RandomWOW/src/blake2_generator.cpp

/*
Copyright (c) 2019 tevador

This file is part of RandomX.

RandomX 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, either version 3 of the License, or
(at your option) any later version.

RandomX 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 RandomX.  If not, see<http://www.gnu.org/licenses/>.
*/

#include <stddef.h>
#include "blake2/blake2.h"
#include "blake2/endian.h"
#include "blake2_generator.hpp"

namespace randomx {

	constexpr int maxSeedSize = 60;

	Blake2Generator::Blake2Generator(const void* seed, size_t seedSize, int nonce) : dataIndex(sizeof(data)) {
		memset(data, 0, sizeof(data));
		memcpy(data, seed, seedSize > maxSeedSize ? maxSeedSize : seedSize);
		store32(&data[maxSeedSize], nonce);
	}

	uint8_t Blake2Generator::getByte() {
		checkData(1);
		return data[dataIndex++];
	}

	uint32_t Blake2Generator::getInt32() {
		checkData(4);
		auto ret = load32(&data[dataIndex]);
		dataIndex += 4;
		return ret;
	}

	void Blake2Generator::checkData(const size_t bytesNeeded) {
		if (dataIndex + bytesNeeded > sizeof(data)) {
			blake2b(data, sizeof(data), data, sizeof(data), nullptr, 0);
			dataIndex = 0;
		}
	}
}