/* 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;
}
/* 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 (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;
}
/* read a bigint from a file stream in ASCII */
int mp_fread(mp_int *a, int radix, FILE *stream)
{
int err, ch, neg, y;
/* clear a */
mp_zero(a);
/* if first digit is - then set negative */
ch = fgetc(stream);
if (ch == '-') {
neg = MP_NEG;
ch = fgetc(stream);
} else {
neg = MP_ZPOS;
}
for (;;) {
/* find y in the radix map */
for (y = 0; y < radix; y++) {
if (s_rmap[y] == ch) {
break;
}
}
if (y == radix) {
break;
}
/* shift up and add */
if ((err = mp_mul_d(a, radix, a)) != MP_OKAY) {
return err;
}
if ((err = mp_add_d(a, y, a)) != MP_OKAY) {
return err;
}
ch = fgetc(stream);
}
if (mp_cmp_d(a, 0) != MP_EQ) {
a->sign = neg;
}
return MP_OKAY;
}
int mp_fwrite(mp_int *a, int radix, FILE *stream)
{
char *buf;
int err, len, x;
len = mp_radix_size(a, radix);
if (len == 0) {
return MP_VAL;
}
buf = malloc(len);
if (buf == NULL) {
return MP_MEM;
}
if ((err = mp_toradix(a, buf, radix)) != MP_OKAY) {
free(buf);
return err;
}
for (x = 0; x < len; x++) {
if (fputc(buf[x], stream) == EOF) {
free(buf);
return MP_VAL;
}
}
free(buf);
return MP_OKAY;
}
