Implement INPUTNAME string opcodes

engine/Age.Engine/Hosting/IHost.cs

@@ -31,6 +31,10 @@ public readonly record struct SurfaceRectCopy(
 /// <summary>A synchronous AGE-owned diagnostic prompt after native body/context formatting.</summary>
 public readonly record struct DiagnosticMessage(string Caption, string Text);
 
+/// <summary>AGERc command 10's synchronous full-width text edit request and result.</summary>
+public readonly record struct FullwidthTextEditRequest(string CurrentText, string InitialText);
+public readonly record struct FullwidthTextEditResult(bool Accepted, string Text);
+
 public enum SurfaceBlackFadeDirection
 {
     FromBlack,
@@ -44,6 +48,9 @@ public interface IHost
     /// <summary>Present a modal diagnostic and return only after the user dismisses it.</summary>
     void ShowDiagnosticMessage(DiagnosticMessage message)
         => System.Console.Error.WriteLine($"{message.Caption}: {message.Text}");
+    /// <summary>Present AGERc's modal full-width editor. Cancel preserves CurrentText.</summary>
+    FullwidthTextEditResult EditFullwidthString(FullwidthTextEditRequest request)
+        => new(false, request.CurrentText);
     // Script context is retained for diagnostics/page location; resource operands are universal packed ids.
     void EnterScriptContext(string scriptName) { }
     void ExitScriptContext() { }

engine/Age.Engine/Sys4/Cp932Text.cs

@@ -0,0 +1,98 @@
+using System.Text;
+
+namespace Age.Engine.Sys4;
+
+public enum FullwidthTextValidationError
+{
+    None,
+    TooLong,
+    NonDoubleByteCharacter,
+}
+
+/// <summary>AGE's Japanese-locale byte-string operations used by INPUTNAME.</summary>
+public static class Cp932Text
+{
+    public const int NativeNameByteLimit = 16;
+    private static readonly Encoding NativeEncoding;
+
+    static Cp932Text()
+    {
+        Encoding.RegisterProvider(CodePagesEncodingProvider.Instance);
+        NativeEncoding = Encoding.GetEncoding(932);
+    }
+
+    private static bool IsLeadByte(byte value)
+        => value is >= 0x81 and <= 0x9f or >= 0xe0 and <= 0xfc;
+
+    private static bool IsTrailByte(byte value)
+        => value is >= 0x40 and <= 0x7e or >= 0x80 and <= 0xfc;
+
+    private static byte[] EncodeCString(string value, Encoding encoding)
+    {
+        int nul = value.IndexOf('\0');
+        return encoding.GetBytes(nul < 0 ? value : value[..nul]);
+    }
+
+    public static int CharacterLength(string value, Encoding encoding)
+    {
+        byte[] bytes = EncodeCString(value, encoding);
+        int count = 0;
+        for (int offset = 0; offset < bytes.Length; count++)
+        {
+            if (IsLeadByte(bytes[offset]) && offset + 1 < bytes.Length
+                                          && IsTrailByte(bytes[offset + 1]))
+                offset += 2;
+            else
+                offset++;
+        }
+        return count;
+    }
+
+    public static string Substring(
+        string value, int start, int count, Encoding encoding)
+    {
+        byte[] bytes = EncodeCString(value, encoding);
+        var characters = new List<(int Offset, int Length)>();
+        for (int offset = 0; offset < bytes.Length;)
+        {
+            int length = IsLeadByte(bytes[offset]) && offset + 1 < bytes.Length
+                                                  && IsTrailByte(bytes[offset + 1])
+                ? 2
+                : 1;
+            characters.Add((offset, length));
+            offset += length;
+        }
+
+        int end = unchecked(start + count);
+        if (end < 1 || end > characters.Count) end = characters.Count;
+
+        using var selected = new MemoryStream();
+        for (int index = 0; index < characters.Count; index++)
+        {
+            if (index < start || index >= end) continue;
+            (int offset, int length) = characters[index];
+            selected.Write(bytes, offset, length);
+        }
+        return encoding.GetString(selected.ToArray());
+    }
+
+    public static FullwidthTextValidationError ValidateFullwidthName(
+        string value, Encoding encoding, int byteLimit = NativeNameByteLimit)
+    {
+        byte[] bytes = EncodeCString(value, encoding);
+        if (bytes.Length > byteLimit) return FullwidthTextValidationError.TooLong;
+
+        for (int offset = 0; offset < bytes.Length; offset += 2)
+        {
+            if (offset + 1 >= bytes.Length
+                || !IsLeadByte(bytes[offset])
+                || !IsTrailByte(bytes[offset + 1]))
+                return FullwidthTextValidationError.NonDoubleByteCharacter;
+        }
+        return FullwidthTextValidationError.None;
+    }
+
+    public static FullwidthTextValidationError ValidateFullwidthName(
+        string value, int byteLimit = NativeNameByteLimit)
+        => ValidateFullwidthName(value, NativeEncoding, byteLimit);
+}

engine/Age.Engine/Vm/VirtualMachine.cs

@@ -2,6 +2,7 @@ using Age.Engine.Diagnostics;
 using Age.Engine.Hosting;
 using Age.Engine.Model;
 using Age.Engine.Persistence;
+using Age.Engine.Sys4;
 using System.Text;
 namespace Age.Engine.Vm;
 
@@ -1237,6 +1238,25 @@ public sealed class VirtualMachine
             case "halve-strlen": // 0x1a6: strlen(native encoded bytes) >> 1
                 Write(a[0], NativeStringByteLength(ReadStr(a[1])) >> 1);
                 return pc + 1;
+            case "edit-fullwidth-string-dialog": // 0x144: blocking AGERc command-10 editor
+            {
+                string current = ReadStr(a[0]);
+                string initial = ReadStr(a[1]);
+                FullwidthTextEditResult result =
+                    _host.EditFullwidthString(new(current, initial));
+                if (result.Accepted) WriteStr(a[0], result.Text);
+                return pc + 1;
+            }
+            case "cp932-character-length": // 0x2c6: Japanese-locale _mbstrlen
+                Write(a[0], Cp932Text.CharacterLength(ReadStr(a[1]), _nativeStringEncoding));
+                return pc + 1;
+            case "cp932-substring": // 0x2c8: multibyte-character interval [start,start+count)
+                WriteStr(a[0], Cp932Text.Substring(
+                    ReadStr(a[1]),
+                    unchecked((int)Read(a[2])),
+                    unchecked((int)Read(a[3])),
+                    _nativeStringEncoding));
+                return pc + 1;
             case "u00425790": // upstream ABI label
             case "append-diagnostic-value": // 0x1b2: generic operand text -> EngineCtx accumulator
                 _diagnosticOutput.Append(FormatDiagnosticOperand(a[0]));