78 lines
1.9 KiB
C
78 lines
1.9 KiB
C
#include "tommath_private.h"
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#ifdef BN_MP_READ_RADIX_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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#define MP_TOUPPER(c) ((((c) >= 'a') && ((c) <= 'z')) ? (((c) + 'A') - 'a') : (c))
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/* read a string [ASCII] in a given radix */
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int mp_read_radix(mp_int *a, const char *str, int radix)
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{
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int y, res, neg;
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unsigned pos;
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char ch;
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/* zero the digit bignum */
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mp_zero(a);
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/* make sure the radix is ok */
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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 the leading digit is a
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* minus set the sign to negative.
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*/
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if (*str == '-') {
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++str;
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neg = MP_NEG;
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} else {
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neg = MP_ZPOS;
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}
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/* set the integer to the default of zero */
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mp_zero(a);
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/* process each digit of the string */
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while (*str != '\0') {
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/* if the radix <= 36 the conversion is case insensitive
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* this allows numbers like 1AB and 1ab to represent the same value
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* [e.g. in hex]
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*/
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ch = (radix <= 36) ? (char)MP_TOUPPER((int)*str) : *str;
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pos = (unsigned)(ch - '(');
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if (mp_s_rmap_reverse_sz < pos) {
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break;
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}
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y = (int)mp_s_rmap_reverse[pos];
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/* if the char was found in the map
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* and is less than the given radix add it
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* to the number, otherwise exit the loop.
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*/
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if ((y == 0xff) || (y >= radix)) {
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break;
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}
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if ((res = mp_mul_d(a, (mp_digit)radix, a)) != MP_OKAY) {
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return res;
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}
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if ((res = mp_add_d(a, (mp_digit)y, a)) != MP_OKAY) {
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return res;
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}
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++str;
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}
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/* if an illegal character was found, fail. */
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if (!((*str == '\0') || (*str == '\r') || (*str == '\n'))) {
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mp_zero(a);
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return MP_VAL;
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}
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/* set the sign only if a != 0 */
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if (!MP_IS_ZERO(a)) {
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a->sign = neg;
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}
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return MP_OKAY;
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}
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#endif
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