checksum.hpp

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// -------------------------------------------------------//
//
// SHAMROCK code for hydrodynamics
// Copyright (c) 2021-2026 Timothée David--Cléris <tim.shamrock@proton.me>
// SPDX-License-Identifier: CeCILL Free Software License Agreement v2.1
// Shamrock is licensed under the CeCILL 2.1 License, see LICENSE for more information
//
// -------------------------------------------------------//
 
#pragma once

 
#include "shambase/aliases_int.hpp"
#include <cstddef>
 
namespace shambase {

    inline u64 fnv1a_hash(const char *data, size_t size) {
        constexpr u64 fnv_offset_basis = 14695981039346656037ULL;
        constexpr u64 fnv_prime        = 1099511628211ULL;
 
        u64 hash = fnv_offset_basis;
        for (size_t i = 0; i < size; ++i) {
            hash ^= static_cast<u64>(static_cast<unsigned char>(data[i]));
            hash *= fnv_prime;
        }
        return hash;
    }
 
} // namespace shambase