138 lines
2.7 KiB
C
138 lines
2.7 KiB
C
/* LibTomMath, multiple-precision integer library -- Tom St Denis
|
|
*
|
|
* LibTomMath is library that provides for multiple-precision
|
|
* integer arithmetic as well as number theoretic functionality.
|
|
*
|
|
* The library is 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>
|
|
|
|
/* chars used in radix conversions */
|
|
static const char *s_rmap = "0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz+/";
|
|
|
|
/* read a string [ASCII] in a given radix */
|
|
int
|
|
mp_read_radix (mp_int * a, char *str, int radix)
|
|
{
|
|
int y, res, neg;
|
|
char ch;
|
|
|
|
if (radix < 2 || radix > 64) {
|
|
return MP_VAL;
|
|
}
|
|
|
|
if (*str == '-') {
|
|
++str;
|
|
neg = MP_NEG;
|
|
} else {
|
|
neg = MP_ZPOS;
|
|
}
|
|
|
|
mp_zero (a);
|
|
while (*str) {
|
|
ch = (char) ((radix < 36) ? toupper (*str) : *str);
|
|
for (y = 0; y < 64; y++) {
|
|
if (ch == s_rmap[y]) {
|
|
break;
|
|
}
|
|
}
|
|
|
|
if (y < radix) {
|
|
if ((res = mp_mul_d (a, (mp_digit) radix, a)) != MP_OKAY) {
|
|
return res;
|
|
}
|
|
if ((res = mp_add_d (a, (mp_digit) y, a)) != MP_OKAY) {
|
|
return res;
|
|
}
|
|
} else {
|
|
break;
|
|
}
|
|
++str;
|
|
}
|
|
a->sign = neg;
|
|
return MP_OKAY;
|
|
}
|
|
|
|
/* 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;
|
|
|
|
if (radix < 2 || radix > 64) {
|
|
return MP_VAL;
|
|
}
|
|
|
|
if ((res = mp_init_copy (&t, a)) != MP_OKAY) {
|
|
return res;
|
|
}
|
|
|
|
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++ = s_rmap[d];
|
|
++digs;
|
|
}
|
|
bn_reverse ((unsigned char *)_s, digs);
|
|
*str++ = '\0';
|
|
mp_clear (&t);
|
|
return MP_OKAY;
|
|
}
|
|
|
|
/* returns size of ASCII reprensentation */
|
|
int
|
|
mp_radix_size (mp_int * a, int radix)
|
|
{
|
|
int res, digs;
|
|
mp_int t;
|
|
mp_digit d;
|
|
|
|
/* special case for binary */
|
|
if (radix == 2) {
|
|
return mp_count_bits (a) + (a->sign == MP_NEG ? 1 : 0) + 1;
|
|
}
|
|
|
|
if (radix < 2 || radix > 64) {
|
|
return 0;
|
|
}
|
|
|
|
if ((res = mp_init_copy (&t, a)) != MP_OKAY) {
|
|
return 0;
|
|
}
|
|
|
|
digs = 0;
|
|
if (t.sign == MP_NEG) {
|
|
++digs;
|
|
t.sign = MP_ZPOS;
|
|
}
|
|
|
|
while (mp_iszero (&t) == 0) {
|
|
if ((res = mp_div_d (&t, (mp_digit) radix, &t, &d)) != MP_OKAY) {
|
|
mp_clear (&t);
|
|
return 0;
|
|
}
|
|
++digs;
|
|
}
|
|
mp_clear (&t);
|
|
return digs + 1;
|
|
}
|