PKHeX/PKHeX.Core/Saves/Substructures/Gen5/Encount5.cs

namespace PKHeX.Core
{
    public abstract class Encount5 : SaveBlock
    {
        protected Encount5(SAV5 SAV, int offset) : base(SAV) => Offset = offset;

        public abstract byte SwarmSeed { get; set; }
        public abstract uint SwarmMaxCountModulo { get; }

        public uint SwarmIndex
        {
            get => SwarmSeed % SwarmMaxCountModulo;
            set => SwarmSeed = (byte)(value % SwarmMaxCountModulo);
        }
    }

    public sealed class Encount5BW : Encount5
    {
        public Encount5BW(SAV5BW SAV, int offset) : base(SAV, offset) { }

        public override byte SwarmSeed { get => Data[Offset + 0x30]; set => Data[Offset + 0x30] = value; }
        public override uint SwarmMaxCountModulo => 17;
    }

    public sealed class Encount5B2W2 : Encount5
    {
        public Encount5B2W2(SAV5B2W2 SAV, int offset) : base(SAV, offset) { }

        public override byte SwarmSeed { get => Data[Offset + 0x2C]; set => Data[Offset + 0x2C] = value; }
        public override uint SwarmMaxCountModulo => 19;
    }
}