66 lines
1.3 KiB
C
66 lines
1.3 KiB
C
#include "tommath_private.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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/* SPDX-License-Identifier: Unlicense */
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/* returns size of ASCII representation */
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mp_err mp_radix_size(const mp_int *a, int radix, int *size)
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{
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mp_err err;
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int 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_IS_ZERO(a)) {
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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 ((err = mp_init_copy(&t, a)) != MP_OKAY) {
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return err;
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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_IS_ZERO(&t)) {
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if ((err = mp_div_d(&t, (mp_digit)radix, &t, &d)) != MP_OKAY) {
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goto LBL_ERR;
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}
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++digs;
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}
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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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err = MP_OKAY;
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LBL_ERR:
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mp_clear(&t);
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return err;
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}
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#endif
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