67 lines
1.3 KiB
C
67 lines
1.3 KiB
C
#include "tommath_private.h"
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#ifdef MP_FREAD_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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#ifndef MP_NO_FILE
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/* read a bigint from a file stream in ASCII */
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mp_err mp_fread(mp_int *a, int radix, FILE *stream)
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{
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mp_err err;
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mp_sign neg = MP_ZPOS;
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int ch;
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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 first digit is - then set negative */
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ch = fgetc(stream);
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if (ch == (int)'-') {
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neg = MP_NEG;
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ch = fgetc(stream);
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}
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/* no digits, return error */
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if (ch == EOF) {
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return MP_ERR;
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}
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/* clear a */
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mp_zero(a);
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do {
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uint8_t y;
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unsigned pos;
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ch = (radix <= 36) ? MP_TOUPPER(ch) : ch;
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pos = (unsigned)(ch - (int)'(');
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if (MP_RMAP_REVERSE_SIZE < pos) {
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break;
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}
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y = s_mp_rmap_reverse[pos];
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if ((y == 0xff) || (y >= radix)) {
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break;
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}
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/* shift up and add */
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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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} while ((ch = fgetc(stream)) != EOF);
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if (!mp_iszero(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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#endif
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