feat: support compressed and embedded EVB package

There might be a conflict with Experimental/Microsoft/ArcEXE.cs. Maybe add a option later to disable that?

ArcFormats/Enigma/ArcEVB.cs

@@ -29,6 +29,7 @@ using System.IO;
 using System.Linq;
 using System.Text;
 using GameRes.Utility;
+using GameRes.Compression;
 
 namespace GameRes.Formats.Enigma {
     public enum NodeTypes {
@@ -45,14 +46,33 @@ namespace GameRes.Formats.Enigma {
         public override bool  IsHierarchic { get { return true; } }
         public override bool      CanWrite { get { return false; } }
 
+        public EvbPackOpener() {
+            Signatures = new uint[] { 0x425645, 0x905a4d, 0 };
+        }
+
         public override ArcFile TryOpen(ArcView file) {
-            uint index_size = file.View.ReadUInt32(0x40) + 68;
+            uint base_offset = 0;
-            uint index_offset = 0x4F;
+            if (file.View.AsciiEqual(0, "MZ")) {
+                var exe = new ExeFile(file);
+                var sig = new byte[] { 0x45, 0x56, 0x42, 0x00 };
+                if (exe.ContainsSection(".enigma1")) {
+                    var ofs = exe.FindString(exe.Sections[".enigma1"], sig);
+                    if (ofs != -1)
+                        base_offset = (uint)ofs;
+                }
+                if (base_offset == 0)
+                    return null;
+            }
+            else if (!file.View.AsciiEqual(0, "EVB"))
+                return null;
+
+            uint index_size = file.View.ReadUInt32(base_offset + 0x40) + base_offset + 68;
+            uint index_offset = base_offset + 0x4F;
             uint file_offset = index_size;
 
             var dir = new List<Entry>();
             var name_buffer = new StringBuilder();
-            var counts = new List<uint> { file.View.ReadUInt32(0x4C) };
+            var counts = new List<uint> { file.View.ReadUInt32(base_offset + 0x4C) };
             var names = new List<string> { "" };
 
             while (index_offset < index_size - 4) {
@@ -73,12 +93,12 @@ namespace GameRes.Formats.Enigma {
                 index_offset++;
                 counts[counts.Count - 1]--;
                 if (type == NodeTypes.File) {
-                    var entry = Create<Entry>(Path.Combine(names.Concat(new[] { name }).ToArray()));
+                    var entry = Create<PackedEntry>(Path.Combine(names.Concat(new[] { name }).ToArray()));
                     uint unpacked_size = file.View.ReadUInt32(index_offset + 2);
                     uint size = file.View.ReadUInt32(index_offset + 49);
-                    if (unpacked_size != size)
+                    entry.IsPacked = unpacked_size != size;
-                        return null; // packed entry not implemented
                     entry.Offset = file_offset;
+                    entry.UnpackedSize = unpacked_size;
                     entry.Size = size;
                     file_offset += size;
                     if (!entry.CheckPlacement(file.MaxOffset))
@@ -106,5 +126,30 @@ namespace GameRes.Formats.Enigma {
 
             return new ArcFile(file, this, dir);
         }
+
+        public override Stream OpenEntry(ArcFile arc, Entry entry) {
+            var pent = entry as PackedEntry;
+            if (pent.IsPacked) {
+                uint header_size = arc.File.View.ReadUInt32(pent.Offset);
+                uint offset = header_size;
+                Stream input = null;
+
+                for (uint i = 8; i < header_size; i += 12) {
+                    uint chunk_size = arc.File.View.ReadUInt32(pent.Offset + i);
+                    var chunk = new aPLibStream(
+                        arc.File.CreateStream(pent.Offset + offset, chunk_size)
+                    );
+                    if (input != null)
+                        input = new ConcatStream(input, chunk);
+                    else
+                        input = chunk;
+                    offset += chunk_size;
+                }
+
+                return input;
+            }
+            else
+                return arc.File.CreateStream(pent.Offset, pent.Size);
+        }
     }
 }

ArcFormats/aPLibStream.cs

@@ -0,0 +1,188 @@
+//! \file       aPLibStream.cs
+//! \date       2026-01-09
+
+/*
+ * aPLib compression library  -  the smaller the better :)
+ *
+ * C depacker
+ *
+ * Copyright (c) 1998-2014 Joergen Ibsen
+ * All Rights Reserved
+ *
+ * http://www.ibsensoftware.com/
+ */
+
+// C# port by scientificworld
+
+using System;
+using System.Collections.Generic;
+using System.IO;
+
+namespace GameRes.Compression {
+    public sealed class aPLibCoroutine : Decompressor {
+        Stream  m_input;
+        uint    m_tag;
+        uint    m_bitcount;
+
+        public override void Initialize (Stream input) {
+            m_input = input;
+        }
+
+        protected override IEnumerator<int> Unpack () {
+            uint offs, len, R0, LWM;
+
+            var hist = new List<byte>();
+
+            m_bitcount = 0;
+            R0 = uint.MaxValue; // (uint) -1
+            LWM = 0;
+
+            m_buffer[m_pos] = ReadByte();
+            hist.Add(m_buffer[m_pos++]);
+            if (--m_length == 0)
+                yield return m_pos;
+
+            while (true) {
+                if (GetBit() != 0) {
+                    if (GetBit() != 0) {
+                        if (GetBit() != 0) {
+                            offs = 0;
+
+                            for (int i = 0; i < 4; i++) {
+                                offs = (offs << 1) + GetBit();
+                            }
+
+                            if (offs != 0) {
+                                m_buffer[m_pos] = hist[(int)(hist.Count - offs)];
+                            }
+                            else {
+                                m_buffer[m_pos] = 0x00;
+                            }
+                            hist.Add(m_buffer[m_pos++]);
+
+                            LWM = 0;
+                            if (--m_length == 0)
+                                yield return m_pos;
+                        }
+                        else {
+                            offs = (uint)ReadByte();
+
+                            len = 2 + (offs & 0x0001);
+
+                            offs >>= 1;
+
+                            if (offs != 0) {
+                                for (; len != 0; len--) {
+                                    m_buffer[m_pos] = hist[(int)(hist.Count - offs)];
+                                    hist.Add(m_buffer[m_pos++]);
+                                    if (--m_length == 0)
+                                        yield return m_pos;
+                                }
+                            }
+                            else {
+                                yield break;
+                            }
+
+                            R0 = offs;
+                            LWM = 1;
+                        }
+                    }
+                    else {
+                        offs = GetGamma();
+
+                        if ((LWM == 0) && (offs == 2)) {
+                            offs = R0;
+
+                            len = GetGamma();
+
+                            for (; len != 0; len--) {
+                                m_buffer[m_pos] = hist[(int)(hist.Count - offs)];
+                                hist.Add(m_buffer[m_pos++]);
+                                if (--m_length == 0)
+                                    yield return m_pos;
+                            }
+                        }
+                        else {
+                            if (LWM == 0) {
+                                offs -= 3;
+                            }
+                            else {
+                                offs -= 2;
+                            }
+
+                            offs <<= 8;
+                            offs += (uint)ReadByte();
+
+                            len = GetGamma();
+
+                            if (offs >= 32000) {
+                                len++;
+                            }
+                            if (offs >= 1280) {
+                                len++;
+                            }
+                            if (offs < 128) {
+                                len += 2;
+                            }
+
+                            for (; len != 0; len--) {
+                                m_buffer[m_pos] = hist[(int)(hist.Count - offs)];
+                                hist.Add(m_buffer[m_pos++]);
+                                if (--m_length == 0)
+                                    yield return m_pos;
+                            }
+
+                            R0 = offs;
+                        }
+
+                        LWM = 1;
+                    }
+                }
+                else {
+                    m_buffer[m_pos] = ReadByte();
+                    hist.Add(m_buffer[m_pos++]);
+                    LWM = 0;
+                    if (--m_length == 0)
+                        yield return m_pos;
+                }
+            }
+        }
+
+        uint GetBit () {
+            uint bit;
+
+            if (m_bitcount-- == 0) {
+                m_tag = (uint)ReadByte();
+                m_bitcount = 7;
+            }
+            bit = (m_tag >> 7) & 0x01;
+            m_tag <<= 1;
+
+            return bit;
+        }
+
+        uint GetGamma () {
+            uint result = 1;
+
+            do {
+                result = (result << 1) + GetBit();
+            } while (GetBit() != 0);
+
+            return result;
+        }
+
+        byte ReadByte () {
+            int b = m_input.ReadByte();
+            if (b == -1)
+                throw new EndOfStreamException();
+            return (byte)b;
+        }
+    }
+
+    public class aPLibStream : PackedStream<aPLibCoroutine> {
+        public aPLibStream (Stream input, CompressionMode mode = CompressionMode.Decompress, bool leave_open = false) : base (input, leave_open) {
+            if (mode != CompressionMode.Decompress)
+                throw new NotImplementedException ("aPLibStream compression not implemented");
+        }
+    }
+}