56 lines
1.1 KiB
C
56 lines
1.1 KiB
C
#include "tommath_private.h"
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#ifdef BN_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 LTM_NO_FILE
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/* read a bigint from a file stream in ASCII */
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int mp_fread(mp_int *a, int radix, FILE *stream)
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{
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int err, ch, neg, y;
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unsigned pos;
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/* clear a */
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mp_zero(a);
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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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} else {
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neg = MP_ZPOS;
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}
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for (;;) {
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pos = (unsigned)(ch - (int)'(');
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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 ((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, (mp_digit)y, a)) != MP_OKAY) {
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return err;
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}
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ch = fgetc(stream);
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}
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if (mp_cmp_d(a, 0uL) != MP_EQ) {
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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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