COM3D2.MeidoPhotoStudio/src/MeidoPhotoStudio.Converter/Utility/LZMA.cs

using System.IO;

using SevenZip.Compression.LZMA;

namespace MeidoPhotoStudio.Converter.Utility;

internal static class LZMA
{
    public static MemoryStream Decompress(Stream inStream)
    {
        var outStream = new MemoryStream();
        var properties = new byte[5];

        if (inStream.Read(properties, 0, 5) is not 5)
            throw new("input .lzma is too short");

        var decoder = new Decoder();

        decoder.SetDecoderProperties(properties);

        var outSize = 0L;

        for (var i = 0; i < 8; i++)
        {
            var v = inStream.ReadByte();

            if (v < 0)
                throw new("Can't Read 1");

            outSize |= ((long)(byte)v) << (8 * i);
        }

        var compressedSize = inStream.Length - inStream.Position;

        decoder.Code(inStream, outStream, compressedSize, outSize, null);

        return outStream;
    }
}