55 lines
1.2 KiB
C
55 lines
1.2 KiB
C
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/* LibTomMath, multiple-precision integer library -- Tom St Denis
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*
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* LibTomMath is library that provides for multiple-precision
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* integer arithmetic as well as number theoretic functionality.
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*
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* The library is 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@iahu.ca, http://math.libtomcrypt.org
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*/
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#include <tommath.h>
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/* returns size of ASCII reprensentation */
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int
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mp_radix_size (mp_int * a, int radix)
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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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/* special case for binary */
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if (radix == 2) {
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return mp_count_bits (a) + (a->sign == MP_NEG ? 1 : 0) + 1;
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}
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if (radix < 2 || radix > 64) {
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return 0;
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}
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if ((res = mp_init_copy (&t, a)) != MP_OKAY) {
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return 0;
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}
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digs = 0;
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if (t.sign == MP_NEG) {
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++digs;
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t.sign = MP_ZPOS;
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}
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while (mp_iszero (&t) == 0) {
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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 0;
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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;
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}
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