tommath/bn_mp_radix_size.c

79 lines
1.7 KiB
C
Raw Normal View History

#include <tommath_private.h>
2004-10-29 18:07:18 -04:00
#ifdef BN_MP_RADIX_SIZE_C
2003-08-04 21:24:44 -04:00
/* 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, tstdenis82@gmail.com, http://libtom.org
2003-08-04 21:24:44 -04:00
*/
/* returns size of ASCII reprensentation */
2004-01-25 12:40:21 -05:00
int mp_radix_size (mp_int * a, int radix, int *size)
2003-08-04 21:24:44 -04:00
{
int res, digs;
mp_int t;
mp_digit d;
2004-01-25 12:40:21 -05:00
*size = 0;
2003-12-24 13:59:22 -05:00
/* make sure the radix is in range */
if ((radix < 2) || (radix > 64)) {
2004-01-25 12:40:21 -05:00
return MP_VAL;
2003-08-04 21:24:44 -04:00
}
2005-03-12 06:55:11 -05:00
if (mp_iszero(a) == MP_YES) {
2005-11-18 00:16:19 -05:00
*size = 2;
2005-03-12 06:55:11 -05:00
return MP_OKAY;
2003-08-04 21:24:44 -04:00
}
/* special case for binary */
if (radix == 2) {
*size = mp_count_bits (a) + ((a->sign == MP_NEG) ? 1 : 0) + 1;
return MP_OKAY;
}
2003-12-24 13:59:22 -05:00
/* digs is the digit count */
2003-08-04 21:24:44 -04:00
digs = 0;
2003-12-24 13:59:22 -05:00
/* if it's negative add one for the sign */
2005-03-12 06:55:11 -05:00
if (a->sign == MP_NEG) {
2003-08-04 21:24:44 -04:00
++digs;
}
2005-03-12 06:55:11 -05:00
/* init a copy of the input */
if ((res = mp_init_copy (&t, a)) != MP_OKAY) {
return res;
}
/* force temp to positive */
t.sign = MP_ZPOS;
2003-12-24 13:59:22 -05:00
/* fetch out all of the digits */
2005-03-12 06:55:11 -05:00
while (mp_iszero (&t) == MP_NO) {
2003-08-04 21:24:44 -04:00
if ((res = mp_div_d (&t, (mp_digit) radix, &t, &d)) != MP_OKAY) {
mp_clear (&t);
2003-12-24 13:59:22 -05:00
return res;
2003-08-04 21:24:44 -04:00
}
++digs;
}
mp_clear (&t);
2003-12-24 13:59:22 -05:00
/* return digs + 1, the 1 is for the NULL byte that would be required. */
2004-01-25 12:40:21 -05:00
*size = digs + 1;
return MP_OKAY;
2003-08-04 21:24:44 -04:00
}
2004-10-29 18:07:18 -04:00
#endif
2005-08-01 12:37:28 -04:00
/* $Source$ */
/* $Revision$ */
/* $Date$ */