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https://github.com/crskycode/GARbro.git
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112 lines
3.7 KiB
C#
112 lines
3.7 KiB
C#
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//! \file ArcSteinsGate.cs
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//! \date Thu Jul 24 23:36:01 2014
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//! \brief Nitro+ Steins;Gate archive implementation.
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//
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using System.IO;
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using System.Text;
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using System.Collections.Generic;
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using System.ComponentModel.Composition;
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using GameRes.Formats.Strings;
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using GameRes.Utility;
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namespace GameRes.Formats
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{
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[Export(typeof(ArchiveFormat))]
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public class NpaSteinsGateOpener : ArchiveFormat
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{
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public override string Tag { get { return "NPA"; } }
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public override string Description { get { return arcStrings.NPASteinsGateDescription; } }
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public override uint Signature { get { return 0; } }
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public override bool IsHierarchic { get { return true; } }
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internal static readonly byte[] KeyString = {
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'B'^0xff, 'U'^0xff, 'C'^0xff, 'K'^0xff,
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'T'^0xff, 'I'^0xff, 'C'^0xff, 'K'^0xff
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};
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public override ArcFile TryOpen (ArcView file)
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{
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int index_size = file.View.ReadInt32 (0);
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if (index_size < 0x14 || index_size >= file.MaxOffset || index_size > 0xffffff)
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return null;
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var stream = new SteinsGateEncryptedStream (file, 4, (uint)index_size);
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using (var header = new BinaryReader (stream, Encoding.Unicode))
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{
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int entry_count = header.ReadInt32();
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if (entry_count <= 0)
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return null;
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int average_entry_size = index_size / entry_count;
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if (average_entry_size < 0x11)
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return null;
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var dir = new List<Entry> ((int)entry_count);
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for (uint i = 0; i < entry_count; ++i)
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{
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int name_length = header.ReadInt32();
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if (name_length+0x10 > index_size)
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return null;
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string filename = new string (header.ReadChars (name_length/2));
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var entry = FormatCatalog.Instance.CreateEntry (filename);
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entry.Size = header.ReadUInt32();
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entry.Offset = header.ReadInt64();
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if (!entry.CheckPlacement (file.MaxOffset))
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return null;
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dir.Add (entry);
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index_size -= name_length+0x10;
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}
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return new ArcFile (file, this, dir);
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}
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}
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public override Stream OpenEntry (ArcFile arc, Entry entry)
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{
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return new SteinsGateEncryptedStream (arc.File, entry.Offset, entry.Size);
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}
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internal void Encrypt (byte[] buffer, int offset, int count)
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{
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for (int i = 0; i < count; ++i)
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{
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buffer[offset+i] ^= KeyString[i & 7];
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}
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}
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}
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public class SteinsGateEncryptedStream : ArcView.ArcStream
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{
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public SteinsGateEncryptedStream (ArcView file, long offset, uint size)
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: base (file, offset, size)
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{
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}
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public override int Read (byte[] buffer, int offset, int count)
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{
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int position = (int)Position & 7;
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int read = base.Read (buffer, offset, count);
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if (read > 0)
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{
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for (int i = 0; i < read; ++i)
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{
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buffer[offset+i] ^= NpaSteinsGateOpener.KeyString[(position+i)&7];
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}
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}
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return read;
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}
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public override int ReadByte ()
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{
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int position = (int)Position & 7;
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int b = base.ReadByte();
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if (-1 != b)
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{
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b ^= NpaSteinsGateOpener.KeyString[position];
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}
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return b;
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}
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}
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}
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