ERR:
mp_clear(&t);
return err;
}
#endif
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