lookup-utils.h

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// Hoover Chess Utilities / PGN reader
// Copyright (C) 2025  Sami Kiminki
//
// 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, either version 3 of the License, or
// (at your option) any later version.
//
// 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 <https://www.gnu.org/licenses/>.
 
#ifndef HOOVER_CHESS_UTILS__PGN_READER__LOOKUP_UTILS_H_INCLUDED
#define HOOVER_CHESS_UTILS__PGN_READER__LOOKUP_UTILS_H_INCLUDED
 
#include "chessboard-types.h"
 
#include <array>
#include <cstdint>
 
 
namespace hoover_chess_utils::pgn_reader
{
 
 
 
 
template <typename U64Type>
inline const U64Type &turnSpecificLookup(const std::array<U64Type, 2U> &array, Color turn) noexcept
{
    static_assert(sizeof(U64Type) == 8U);
    static_assert(Color::WHITE == Color { 0U });
    static_assert(Color::BLACK == Color { 8U });
 
    assert(turn == Color::WHITE || turn == Color::BLACK);
 
    const std::uint8_t *ptr { std::bit_cast<const std::uint8_t *>(array.data()) };
    const U64Type *ptrAdjusted { std::bit_cast<const U64Type *>(ptr + static_cast<std::ptrdiff_t>(turn)) };
    return *ptrAdjusted;
}
 
template <typename U64Type, std::size_t N>
inline const U64Type &turnSpecificArrayLookup(
    const std::array<std::array<U64Type, 2U>, N> &array, std::size_t i, Color turn) noexcept
{
    static_assert(sizeof(U64Type) == 8U);
    static_assert(Color::WHITE == Color { 0U });
    static_assert(Color::BLACK == Color { 8U });
 
    assert(turn == Color::WHITE || turn == Color::BLACK);
    assert(i < N);
 
    const std::uint8_t *ptr { std::bit_cast<const std::uint8_t *>(array.data()) };
    const U64Type *ptrAdjusted {
        std::bit_cast<const U64Type *>(
            ptr + static_cast<std::ptrdiff_t>(turn) + 16U * i) };
    return *ptrAdjusted;
}
 
 
 
 
}
 
#endif