37 lines
925 B
C
37 lines
925 B
C
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#include "tommath_private.h"
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#ifdef MP_HASH_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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#if defined(MP_16BIT)
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#define FNV_1A_INIT ((uint32_t)0x811c9dc5)
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#define FNV_1A_PRIME ((uint32_t)0x01000193)
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#else
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#define FNV_1A_INIT ((uint64_t)0xcbf29ce484222325ULL)
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#define FNV_1A_PRIME ((uint64_t)0x100000001b3ULL)
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#endif
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/* computes hash of mp_int. */
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mp_err mp_hash(mp_int *a, mp_hval *hash)
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{
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int x;
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mp_hval hval = FNV_1A_INIT;
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mp_digit r, mask, shift;
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/* FNV-1a algorithm */
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mask = ((mp_digit)1 << 8) - 1uL;
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shift = (mp_digit)(MP_DIGIT_BIT - 8);
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r = 0;
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for (x = a->used; x --> 0;) {
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mp_digit rr = a->dp[x] & mask;
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hval ^= (mp_hval)(a->dp[x] >> 8) | (r << shift);
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hval *= FNV_1A_PRIME;
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r = rr;
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}
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hval ^= mp_isneg(a) ? (mp_hval)1 : (mp_hval)0;
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*hash = hval * FNV_1A_PRIME;
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return MP_OKAY;
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}
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#endif
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