Fix for new compression type

AssetStudio/BundleFile.cs

@@ -35,7 +35,7 @@ namespace AssetStudio
         Lzma,
         Lz4,
         Lz4HC,
-        Lzham
+        Lz4Inv,
     }
 
     public class BundleFile
@@ -378,20 +378,31 @@ namespace AssetStudio
                         }
                     case CompressionType.Lz4:
                     case CompressionType.Lz4HC:
+                    case CompressionType.Lz4Inv:
                         {
                             var compressedSize = (int)blockInfo.compressedSize;
                             var compressedBytes = BigArrayPool<byte>.Shared.Rent(compressedSize);
-                            reader.Read(compressedBytes, 0, compressedSize);
+                            _ = reader.Read(compressedBytes, 0, compressedSize);
                             var uncompressedSize = (int)blockInfo.uncompressedSize;
                             var uncompressedBytes = BigArrayPool<byte>.Shared.Rent(uncompressedSize);
-                            var numWrite = LZ4Codec.Decode(compressedBytes, 0, compressedSize, uncompressedBytes, 0, uncompressedSize);
+                            try
-                            if (numWrite != uncompressedSize)
                             {
-                                throw new IOException($"Lz4 decompression error, write {numWrite} bytes but expected {uncompressedSize} bytes");
+                                var compressedSpan = compressedBytes.AsSpan(0, compressedSize);
+                                var uncompressedSpan = uncompressedBytes.AsSpan(0, uncompressedSize);
+                                var numWrite = compressionType == CompressionType.Lz4Inv
+                                    ? LZ4Inv.Instance.Decompress(compressedSpan, uncompressedSpan)
+                                    : LZ4Codec.Decode(compressedSpan, uncompressedSpan);
+                                if (numWrite != uncompressedSize)
+                                {
+                                    throw new IOException($"Lz4 decompression error, write {numWrite} bytes but expected {uncompressedSize} bytes");
+                                }
+                                blocksStream.Write(uncompressedBytes, 0, uncompressedSize);
+                            }
+                            finally
+                            {
+                                BigArrayPool<byte>.Shared.Return(compressedBytes);
+                                BigArrayPool<byte>.Shared.Return(uncompressedBytes);
                             }
-                            blocksStream.Write(uncompressedBytes, 0, uncompressedSize);
-                            BigArrayPool<byte>.Shared.Return(compressedBytes);
-                            BigArrayPool<byte>.Shared.Return(uncompressedBytes);
                             break;
                         }
                     default:

AssetStudio/LZ4/LZ4.cs

@@ -0,0 +1,75 @@
+using System;
+
+namespace AssetStudio
+{
+    public class LZ4
+    {
+        public static LZ4 Instance => new LZ4();
+
+        public virtual int Decompress(ReadOnlySpan<byte> cmp, Span<byte> dec)
+        {
+            int cmpPos = 0;
+            int decPos = 0;
+
+            do
+            {
+                var (encCount, litCount) = GetLiteralToken(cmp, ref cmpPos);
+
+                //Copy literal chunk
+                litCount = GetLength(litCount, cmp, ref cmpPos);
+
+                cmp.Slice(cmpPos, litCount).CopyTo(dec.Slice(decPos));
+
+                cmpPos += litCount;
+                decPos += litCount;
+
+                if (cmpPos >= cmp.Length)
+                {
+                    break;
+                }
+
+                //Copy compressed chunk
+                int back = GetChunkEnd(cmp, ref cmpPos);
+
+                encCount = GetLength(encCount, cmp, ref cmpPos) + 4;
+
+                int encPos = decPos - back;
+
+                if (encCount <= back)
+                {
+                    dec.Slice(encPos, encCount).CopyTo(dec.Slice(decPos));
+                    decPos += encCount;
+                }
+                else
+                {
+                    while (encCount-- > 0)
+                    {
+                        dec[decPos++] = dec[encPos++];
+                    }
+                }
+            } while (cmpPos < cmp.Length && decPos < dec.Length);
+
+            return decPos;
+        }
+
+        protected virtual (int encCount, int litCount) GetLiteralToken(ReadOnlySpan<byte> cmp, ref int cmpPos) =>
+            ((cmp[cmpPos] >> 0) & 0xf, (cmp[cmpPos++] >> 4) & 0xf);
+
+        protected virtual int GetChunkEnd(ReadOnlySpan<byte> cmp, ref int cmpPos) =>
+            cmp[cmpPos++] << 0 | cmp[cmpPos++] << 8;
+
+        protected virtual int GetLength(int length, ReadOnlySpan<byte> cmp, ref int cmpPos)
+        {
+            byte sum;
+
+            if (length == 0xf)
+            {
+                do
+                {
+                    length += sum = cmp[cmpPos++];
+                } while (sum == 0xff);
+            }
+            return length;
+        }
+    }
+}

AssetStudio/LZ4/LZ4Inv.cs

@@ -0,0 +1,15 @@
+using System;
+
+namespace AssetStudio
+{
+    public class LZ4Inv : LZ4
+    {
+        public new static LZ4Inv Instance => new LZ4Inv();
+
+        protected override (int encCount, int litCount) GetLiteralToken(ReadOnlySpan<byte> cmp, ref int cmpPos) =>
+            ((cmp[cmpPos] >> 4) & 0xf, (cmp[cmpPos++] >> 0) & 0xf);
+
+        protected override int GetChunkEnd(ReadOnlySpan<byte> cmp, ref int cmpPos) =>
+            cmp[cmpPos++] << 8 | cmp[cmpPos++] << 0;
+    }
+}