diff --git a/ArcFormats/ArcFormats.csproj b/ArcFormats/ArcFormats.csproj
index 5516d519..fe254eaf 100644
--- a/ArcFormats/ArcFormats.csproj
+++ b/ArcFormats/ArcFormats.csproj
@@ -118,6 +118,7 @@
+
diff --git a/ArcFormats/DaiSystem/ArcPAC.cs b/ArcFormats/DaiSystem/ArcPAC.cs
new file mode 100644
index 00000000..b1fe1ee2
--- /dev/null
+++ b/ArcFormats/DaiSystem/ArcPAC.cs
@@ -0,0 +1,204 @@
+//! \file ArcPAC.cs
+//! \date 2018 Jan 11
+//! \brief DAI system resource archive.
+//
+// Copyright (C) 2018 by morkt
+//
+// Permission is hereby granted, free of charge, to any person obtaining a copy
+// of this software and associated documentation files (the "Software"), to
+// deal in the Software without restriction, including without limitation the
+// rights to use, copy, modify, merge, publish, distribute, sublicense, and/or
+// sell copies of the Software, and to permit persons to whom the Software is
+// furnished to do so, subject to the following conditions:
+//
+// The above copyright notice and this permission notice shall be included in
+// all copies or substantial portions of the Software.
+//
+// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
+// FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
+// IN THE SOFTWARE.
+//
+
+using System;
+using System.Collections.Generic;
+using System.ComponentModel.Composition;
+using System.Diagnostics;
+using System.IO;
+using System.Linq;
+using GameRes.Utility;
+
+namespace GameRes.Formats.DaiSystem
+{
+ [Export(typeof(ArchiveFormat))]
+ public class PacOpener : ArchiveFormat
+ {
+ public override string Tag { get { return "PAC/DAI"; } }
+ public override string Description { get { return "DAI system resource archive"; } }
+ public override uint Signature { get { return 0x5F494144; } } // 'DAI_SYSTEM_01000'
+ public override bool IsHierarchic { get { return false; } }
+ public override bool CanWrite { get { return false; } }
+
+ public override ArcFile TryOpen (ArcView file)
+ {
+ if (!file.View.AsciiEqual (4, "SYSTEM_01000"))
+ return null;
+ int count = Binary.BigEndian (file.View.ReadUInt16 (0x10));
+ if (!IsSaneCount (count))
+ return null;
+ uint index_size = Binary.BigEndian (file.View.ReadUInt32 (0x12));
+ var index = file.View.ReadBytes (0x16, index_size);
+ for (int i = 0; i < index.Length; ++i)
+ index[i] -= (byte)(i + 0x28);
+
+ int index_offset = 0;
+ var dir = new List (count);
+ for (int i = 0; i < count; ++i)
+ {
+ int name_end = Array.IndexOf (index, (byte)',', index_offset);
+ if (-1 == name_end)
+ return null;
+ var name = Encodings.cp932.GetString (index, index_offset, name_end - index_offset);
+ index_offset = name_end + 1;
+ var entry = FormatCatalog.Instance.Create (name);
+ entry.Offset = BigEndian.ToUInt32 (index, index_offset);
+ index_offset += 5;
+ dir.Add (entry);
+ }
+ for (int i = 1; i < dir.Count; ++i)
+ {
+ var entry = dir[i-1];
+ entry.Size = (uint)(dir[i].Offset - entry.Offset);
+ if (!entry.CheckPlacement (file.MaxOffset))
+ return null;
+ }
+ dir[dir.Count-1].Size = (uint)(file.MaxOffset - dir[dir.Count-1].Offset);
+ DetectFileTypes (file, dir);
+ return new ArcFile (file, this, dir);
+ }
+
+ void DetectFileTypes (ArcView file, List dir)
+ {
+ foreach (var entry in dir.Where (e => string.IsNullOrEmpty (e.Type)))
+ {
+ uint signature = file.View.ReadUInt32 (entry.Offset);
+ if (0x05304148 == signature)
+ {
+ entry.Type = "image";
+ continue;
+ }
+ else if (0x304148 == (signature & 0xFFFFFF))
+ {
+ uint encryption = file.View.ReadUInt32 (entry.Offset+8);
+ long offset = entry.Offset + 0x10 + (signature >> 24);
+ if (0 != encryption)
+ {
+ if (4 == encryption)
+ {
+ uint bits = Binary.BigEndian (file.View.ReadUInt32 (offset + 8));
+ if (bits > entry.Size)
+ continue;
+ if (file.View.AsciiEqual (offset+12+bits, "BM"))
+ {
+ entry.ChangeType (ImageFormat.Bmp);
+ }
+ else if (file.View.AsciiEqual (entry.Offset+entry.Size-0x12, "TRUEVISION"))
+ {
+ entry.ChangeType (ImageFormat.Tga);
+ }
+ }
+ continue;
+ }
+ signature = file.View.ReadUInt32 (offset);
+ }
+ entry.ChangeType (AutoEntry.DetectFileType (signature));
+ }
+ }
+
+ public override Stream OpenEntry (ArcFile arc, Entry entry)
+ {
+ if (!arc.File.View.AsciiEqual (entry.Offset, "HA0"))
+ return base.OpenEntry (arc, entry);
+ byte header_length = arc.File.View.ReadByte (entry.Offset+3);
+ uint ha0_header_length = 0x10u + header_length;
+ if (ha0_header_length >= entry.Size)
+ return base.OpenEntry (arc, entry);
+ uint unpacked_size = Binary.BigEndian (arc.File.View.ReadUInt32 (entry.Offset+4));
+ uint pattern = arc.File.View.ReadUInt32 (entry.Offset+8);
+ var header = arc.File.View.ReadBytes (entry.Offset+0x10, header_length);
+ var input = arc.File.View.ReadBytes (entry.Offset + ha0_header_length, entry.Size - ha0_header_length);
+ while (pattern != 0)
+ {
+ uint code = pattern >> 24;
+ switch (code)
+ {
+ case 0: break;
+ case 2: input = Decrypt2 (input); break;
+ case 3: input = Decrypt3 (input); break;
+ case 4: input = Unpack4 (input); break;
+ default:
+ Trace.WriteLine (string.Format ("Unknown encryption method ({0})", code), "[DAI_SYSTEM]");
+ return base.OpenEntry (arc, entry);
+ }
+ pattern <<= 8;
+ }
+ return new BinMemoryStream (input, entry.Name);
+ }
+
+ byte[] Decrypt2 (byte[] input)
+ {
+ var output = new byte[input.Length];
+ int src = 0;
+ for (int i = 0; i < 3; ++i)
+ {
+ for (int dst = i; dst < output.Length; dst += 3)
+ output[dst] = input[src++];
+ }
+ return output;
+ }
+
+ byte[] Decrypt3 (byte[] input)
+ {
+ for (int i = 1; i < input.Length; ++i)
+ {
+ input[i] += input[i-1];
+ }
+ return input;
+ }
+
+ byte[] Unpack4 (byte[] input)
+ {
+ int unpacked_size = BigEndian.ToInt32 (input, 0);
+ var output = new byte[unpacked_size];
+ int ctl_bits = BigEndian.ToInt32 (input, 4);
+ int ctl_bytes = BigEndian.ToInt32 (input, 8);
+ int ctl = 12;
+ int src = 12 + ctl_bytes;
+ int dst = 0;
+ int bits = 2;
+ while (dst < output.Length)
+ {
+ bits >>= 1;
+ if (1 == bits)
+ {
+ bits = input[ctl++] | 0x100;
+ }
+ if (0 == (bits & 1))
+ {
+ output[dst++] = input[src++];
+ }
+ else
+ {
+ int offset = input[src++];
+ int count = input[src++];
+ Binary.CopyOverlapped (output, dst-offset, dst, count);
+ dst += count;
+ }
+ }
+ return output;
+ }
+ }
+}