Moved out merkle tree hash code

src/merkle.cpp

@@ -0,0 +1,60 @@
+/*
+ * This file is part of the Monero P2Pool <https://github.com/SChernykh/p2pool>
+ * Copyright (c) 2021-2023 SChernykh <https://github.com/SChernykh>
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, version 3.
+ *
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+ * General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program. If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#include "common.h"
+#include "keccak.h"
+#include "merkle.h"
+
+namespace p2pool {
+
+void merkle_hash(const std::vector<hash>& hashes, hash& root)
+{
+	const size_t count = hashes.size();
+	const uint8_t* h = hashes[0].h;
+
+	if (count == 1) {
+		root = hashes[0];
+	}
+	else if (count == 2) {
+		keccak(h, HASH_SIZE * 2, root.h);
+	}
+	else {
+		size_t cnt = 1;
+		do { cnt <<= 1; } while (cnt <= count);
+		cnt >>= 1;
+
+		std::vector<hash> tmp_ints(cnt);
+
+		const size_t k = cnt * 2 - count;
+		memcpy(tmp_ints.data(), h, k * HASH_SIZE);
+
+		for (size_t i = k, j = k; j < cnt; i += 2, ++j) {
+			keccak(h + i * HASH_SIZE, HASH_SIZE * 2, tmp_ints[j].h);
+		}
+
+		while (cnt > 2) {
+			cnt >>= 1;
+			for (size_t i = 0, j = 0; j < cnt; i += 2, ++j) {
+				keccak(tmp_ints[i].h, HASH_SIZE * 2, tmp_ints[j].h);
+			}
+		}
+
+		keccak(tmp_ints[0].h, HASH_SIZE * 2, root.h);
+	}
+}
+
+} // namespace p2pool