siphash.h

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// Copyright (c) 2016-present The Bitcoin Core developers
// Distributed under the MIT software license, see the accompanying
// file COPYING or http://www.opensource.org/licenses/mit-license.php.

#ifndef BITCOIN_CRYPTO_SIPHASH_H
#define BITCOIN_CRYPTO_SIPHASH_H

#include <array>
#include <cstdint>
#include <span>

class uint256;

class SipHashState
{
    static constexpr uint64_t C0{0x736f6d6570736575ULL}, C1{0x646f72616e646f6dULL}, C2{0x6c7967656e657261ULL}, C3{0x7465646279746573ULL};

public:
    explicit SipHashState(uint64_t k0, uint64_t k1) noexcept : v{C0 ^ k0, C1 ^ k1, C2 ^ k0, C3 ^ k1} {}

    std::array<uint64_t, 4> v{};
};

class CSipHasher
{
    SipHashState m_state;
    uint64_t m_tmp{0};
    uint8_t m_count{0}; 

public:
    CSipHasher(uint64_t k0, uint64_t k1);
    CSipHasher& Write(uint64_t data);
    CSipHasher& Write(std::span<const unsigned char> data);
    uint64_t Finalize() const;
};

class PresaltedSipHasher
{
    const SipHashState m_state;

public:
    explicit PresaltedSipHasher(uint64_t k0, uint64_t k1) noexcept : m_state{k0, k1} {}

    uint64_t operator()(const uint256& val) const noexcept;

    uint64_t operator()(const uint256& val, uint32_t extra) const noexcept;
};

#endif // BITCOIN_CRYPTO_SIPHASH_H