ps12exe

0.6.11

src/programFrames/GzipWrapper.cs

using System;
using System.IO;
using Ps12exe.Gzip.Internal;
 
// Compile-time only: managed 7-Zip Deflate port with a fixed gzip container.
public static class GzipPackCodec
{
    private static readonly uint[] CrcTable = CreateCrcTable();
    private static uint[] CreateCrcTable()
    {
        uint[] table = new uint[256];
        for (uint i = 0; i < 256; i++)
        {
            uint crc = i;
            for (int bit = 0; bit < 8; bit++)
                crc = (crc >> 1) ^ ((crc & 1) != 0 ? 0xedb88320U : 0U);
            table[i] = crc;
        }
        return table;
    }
    public static byte[] Compress(byte[] data)
    {
        if (data == null) throw new ArgumentNullException("data");
        byte[] body = DeflateEncoder.Encode(data);
        using (MemoryStream output = new MemoryStream())
        {
            // MTIME=0, no filename, XFL=2, OS=255.
            byte[] header = {31,139,8,0,0,0,0,0,2,255};
            output.Write(header, 0, header.Length);
            output.Write(body, 0, body.Length);
            uint crc = 0xffffffffU;
            for (int i = 0; i < data.Length; i++)
                crc = CrcTable[(crc ^ data[i]) & 255] ^ (crc >> 8);
            using (BinaryWriter trailer = new BinaryWriter(output))
            {
                trailer.Write(crc ^ 0xffffffffU);
                trailer.Write((uint)data.Length);
                return output.ToArray();
            }
        }
    }
}