Aaru/DiscImageChef.Helpers/CountBits.cs

// /***************************************************************************
// The Disc Image Chef
// ----------------------------------------------------------------------------
//
// Filename       : CountBits.cs
// Author(s)      : Natalia Portillo <claunia@claunia.com>
//
// Component      : Helpers.
//
// --[ Description ] ----------------------------------------------------------
//
//     Counts bits in a number.
//
// --[ License ] --------------------------------------------------------------
//
//     This library is free software; you can redistribute it and/or modify
//     it under the terms of the GNU Lesser General Public License as
//     published by the Free Software Foundation; either version 2.1 of the
//     License, or (at your option) any later version.
//
//     This library 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
//     Lesser General Public License for more details.
//
//     You should have received a copy of the GNU Lesser General Public
//     License along with this library; if not, see <http://www.gnu.org/licenses/>.
//
// ----------------------------------------------------------------------------
// Copyright © 2011-2019 Natalia Portillo
// ****************************************************************************/

namespace DiscImageChef.Helpers
{
    public static class CountBits
    {
        /// <summary>
        ///     Counts the number of bits set to <c>true</c> in a number
        /// </summary>
        /// <param name="number">Number</param>
        /// <returns>Bits set to <c>true</c></returns>
        public static int Count(uint number)
        {
            number = number - ((number >> 1) & 0x55555555);
            number = (number                 & 0x33333333) + ((number >> 2) & 0x33333333);
            return (int)((((number + (number >> 4)) & 0x0F0F0F0F) * 0x01010101) >> 24);
        }
    }
}