From f838f00c0469cd07e8867ea6ac4f067dc2c6f2de Mon Sep 17 00:00:00 2001
From: Evan Husted <gr33m11@gmail.com>
Date: Sat, 7 Dec 2024 04:30:04 -0600
Subject: [PATCH] HLE: extract custom NACP data functionality into a static
 helper for generic reuse elsewhere, and clarify magic numbers.

---
 src/Ryujinx.HLE/StructHelpers.cs              | 37 +++++++++++++++++++
 .../UI/Views/Main/MainMenuBarView.axaml.cs    | 31 ++++++----------
 2 files changed, 48 insertions(+), 20 deletions(-)
 create mode 100644 src/Ryujinx.HLE/StructHelpers.cs

diff --git a/src/Ryujinx.HLE/StructHelpers.cs b/src/Ryujinx.HLE/StructHelpers.cs
new file mode 100644
index 000000000..6e6af8cea
--- /dev/null
+++ b/src/Ryujinx.HLE/StructHelpers.cs
@@ -0,0 +1,37 @@
+using LibHac.Common;
+using LibHac.Ns;
+using System;
+using System.Text;
+
+namespace Ryujinx.HLE
+{
+    public static class StructHelpers
+    {
+        public static BlitStruct<ApplicationControlProperty> CreateCustomNacpData(string name, string version)
+        {
+            // https://switchbrew.org/wiki/NACP
+            const int OffsetOfDisplayVersion = 0x3060;
+            
+            // https://switchbrew.org/wiki/NACP#ApplicationTitle
+            const int TotalApplicationTitles = 0x10;
+            const int SizeOfApplicationTitle = 0x300;
+            const int OffsetOfApplicationPublisherStrings = 0x200;
+            
+            
+            var nacpData = new BlitStruct<ApplicationControlProperty>(1);
+
+            // name and publisher buffer
+            // repeat once for each locale (the ApplicationControlProperty has 16 locales)
+            for (int i = 0; i < TotalApplicationTitles; i++)
+            {
+                Encoding.ASCII.GetBytes(name).AsSpan().CopyTo(nacpData.ByteSpan[(i * SizeOfApplicationTitle)..]);
+                "Ryujinx"u8.CopyTo(nacpData.ByteSpan[(i * SizeOfApplicationTitle + OffsetOfApplicationPublisherStrings)..]);
+            }
+            
+            // version buffer
+            Encoding.ASCII.GetBytes(version).AsSpan().CopyTo(nacpData.ByteSpan[OffsetOfDisplayVersion..]);
+
+            return nacpData;
+        }
+    }
+}
diff --git a/src/Ryujinx/UI/Views/Main/MainMenuBarView.axaml.cs b/src/Ryujinx/UI/Views/Main/MainMenuBarView.axaml.cs
index 94f5cf9d3..ffe9b066c 100644
--- a/src/Ryujinx/UI/Views/Main/MainMenuBarView.axaml.cs
+++ b/src/Ryujinx/UI/Views/Main/MainMenuBarView.axaml.cs
@@ -13,6 +13,7 @@ using Ryujinx.Ava.UI.ViewModels;
 using Ryujinx.Ava.UI.Windows;
 using Ryujinx.Common;
 using Ryujinx.Common.Utilities;
+using Ryujinx.HLE;
 using Ryujinx.UI.App.Common;
 using Ryujinx.UI.Common;
 using Ryujinx.UI.Common.Configuration;
@@ -126,32 +127,22 @@ namespace Ryujinx.Ava.UI.Views.Main
 
         public async void OpenMiiApplet(object sender, RoutedEventArgs e)
         {
-            const string name = "miiEdit";
-            const ulong programId = 0x0100000000001009;
-            string contentPath = ViewModel.ContentManager.GetInstalledContentPath(programId, StorageId.BuiltInSystem, NcaContentType.Program);
+            const string AppletName = "miiEdit";
+            const ulong AppletProgramId = 0x0100000000001009;
+            const string AppletVersion = "1.0.0";
+            
+            string contentPath = ViewModel.ContentManager.GetInstalledContentPath(AppletProgramId, StorageId.BuiltInSystem, NcaContentType.Program);
 
             if (!string.IsNullOrEmpty(contentPath))
             {
                 ApplicationData applicationData = new()
                 {
-                    Name = name,
-                    Id = programId,
-                    Path = contentPath,
+                    Name = AppletName,
+                    Id = AppletProgramId,
+                    Path = contentPath
                 };
-
-                string version = "1.0.0";
-                var nacpData = new BlitStruct<ApplicationControlProperty>(1);
-
-                //version buffer
-                Encoding.ASCII.GetBytes(version).AsSpan().CopyTo(nacpData.ByteSpan.Slice(0x3060));
-
-                //name and distributor buffer
-                //repeat once for each locale (the ApplicationControlProperty has 16 locales)
-                for (int i = 0; i < 0x10; i++)
-                {
-                    Encoding.ASCII.GetBytes(name).AsSpan().CopyTo(nacpData.ByteSpan.Slice(i * 0x300));
-                    "Ryujinx"u8.ToArray().AsSpan().CopyTo(nacpData.ByteSpan.Slice(i * 0x300 + 0x200));
-                }
+                
+                var nacpData = StructHelpers.CreateCustomNacpData(AppletName, AppletVersion);
 
                 await ViewModel.LoadApplication(applicationData, ViewModel.IsFullScreen || ViewModel.StartGamesInFullscreen, nacpData);
             }