126 lines
3.6 KiB
C
126 lines
3.6 KiB
C
// Copyright (c) 2012-2014, The CryptoNote developers, The Bytecoin developers
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//
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// This file is part of Bytecoin.
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//
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// Bytecoin is free software: you can redistribute it and/or modify
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// it under the terms of the GNU Lesser General Public License as published by
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// the Free Software Foundation, either version 3 of the License, or
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// (at your option) any later version.
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//
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// Bytecoin is distributed in the hope that it will be useful,
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// but WITHOUT ANY WARRANTY; without even the implied warranty of
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// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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// GNU Lesser General Public License for more details.
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//
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// You should have received a copy of the GNU Lesser General Public License
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// along with Bytecoin. If not, see <http://www.gnu.org/licenses/>.
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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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size_t tree_depth(size_t count) {
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size_t i;
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size_t depth = 0;
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assert(count > 0);
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for (i = sizeof(size_t) << 2; i > 0; i >>= 1) {
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if (count >> i > 0) {
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count >>= i;
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depth += i;
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}
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}
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return depth;
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}
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void tree_branch(const char (*hashes)[HASH_SIZE], size_t count, char (*branch)[HASH_SIZE]) {
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size_t i, j;
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size_t cnt = 1;
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size_t depth = 0;
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char (*ints)[HASH_SIZE];
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assert(count > 0);
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for (i = sizeof(size_t) << 2; i > 0; i >>= 1) {
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if (cnt << i <= count) {
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cnt <<= i;
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depth += i;
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}
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}
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assert(cnt == 1ULL << depth);
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assert(depth == tree_depth(count));
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ints = alloca((cnt - 1) * HASH_SIZE);
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memcpy(ints, hashes + 1, (2 * cnt - count - 1) * HASH_SIZE);
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for (i = 2 * cnt - count, j = 2 * cnt - count - 1; j < cnt - 1; i += 2, ++j) {
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cn_fast_hash(hashes[i], 2 * HASH_SIZE, ints[j]);
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}
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assert(i == count);
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while (depth > 0) {
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assert(cnt == 1ULL << depth);
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cnt >>= 1;
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--depth;
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memcpy(branch[depth], ints[0], HASH_SIZE);
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for (i = 1, j = 0; j < cnt - 1; i += 2, ++j) {
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cn_fast_hash(ints[i], 2 * HASH_SIZE, ints[j]);
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}
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}
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}
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void tree_hash_from_branch(const char (*branch)[HASH_SIZE], size_t depth, const char *leaf, const void *path, char *root_hash) {
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if (depth == 0) {
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memcpy(root_hash, leaf, HASH_SIZE);
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} else {
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char buffer[2][HASH_SIZE];
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int from_leaf = 1;
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char *leaf_path, *branch_path;
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while (depth > 0) {
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--depth;
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if (path && (((const char *) path)[depth >> 3] & (1 << (depth & 7))) != 0) {
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leaf_path = buffer[1];
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branch_path = buffer[0];
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} else {
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leaf_path = buffer[0];
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branch_path = buffer[1];
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}
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if (from_leaf) {
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memcpy(leaf_path, leaf, HASH_SIZE);
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from_leaf = 0;
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} else {
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cn_fast_hash(buffer, 2 * HASH_SIZE, leaf_path);
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}
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memcpy(branch_path, branch[depth], HASH_SIZE);
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}
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cn_fast_hash(buffer, 2 * HASH_SIZE, root_hash);
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}
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}
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