libtommath/mp_from_ubin.c

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#include "tommath_private.h"
#ifdef MP_FROM_UBIN_C
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/* LibTomMath, multiple-precision integer library -- Tom St Denis */
/* SPDX-License-Identifier: Unlicense */
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/* reads a unsigned char array, assumes the msb is stored first [big endian] */
mp_err mp_from_ubin(mp_int *a, const unsigned char *buf, size_t size)
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{
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mp_err err;
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/* make sure there are at least two digits */
if (a->alloc < 2) {
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if ((err = mp_grow(a, 2)) != MP_OKAY) {
return err;
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}
}
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/* zero the int */
mp_zero(a);
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/* read the bytes in */
while (size-- > 0u) {
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if ((err = mp_mul_2d(a, 8, a)) != MP_OKAY) {
return err;
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}
a->dp[0] |= *buf++;
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a->used += 1;
}
mp_clamp(a);
return MP_OKAY;
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}
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#endif