6907f6ca45
zero values returned a length of 1, not 2 in case of radix 2 re-ordering the special casing takes care of it
79 lines
1.7 KiB
C
79 lines
1.7 KiB
C
#include <tommath.h>
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#ifdef BN_MP_RADIX_SIZE_C
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/* LibTomMath, multiple-precision integer library -- Tom St Denis
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*
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* LibTomMath is a library that provides multiple-precision
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* integer arithmetic as well as number theoretic functionality.
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*
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* The library was designed directly after the MPI library by
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* Michael Fromberger but has been written from scratch with
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* additional optimizations in place.
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*
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* The library is free for all purposes without any express
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* guarantee it works.
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*
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* Tom St Denis, tomstdenis@gmail.com, http://libtom.org
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*/
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/* returns size of ASCII reprensentation */
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int mp_radix_size (mp_int * a, int radix, int *size)
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{
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int res, digs;
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mp_int t;
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mp_digit d;
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*size = 0;
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/* make sure the radix is in range */
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if (radix < 2 || radix > 64) {
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return MP_VAL;
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}
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if (mp_iszero(a) == MP_YES) {
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*size = 2;
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return MP_OKAY;
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}
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/* special case for binary */
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if (radix == 2) {
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*size = mp_count_bits (a) + (a->sign == MP_NEG ? 1 : 0) + 1;
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return MP_OKAY;
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}
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/* digs is the digit count */
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digs = 0;
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/* if it's negative add one for the sign */
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if (a->sign == MP_NEG) {
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++digs;
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}
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/* init a copy of the input */
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if ((res = mp_init_copy (&t, a)) != MP_OKAY) {
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return res;
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}
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/* force temp to positive */
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t.sign = MP_ZPOS;
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/* fetch out all of the digits */
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while (mp_iszero (&t) == MP_NO) {
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if ((res = mp_div_d (&t, (mp_digit) radix, &t, &d)) != MP_OKAY) {
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mp_clear (&t);
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return res;
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}
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++digs;
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}
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mp_clear (&t);
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/* return digs + 1, the 1 is for the NULL byte that would be required. */
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*size = digs + 1;
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return MP_OKAY;
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}
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#endif
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/* $Source$ */
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/* $Revision$ */
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/* $Date$ */
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