96 lines
2.1 KiB
C
96 lines
2.1 KiB
C
|
#include "tommath_private.h"
|
||
|
|
#ifdef MP_TO_RADIX_C
|
||
|
|
/* LibTomMath, multiple-precision integer library -- Tom St Denis */
|
||
|
|
/* SPDX-License-Identifier: Unlicense */
|
||
|
|
|
||
|
|
/* reverse an array, used for radix code */
|
||
|
|
static void s_reverse(char *s, size_t len)
|
||
|
|
{
|
||
|
|
size_t ix = 0, iy = len - 1u;
|
||
|
|
while (ix < iy) {
|
||
|
|
MP_EXCH(char, s[ix], s[iy]);
|
||
|
|
++ix;
|
||
|
|
--iy;
|
||
|
|
}
|
||
|
|
}
|
||
|
|
|
||
|
|
/* 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_iszero(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 (mp_isneg(&t)) {
|
||
|
|
/* 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_iszero(&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++ = s_mp_radix_map[d];
|
||
|
|
++digs;
|
||
|
|
}
|
||
|
|
/* reverse the digits of the string. In this case _s points
|
||
|
|
* to the first digit [excluding the sign] of the number
|
||
|
|
*/
|
||
|
|
s_reverse(_s, digs);
|
||
|
|
|
||
|
|
/* append a NULL so the string is properly terminated */
|
||
|
|
*str = '\0';
|
||
|
|
digs++;
|
||
|
|
|
||
|
|
if (written != NULL) {
|
||
|
|
*written = mp_isneg(a) ? (digs + 1u): digs;
|
||
|
|
}
|
||
|
|
|
||
|
|
LBL_ERR:
|
||
|
|
mp_clear(&t);
|
||
|
|
return err;
|
||
|
|
}
|
||
|
|
|
||
|
|
#endif
|