iw7-mod/deps/libtommath/mp_fread.c

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2024-08-13 05:15:34 -04:00
#include "tommath_private.h"
#ifdef MP_FREAD_C
/* LibTomMath, multiple-precision integer library -- Tom St Denis */
/* SPDX-License-Identifier: Unlicense */
#ifndef MP_NO_FILE
/* read a bigint from a file stream in ASCII */
mp_err mp_fread(mp_int *a, int radix, FILE *stream)
{
mp_err err;
mp_sign sign = MP_ZPOS;
int ch;
/* make sure the radix is ok */
if ((radix < 2) || (radix > 64)) {
return MP_VAL;
}
/* if first digit is - then set negative */
ch = fgetc(stream);
if (ch == (int)'-') {
sign = MP_NEG;
ch = fgetc(stream);
}
/* no digits, return error */
if (ch == EOF) {
return MP_ERR;
}
/* clear a */
mp_zero(a);
do {
uint8_t y;
unsigned pos;
ch = (radix <= 36) ? MP_TOUPPER(ch) : ch;
pos = (unsigned)(ch - (int)'+');
if (MP_RADIX_MAP_REVERSE_SIZE <= pos) {
break;
}
y = s_mp_radix_map_reverse[pos];
if (y >= radix) {
break;
}
/* shift up and add */
if ((err = mp_mul_d(a, (mp_digit)radix, a)) != MP_OKAY) {
return err;
}
if ((err = mp_add_d(a, y, a)) != MP_OKAY) {
return err;
}
} while ((ch = fgetc(stream)) != EOF);
if (!mp_iszero(a)) {
a->sign = sign;
}
return MP_OKAY;
}
#endif
#endif