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41 lines
1.1 KiB
41 lines
1.1 KiB
10 years ago
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// Copyright (c) 2012-2013 The Cryptonote developers
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// Distributed under the MIT/X11 software license, see the accompanying
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// file COPYING or http://www.opensource.org/licenses/mit-license.php.
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#include <alloca.h>
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#include <assert.h>
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#include <stddef.h>
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#include <string.h>
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#include "hash-ops.h"
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void tree_hash(const char (*hashes)[HASH_SIZE], size_t count, char *root_hash) {
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assert(count > 0);
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if (count == 1) {
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memcpy(root_hash, hashes, HASH_SIZE);
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} else if (count == 2) {
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cn_fast_hash(hashes, 2 * HASH_SIZE, root_hash);
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} else {
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size_t i, j;
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size_t cnt = count - 1;
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char (*ints)[HASH_SIZE];
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for (i = 1; i < sizeof(size_t); i <<= 1) {
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cnt |= cnt >> i;
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}
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cnt &= ~(cnt >> 1);
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ints = alloca(cnt * HASH_SIZE);
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memcpy(ints, hashes, (2 * cnt - count) * HASH_SIZE);
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for (i = 2 * cnt - count, j = 2 * cnt - count; j < cnt; i += 2, ++j) {
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cn_fast_hash(hashes[i], 64, ints[j]);
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}
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assert(i == count);
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while (cnt > 2) {
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cnt >>= 1;
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for (i = 0, j = 0; j < cnt; i += 2, ++j) {
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cn_fast_hash(ints[i], 64, ints[j]);
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}
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}
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cn_fast_hash(ints[0], 64, root_hash);
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}
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}
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