(AFA): implemented archives version 3 (#216)

ArcFormats/AliceSoft/ArcAFA.cs

@@ -2,7 +2,7 @@
 //! \date       Mon Apr 25 18:18:57 2016
 //! \brief      AliceSoft System 4 engine resource archive.
 //
-// Copyright (C) 2016 by morkt
+// Copyright (C) 2016-2018 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
@@ -43,7 +43,7 @@ namespace GameRes.Formats.AliceSoft
         public override ArcFile TryOpen (ArcView file)
         {
             if (!file.View.AsciiEqual (8, "AlicArch"))
-                return null;
+                return TryOpenV3 (file);
             if (!file.View.AsciiEqual (0x1C, "INFO"))
                 return null;
             int version = file.View.ReadInt32 (0x10);
@@ -86,6 +86,18 @@ namespace GameRes.Formats.AliceSoft
             }
         }
 
+        internal ArcFile TryOpenV3 (ArcView file)
+        {
+            if (file.View.ReadInt32 (8) != 3)
+                return null;
+            uint index_size = file.View.ReadUInt32 (4);
+            var index = new AfaIndexReader (file, index_size);
+            var dir = index.Read();
+            if (null == dir || 0 == dir.Count)
+                return null;
+            return new ArcFile (file, this, dir);
+        }
+
         static readonly byte[] AffKey = {
             0xC8, 0xBB, 0x8F, 0xB7, 0xED, 0x43, 0x99, 0x4A,
             0xA2, 0x7E, 0x5B, 0xB0, 0x68, 0x18, 0xF8, 0x88
@@ -106,4 +118,195 @@ namespace GameRes.Formats.AliceSoft
             return new PrefixStream (prefix, rest);
         }
     }
+
+    internal sealed class AfaIndexReader
+    {
+        ArcView         m_file;
+        uint            m_data_offset;
+        byte[]          m_dict;
+
+        public AfaIndexReader (ArcView file, uint index_size)
+        {
+            m_file = file;
+            m_data_offset = index_size + 8;
+        }
+
+        public List<Entry> Read ()
+        {
+            byte[] packed;
+            using (var input = m_file.CreateStream (12, m_data_offset-12))
+            using (var bits = new MsbBitStream (input))
+            {
+                bits.GetNextBit();
+                m_dict = ReadBytes (bits);
+                if (null == m_dict)
+                    return null;
+                int packed_size   = ReadInt32 (bits);
+                int unpacked_size = ReadInt32 (bits);
+                packed = new byte[packed_size];
+                for (int i = 0; i < packed_size; ++i)
+                {
+                    packed[i] = (byte)bits.GetBits (8);
+                }
+            }
+            using (var bstr = new BinMemoryStream (packed))
+            using (var zstr = new ZLibStream (bstr, CompressionMode.Decompress))
+            using (var index = new MsbBitStream (zstr))
+            {
+                index.GetNextBit();
+                int count = ReadInt32 (index);
+                if (!ArchiveFormat.IsSaneCount (count))
+                    return null;
+                var dir = new List<Entry> (count);
+                for (int i = 0; i < count; ++i)
+                {
+                    if (index.GetBits (2) == -1)
+                        break;
+                    var name_buf = ReadEncryptedChars (index);
+                    if (null == name_buf)
+                        return null;
+                    var name = DecryptString (name_buf, name_buf.Length);
+                    var entry = FormatCatalog.Instance.Create<Entry> (name);
+                    ReadInt32 (index);
+                    ReadInt32 (index);
+                    entry.Offset = (uint)ReadInt32 (index) + m_data_offset;
+                    entry.Size   = (uint)ReadInt32 (index);
+                    if (!entry.CheckPlacement (m_file.MaxOffset))
+                        return null;
+                    dir.Add (entry);
+                }
+                return dir;
+            }
+        }
+
+        byte[] ReadBytes (MsbBitStream input)
+        {
+            int buf_size = ReadInt32 (input);
+            var buf = new byte[buf_size];
+            int dst = 0;
+            var rnd = new RandomGenerator ((uint)buf_size);
+            while (dst < buf_size)
+            {
+                int count = (int)rnd.GetNext() & 3;
+                int skipped = input.GetBits (count + 1);
+                if (-1 == skipped)
+                    return null;
+                rnd.GetNext();
+
+                int v = input.GetBits (8);
+                if (-1 == v)
+                    return null;
+                buf[dst++] = (byte)v;
+            }
+            return buf;
+        }
+
+        ushort[] ReadEncryptedChars (MsbBitStream input)
+        {
+            int buf_size = ReadInt32 (input);
+            var buf = new ushort[buf_size];
+            int dst = 0;
+            var rnd = new RandomGenerator ((uint)buf_size);
+            while (dst < buf_size)
+            {
+                int count = (int)rnd.GetNext() & 3;
+                int skipped = input.GetBits (count + 1);
+                if (-1 == skipped)
+                    return null;
+                rnd.GetNext();
+
+                int lo = input.GetBits (8);
+                int hi = input.GetBits (8);
+                if (-1 == lo || -1 == hi)
+                    return null;
+                buf[dst++] = (ushort)(lo | hi << 8);
+            }
+            return buf;
+        }
+
+        byte[] m_string_buf = new byte[0x100];
+
+        string DecryptString (ushort[] input, int input_length)
+        {
+            if (m_string_buf.Length < input_length)
+                m_string_buf = new byte[input_length];
+            for (int i = 0; i < input_length; ++i)
+            {
+                m_string_buf[i] = (byte)(m_dict[input[i]] ^ 0xA4);
+            }
+            return Encodings.cp932.GetString (m_string_buf, 0, input_length);
+        }
+
+        static int ReadInt32 (MsbBitStream input)
+        {
+            int b0 = input.GetBits (8);
+            int b1 = input.GetBits (8);
+            int b2 = input.GetBits (8);
+            int b3 = input.GetBits (8);
+            return b3 << 24 | b2 << 16 | b1 << 8 | b0;
+        }
+    }
+
+    internal class RandomGenerator
+    {
+        uint[]  m_state = new uint[521];
+        int     m_current;
+
+        public RandomGenerator (uint seed)
+        {
+            Init (seed);
+        }
+
+        public void Init (uint seed)
+        {
+            uint val = 0;
+            for (int i = 0; i < 17; ++i)
+            {
+                for (int j = 0; j < 32; ++j)
+                {
+                    seed = 1566083941u * seed + 1;
+                    val = seed & 0x80000000 | (val >> 1);
+                }
+                m_state[i] = val;
+            }
+            m_state[16] = m_state[15] ^ (m_state[0] >> 9) ^ (m_state[16] << 23);
+            for (int i = 17; i < 521; ++i)
+            {
+                m_state[i] = m_state[i-1] ^ (m_state[i-16] >> 9) ^ (m_state[i-17] << 23);
+            }
+            Shuffle();
+            Shuffle();
+            Shuffle();
+            Shuffle();
+            m_current = -1;
+        }
+
+        public uint GetNext ()
+        {
+            ++m_current;
+            if (m_current >= 521)
+            {
+                Shuffle();
+                m_current = 0;
+            }
+            return m_state[m_current];
+        }
+
+        void Shuffle ()
+        {
+            for (int i = 0; i < 32; i += 4)
+            {
+                m_state[i  ] ^= m_state[i + 489];
+                m_state[i+1] ^= m_state[i + 490];
+                m_state[i+2] ^= m_state[i + 491];
+                m_state[i+3] ^= m_state[i + 492];
+            }
+            for (int i = 32; i < 521; i += 3)
+            {
+                m_state[i  ] ^= m_state[i - 32];
+                m_state[i+1] ^= m_state[i - 31];
+                m_state[i+2] ^= m_state[i - 30];
+            }
+        }
+    }
 }