mariadb-columnstore-engine/utils/common/columnwidth.h

/* Copyright (C) 2020 MariaDB Corporation 

   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 2 of
   the License.

   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, write to the Free Software
   Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston,
   MA 02110-1301, USA. */

#ifndef UTILS_COLWIDTH_H
#define UTILS_COLWIDTH_H

#include "branchpred.h"

namespace utils
{
    const uint8_t MAXLEGACYWIDTH = 8ULL;
    const uint8_t MAXCOLUMNWIDTH = 16ULL;

    inline bool isWide(uint8_t width)
    {
        return width > MAXLEGACYWIDTH;
    }

    inline bool isNarrow(uint8_t width)
    {
        return width <= MAXLEGACYWIDTH;
    }

    /** @brief Map a DECIMAL precision to data width in bytes */
    inline uint8_t widthByPrecision(unsigned p)
    {
        if (LIKELY(p > 18 && p < 39))
            return 16;

        switch (p)
        {
            case 1:
            case 2:
                return 1;

            case 3:
            case 4:
                return 2;

            case 5:
            case 6:
            case 7:
            case 8:
            case 9:
                return 4;
            
            case 10:
            case 11:
            case 12:
            case 13:
            case 14:
            case 15:
            case 16:
            case 17:
            case 18:
                return 8;
            
            default:
            return 16;
        }
    }

    inline uint8_t precisionByWidth(unsigned w)
    {
        switch(w)
        {
            case 16:
                return 38;
            // In case we will support decimals that spans 32 bytes.
            default:
                return 65;
        }
    }


}

#endif // UTILS_COLWIDTH_H