Strength test criteria

src/ImageSharp/Formats/Heif/Av1/Av1BitStreamReader.cs

@@ -7,7 +7,7 @@ namespace SixLabors.ImageSharp.Formats.Heif.Av1;
 
 internal ref struct Av1BitStreamReader
 {
-    private const int WordSize = 1 << WordSizeLog2;
+    public const int WordSize = 1 << WordSizeLog2;
     private const int WordSizeLog2 = 5;
     private const int WordSizeInBytesLog2 = WordSizeLog2 - Log2Of8;
     private const int Log2Of8 = 3;
@@ -182,7 +182,7 @@ internal ref struct Av1BitStreamReader
         // TODO: Pass exact byte iso Word start.
         int spanLength = tileDataSize >> WordSizeInBytesLog2;
         Span<uint> span = this.data.Slice(this.bitOffset >> WordSizeLog2, spanLength);
-        this.bitOffset += tileDataSize << Log2Of8;
+        this.Skip(tileDataSize << Log2Of8);
         return MemoryMarshal.Cast<uint, byte>(span);
     }
 }

src/ImageSharp/Formats/Heif/Av1/Av1BlockSizeExtensions.cs

@@ -68,13 +68,13 @@ internal static class Av1BlockSizeExtensions
     /// Returns base 2 logarithm of the width of the block in units of 4 samples.
     /// </summary>
     public static int Get4x4WidthLog2(this Av1BlockSize blockSize)
-        => Get4x4WideCount(blockSize) << 2;
+        => Av1Math.Log2(Get4x4WideCount(blockSize));
 
     /// <summary>
     /// Returns base 2 logarithm of the height of the block in units of 4 samples.
     /// </summary>
     public static int Get4x4HeightLog2(this Av1BlockSize blockSize)
-        => Get4x4HighCount(blockSize) << 2;
+        => Av1Math.Log2(Get4x4HighCount(blockSize));
 
     /// <summary>
     /// Returns the block size of a sub sampled block.

tests/ImageSharp.Tests/Formats/Heif/Av1/ObuFrameHeaderTests.cs

@@ -32,31 +32,36 @@ public class ObuFrameHeaderTests
         Assert.NotNull(obuReader.SequenceHeader);
         Assert.NotNull(obuReader.FrameHeader);
         Assert.NotNull(obuReader.FrameHeader.TilesInfo);
+        Assert.Equal(reader.Length * Av1BitStreamReader.WordSize, reader.BitPosition);
+        Assert.Equal(reader.Length * 4, blockSize);
     }
 
-    /* [Theory]
-    // [InlineData(TestImages.Heif.XnConvert, 0x010E, 0x03CC)]
-    // public void BinaryIdenticalRoundTripFrameHeader(string filename, int fileOffset, int blockSize)
-    // {
-    //    // Assign
-    //    string filePath = Path.Combine(TestEnvironment.InputImagesDirectoryFullPath, filename);
-    //    byte[] content = File.ReadAllBytes(filePath);
-    //    Span<byte> span = content.AsSpan(fileOffset, blockSize);
-    //    IAv1TileDecoder tileDecoder = new Av1TileDecoderStub();
-    //    Av1BitStreamReader reader = new(span);
-
-    //    // Act 1
-    //    ObuReader.Read(ref reader, blockSize, tileDecoder);
-
-    //    // Assign 2
-    //    MemoryStream encoded = new();
-
-    //    // Act 2
-    //    ObuWriter.Write(encoded, tileDecoder);
-
-    //    // Assert
-    //    Assert.Equal(span, encoded.ToArray());
-    //}
+    /*
+    [Theory]
+    [InlineData(TestImages.Heif.XnConvert, 0x010E, 0x03CC)]
+    public void BinaryIdenticalRoundTripFrameHeader(string filename, int fileOffset, int blockSize)
+    {
+        // Assign
+        string filePath = Path.Combine(TestEnvironment.InputImagesDirectoryFullPath, filename);
+        byte[] content = File.ReadAllBytes(filePath);
+        Span<byte> span = content.AsSpan(fileOffset, blockSize);
+        Av1TileDecoderStub tileDecoder = new();
+        Av1BitStreamReader reader = new(span);
+        ObuReader obuReader = new();
+
+        // Act 1
+        obuReader.Read(ref reader, blockSize, tileDecoder);
+
+        // Assign 2
+        MemoryStream encoded = new();
+
+        // Act 2
+        ObuWriter obuWriter = new();
+        ObuWriter.Write(encoded, obuReader.SequenceHeader, obuReader.FrameHeader);
+
+        // Assert
+        Assert.Equal(span, encoded.ToArray());
+    }
     */
 
     [Theory]