2014-07-23 13:03:52 +00:00
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// Copyright (c) 2014, The Monero Project
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//
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// All rights reserved.
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//
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// Redistribution and use in source and binary forms, with or without modification, are
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// permitted provided that the following conditions are met:
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//
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// 1. Redistributions of source code must retain the above copyright notice, this list of
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// conditions and the following disclaimer.
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//
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// 2. Redistributions in binary form must reproduce the above copyright notice, this list
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// of conditions and the following disclaimer in the documentation and/or other
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// materials provided with the distribution.
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//
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// 3. Neither the name of the copyright holder nor the names of its contributors may be
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// used to endorse or promote products derived from this software without specific
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// prior written permission.
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//
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// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND ANY
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// EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
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// MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL
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// THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
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// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
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// PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
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// INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
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// STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF
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// THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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//
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// Parts of this file are originally copyright (c) 2012-2013 The Cryptonote developers
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2014-03-03 22:07:58 +00:00
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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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