wabbajack/Wabbajack.DTOs/Texture/PHash.cs

using System.Data;
using System.IO;
using Wabbajack.Hashing.xxHash64;

namespace Wabbajack.DTOs.Texture
{
    public struct PHash
    {
        public const int SIZE = 40;
        private readonly int _hash;

        public byte[] Data { get; }

        public PHash(byte[] data)
        {
            Data = data;
            if (Data.Length != SIZE)
                throw new DataException();

            long h = 0;
            h |= Data[0];
            h <<= 8;
            h |= Data[1];
            h <<= 8;
            h |= Data[2];
            h <<= 8;
            h |= Data[3];
            h <<= 8;
            _hash = (int)h;
        }

        public static PHash FromBase64(string base64)
        {
            var data = base64.FromBase64();
            if (data.Length != SIZE)
                throw new DataException();
            return new PHash(data);
        }

        public static PHash Read(BinaryReader br)
        {
            return new PHash(br.ReadBytes(SIZE));
        }

        public void Write(BinaryWriter br)
        {
            if (_hash == 0)
                br.Write(new byte[SIZE]);
            else
                br.Write(Data);
        }

        public override string ToString()
        {
            return Data.ToBase64();
        }

        public override int GetHashCode()
        {
            long h = 0;
            h |= Data[0];
            h <<= 8;
            h |= Data[1];
            h <<= 8;
            h |= Data[2];
            h <<= 8;
            h |= Data[3];
            h <<= 8;
            return (int)h;
        }
    }
}