Support Kamek v2 Code.pul files (#126)

translator/src/Translator.Core/Parsing/Kamek/KamekChunk.cs

@@ -6,6 +6,12 @@ namespace Translator.Core.Parsing.Kamek;
 public sealed class KamekChunk
 {
     public const uint Magic0 = 0x4B616D65;
+    /// <summary>
+    /// Kamek v2 is still emitted by current Retro Rewind releases. Its command
+    /// stream matches v3, but combined v2 files carry each chunk length only in
+    /// the outer size table.
+    /// </summary>
+    public const uint Magic1V2 = 0x6B000002;
     public const uint Magic1 = 0x6B000003;
     public const int HeaderSize = 0x20;
 
@@ -58,7 +64,7 @@ public sealed class KamekChunk
         }
 
         return BinaryPrimitives.ReadUInt32BigEndian(data.Slice(offset, 4)) == Magic0 &&
-            BinaryPrimitives.ReadUInt32BigEndian(data.Slice(offset + 4, 4)) == Magic1;
+            IsSupportedFormatVersion(BinaryPrimitives.ReadUInt32BigEndian(data.Slice(offset + 4, 4)));
     }
 
     public static KamekChunk Parse(byte[] data, int offset, int expectedSize, int index)
@@ -74,7 +80,7 @@ public sealed class KamekChunk
 
         var magic0 = reader.ReadUInt32();
         var magic1 = reader.ReadUInt32();
-        if (magic0 != Magic0 || magic1 != Magic1)
+        if (magic0 != Magic0 || !IsSupportedFormatVersion(magic1))
         {
             throw new InvalidDataException($"Kamek chunk {index} at 0x{offset:X} has invalid magic 0x{magic0:X8}/0x{magic1:X8}.");
         }
@@ -83,9 +89,15 @@ public sealed class KamekChunk
         var codeSize = reader.ReadUInt32();
         var ctorStart = reader.ReadUInt32();
         var ctorEnd = reader.ReadUInt32();
-        var chunkSize = reader.ReadUInt32();
+        var declaredChunkSize = reader.ReadUInt32();
         _ = reader.ReadUInt32(); // reserved
 
+        // v3 writes each chunk's length in its header. v2 leaves that field at
+        // zero and relies on the combined-file table (or the raw file length).
+        var chunkSize = magic1 == Magic1V2
+            ? checked((uint)(expectedSize != 0 ? expectedSize : data.Length - offset))
+            : declaredChunkSize;
+
         if (chunkSize < HeaderSize + codeSize)
         {
             throw new InvalidDataException($"Kamek chunk {index} chunkSize 0x{chunkSize:X} is smaller than header+code.");
@@ -171,4 +183,7 @@ public sealed class KamekChunk
         KamekCommandId.BranchLink => 1,
         _ => throw new ArgumentOutOfRangeException(nameof(id), id, "Unsupported Kamek command id")
     };
+
+    private static bool IsSupportedFormatVersion(uint magic1) =>
+        magic1 is Magic1V2 or Magic1;
 }

translator/src/Translator.Core/Parsing/Kamek/KamekPulFile.cs

@@ -33,7 +33,7 @@ public sealed class KamekPulFile
 
         if (!KamekChunk.HasMagic(data, 0))
         {
-            throw new InvalidDataException("File is neither a combined Code.pul nor a raw Kamek v3 chunk.");
+            throw new InvalidDataException("File is neither a combined Code.pul nor a raw supported Kamek chunk.");
         }
 
         var rawChunk = KamekChunk.Parse(data, 0, expectedSize: 0, index: 0);

translator/tests/Translator.Tests/KamekPulFileTests.cs

@@ -49,6 +49,27 @@ public class KamekPulFileTests
         Assert.Equal(0x20u, pul.SelectRegion("E").BssSize);
     }
 
+    [Fact]
+    public void ParsesKamekV2CombinedChunks()
+    {
+        var p = BuildChunk(0x10, [0x4E, 0x80, 0x00, 0x20],
+            [BuildCommand(KamekCommandId.Branch, true, 0x8053369C, [0x100])], KamekChunk.Magic1V2);
+        var combined = new byte[0x10 + p.Length];
+        WriteU32(combined, 0, (uint)p.Length);
+        p.CopyTo(combined, 0x10);
+
+        var pul = KamekPulFile.Parse(combined);
+
+        Assert.True(pul.IsCombined);
+        Assert.Equal(0x10u, pul.SelectRegion("P").BssSize);
+        Assert.Equal(KamekCommandId.Branch, pul.SelectRegion("P").Commands.Single().Id);
+
+        var raw = KamekPulFile.Parse(p);
+
+        Assert.False(raw.IsCombined);
+        Assert.Equal((uint)p.Length, raw.Chunks.Single().ChunkSize);
+    }
+
     [Fact]
     public void EncodesPpcBranchLikeKamek()
     {
@@ -83,18 +104,19 @@ public class KamekPulFileTests
         Assert.Equal(chunk.Commands.Count, chunk.CommandCounts.Values.Sum());
     }
 
-    private static byte[] BuildChunk(uint bssSize, byte[] code, byte[][] commands)
+    private static byte[] BuildChunk(uint bssSize, byte[] code, byte[][] commands,
+        uint magic1 = KamekChunk.Magic1)
     {
         var commandSize = commands.Sum(c => c.Length);
         var chunkSize = KamekChunk.HeaderSize + code.Length + commandSize;
         var data = new byte[chunkSize];
         WriteU32(data, 0x00, KamekChunk.Magic0);
-        WriteU32(data, 0x04, KamekChunk.Magic1);
+        WriteU32(data, 0x04, magic1);
         WriteU32(data, 0x08, bssSize);
         WriteU32(data, 0x0C, (uint)code.Length);
         WriteU32(data, 0x10, 0);
         WriteU32(data, 0x14, 0);
-        WriteU32(data, 0x18, (uint)chunkSize);
+        WriteU32(data, 0x18, magic1 == KamekChunk.Magic1V2 ? 0u : (uint)chunkSize);
         code.CopyTo(data, KamekChunk.HeaderSize);
 
         var offset = KamekChunk.HeaderSize + code.Length;