From f452605e547d09e345dead021dddf43d843e92aa Mon Sep 17 00:00:00 2001
From: morkt <morkt@users.noreply.github.com>
Date: Mon, 25 Feb 2019 12:54:18 +0400
Subject: [PATCH] implemented NPF archives.

---
 ArcFormats/Nonono/ArcNPF.cs | 137 ++++++++++++++++++++++++++++++++++++
 1 file changed, 137 insertions(+)
 create mode 100644 ArcFormats/Nonono/ArcNPF.cs

diff --git a/ArcFormats/Nonono/ArcNPF.cs b/ArcFormats/Nonono/ArcNPF.cs
new file mode 100644
index 00000000..b7e690c9
--- /dev/null
+++ b/ArcFormats/Nonono/ArcNPF.cs
@@ -0,0 +1,137 @@
+//! \file       ArcNPF.cs
+//! \date       2019 Feb 02
+//! \brief      NGS engine resource archive.
+//
+// Copyright (C) 2019 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.IO;
+
+namespace GameRes.Formats.Nonono
+{
+    internal class NpfEntry : Entry
+    {
+        public int  Seed;
+    }
+
+    [Export(typeof(ArchiveFormat))]
+    public class NpfOpener : ArchiveFormat
+    {
+        public override string         Tag { get { return "NPF"; } }
+        public override string Description { get { return "NGS engine resource archive"; } }
+        public override uint     Signature { get { return 0x4B434150; } } // 'PACK'
+        public override bool  IsHierarchic { get { return true; } }
+        public override bool      CanWrite { get { return false; } }
+
+        const int DefaultSeed = 0x46415420; // 'FAT '
+
+        public override ArcFile TryOpen (ArcView file)
+        {
+            if (file.View.ReadInt32 (4) != 4 || file.View.ReadInt32 (8) != 1)
+                return null;
+            var header = file.View.ReadBytes (12, 20);
+            var rnd = new RandomGenerator (DefaultSeed);
+            Decrypt (header, 0, header.Length, rnd);
+            if (!header.AsciiEqual ("FAT "))
+                return null;
+            int count = header.ToInt32 (8);
+            if (!IsSaneCount (count))
+                return null;
+            rnd.SRand (count);
+            var index = file.View.ReadBytes (0x20, 20 * (uint)count);
+            Decrypt (index, 0, index.Length, rnd);
+            int pos = 0;
+            int name_pos = 0x20 + 20 * count;
+            var dir = new List<Entry> (count);
+            var name_buffer = new byte[0x100];
+            for (int i = 0; i < count; ++i)
+            {
+                int name_length = index.ToInt32 (pos+12);
+                if (name_length <= 0 || name_length > name_buffer.Length)
+                    return null;
+                file.View.Read (name_pos, name_buffer, 0, (uint)name_length);
+                int seed = index.ToInt32 (pos+8);
+                rnd.SRand (seed);
+                Decrypt (name_buffer, 0, name_length, rnd);
+                var name = Encodings.cp932.GetString (name_buffer, 0, name_length);
+                var entry = Create<NpfEntry> (name);
+                entry.Offset = index.ToUInt32 (pos+4);
+                entry.Size   = index.ToUInt32 (pos+16);
+                if (!entry.CheckPlacement (file.MaxOffset))
+                    return null;
+                entry.Seed = seed;
+                dir.Add (entry);
+                pos += 20;
+                name_pos += name_length;
+            }
+            return new ArcFile (file, this, dir);
+        }
+
+        public override Stream OpenEntry (ArcFile arc, Entry entry)
+        {
+            var nent = entry as NpfEntry;
+            if (null == nent)
+                return base.OpenEntry (arc, entry);
+            var data = arc.File.View.ReadBytes (entry.Offset, entry.Size);
+            var rnd = new RandomGenerator (nent.Seed);
+            Decrypt (data, 0, data.Length, rnd);
+            return new BinMemoryStream (data, entry.Name);
+        }
+
+        internal void Decrypt (byte[] data, int pos, int count, RandomGenerator rnd)
+        {
+            for (int i = 0; i < count; ++i)
+                data[pos + i] ^= (byte)rnd.Rand();
+        }
+    }
+
+    internal class RandomGenerator
+    {
+        int      m_seed;
+
+        const int DefaultSeed = 0x67895;
+
+        public RandomGenerator (int seed = DefaultSeed)
+        {
+            SRand (seed);
+        }
+
+        public void SRand (int seed)
+        {
+            m_seed = seed;
+            for (int i = 0; i < 32; ++i)
+            {
+                Rand();
+            }
+        }
+
+        public int Rand ()
+        {
+            m_seed ^= 0x65AC9365;
+            m_seed ^= (((m_seed >> 1) ^ m_seed) >> 3)
+                    ^ (((m_seed << 1) ^ m_seed) << 3);
+            return m_seed;
+        }
+    }
+}