feat: support IRISPCK used by CatSystem Android

It appears that red<=>blue channel swapping is needed for hg3 images contained in this type of archives.

Experimental/CatSystem/ArcIRIS.cs

@@ -0,0 +1,102 @@
+//! \file       ArcIRIS.cs
+//! \date       2026-01-25
+//! \brief      CatSystem for Android resource archive.
+//
+// Copyright (C) 2026 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.Collections.Generic;
+using System.ComponentModel.Composition;
+using System.IO;
+using System.Text;
+using GameRes.Utility;
+
+namespace GameRes.Formats.CatSystem {
+    [Export(typeof(ArchiveFormat))]
+    public class IrisPckOpener : ArchiveFormat {
+        public override string         Tag { get { return "DAT/IRIS"; } }
+        public override string Description { get { return "CatSystem for Android resource archive"; } }
+        public override uint     Signature { get { return 0x53495249; } } // 'IRISPCK'
+        public override bool  IsHierarchic { get { return true; } }
+        public override bool      CanWrite { get { return false; } }
+
+        public override ArcFile TryOpen(ArcView file) {
+            if (!file.View.AsciiEqual(4, "PCK"))
+                return null;
+
+            uint offset = 0x18;
+            var dir = new List<Entry>();
+            var name_buffer = new StringBuilder();
+
+            while (offset < file.MaxOffset) {
+                offset += 8;
+                uint name_length = file.View.ReadUInt32(offset);
+
+                offset += 8;
+                name_buffer.Clear();
+                for (int i = 0; i < name_length; i += 2) {
+                    char c = (char)file.View.ReadUInt16(offset + i);
+                    if (c == 0)
+                        break;
+                    name_buffer.Append(c);
+                }
+                var dirname = name_buffer.ToString().Replace("/", "\\");
+                offset += name_length;
+
+                offset += 4;
+                int count = (int)file.View.ReadUInt32(offset);
+                var dir_inner = new List<Entry>(count);
+
+                offset += 0xC;
+                uint prev = 0;
+                for (int i = 0; i < count; i++) {
+                    offset += 8;
+                    uint size = file.View.ReadUInt32(offset);
+                    uint padded_size = file.View.ReadUInt32(offset + 4);
+                    name_length = file.View.ReadUInt32(offset + 8);
+                    offset += 0x18;
+                    name_buffer.Clear();
+                    for (int j = 0; j < name_length; j += 2) {
+                        char c = (char)file.View.ReadUInt16(offset + j);
+                        if (c == 0)
+                            break;
+                        name_buffer.Append(c);
+                    }
+                    var basename = name_buffer.ToString();
+                    var entry = Create<Entry>(Path.Combine(dirname, basename));
+                    entry.Offset = prev;
+                    entry.Size = size;
+                    prev += padded_size;
+                    offset += name_length;
+                    dir_inner.Add(entry);
+                }
+
+                for (int i = 0; i < count; i++) {
+                    dir_inner[i].Offset += offset;
+                }
+                offset += prev;
+                dir.AddRange(dir_inner);
+            }
+
+            return new ArcFile(file, this, dir);
+        }
+    }
+}

Experimental/Experimental.csproj

@@ -149,6 +149,7 @@
   <ItemGroup>
     <Compile Include="Artemis\ImageIPT.cs" />
     <Compile Include="Cabinet\ArcCAB.cs" />
+    <Compile Include="CatSystem\ArcIRIS.cs" />
     <Compile Include="CellWorks\ArcDB.cs" />
     <Compile Include="Artemis\GplexBuffers.cs" />
     <Compile Include="Microsoft\ArcEXE.cs" />