PKHeX/PKHeX.Core/Util/FlagUtil.cs

namespace PKHeX.Core
{
    /// <summary>
    /// Utility logic for dealing with bitflags in a byte array.
    /// </summary>
    public static class FlagUtil
    {
        public static bool GetFlag(byte[] arr, int offset, int bitIndex)
        {
            bitIndex &= 7; // ensure bit access is 0-7
            return (arr[offset] >> bitIndex & 1) != 0;
        }

        public static void SetFlag(byte[] arr, int offset, int bitIndex, bool value)
        {
            bitIndex &= 7; // ensure bit access is 0-7
            arr[offset] &= (byte)~(1 << bitIndex);
            arr[offset] |= (byte)((value ? 1 : 0) << bitIndex);
        }
    }
}