annotate libtommath/bn_mp_unpack.c @ 1853:2be3115a8762 default tip main master

debugging test runner authorized_keys perms
author Matt Johnston <matt@ucc.asn.au>
date Tue, 19 Oct 2021 13:45:59 +0800
parents 1051e4eea25a
children
Ignore whitespace changes - Everywhere: Within whitespace: At end of lines:
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1 #include "tommath_private.h"
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2 #ifdef BN_MP_UNPACK_C
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3 /* LibTomMath, multiple-precision integer library -- Tom St Denis */
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4 /* SPDX-License-Identifier: Unlicense */
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5
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6 /* based on gmp's mpz_import.
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7 * see http://gmplib.org/manual/Integer-Import-and-Export.html
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8 */
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9 mp_err mp_unpack(mp_int *rop, size_t count, mp_order order, size_t size,
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10 mp_endian endian, size_t nails, const void *op)
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11 {
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12 mp_err err;
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13 size_t odd_nails, nail_bytes, i, j;
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14 unsigned char odd_nail_mask;
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15
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16 mp_zero(rop);
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17
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18 if (endian == MP_NATIVE_ENDIAN) {
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19 MP_GET_ENDIANNESS(endian);
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20 }
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21
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22 odd_nails = (nails % 8u);
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23 odd_nail_mask = 0xff;
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24 for (i = 0; i < odd_nails; ++i) {
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25 odd_nail_mask ^= (unsigned char)(1u << (7u - i));
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26 }
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27 nail_bytes = nails / 8u;
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28
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29 for (i = 0; i < count; ++i) {
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30 for (j = 0; j < (size - nail_bytes); ++j) {
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31 unsigned char byte = *((const unsigned char *)op +
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32 (((order == MP_MSB_FIRST) ? i : ((count - 1u) - i)) * size) +
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33 ((endian == MP_BIG_ENDIAN) ? (j + nail_bytes) : (((size - 1u) - j) - nail_bytes)));
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34
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35 if ((err = mp_mul_2d(rop, (j == 0u) ? (int)(8u - odd_nails) : 8, rop)) != MP_OKAY) {
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36 return err;
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37 }
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38
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39 rop->dp[0] |= (j == 0u) ? (mp_digit)(byte & odd_nail_mask) : (mp_digit)byte;
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40 rop->used += 1;
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41 }
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42 }
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43
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44 mp_clamp(rop);
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45
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46 return MP_OKAY;
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47 }
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48
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49 #endif