70 lines
1.7 KiB
C
70 lines
1.7 KiB
C
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#include "tommath_private.h"
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#ifdef 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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/* read a string [ASCII] in a given radix */
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mp_err mp_read_radix(mp_int *a, const char *str, int radix)
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{
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mp_err err;
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mp_sign sign = MP_ZPOS;
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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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sign = MP_NEG;
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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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uint8_t y;
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char ch = (radix <= 36) ? (char)MP_TOUPPER((int)*str) : *str;
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unsigned pos = (unsigned)(ch - '+');
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if (MP_RADIX_MAP_REVERSE_SIZE <= pos) {
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break;
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}
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y = s_mp_radix_map_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 >= radix) {
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break;
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}
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if ((err = mp_mul_d(a, (mp_digit)radix, a)) != MP_OKAY) {
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return err;
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}
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if ((err = mp_add_d(a, y, a)) != MP_OKAY) {
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return err;
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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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return MP_VAL;
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}
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/* set the sign only if a != 0 */
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if (!mp_iszero(a)) {
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a->sign = sign;
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}
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return MP_OKAY;
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}
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#endif
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