Apply suggestions from code review

Co-authored-by: Günther Foidl <gue@korporal.at>

src/ImageSharp/Formats/Tiff/Compression/Decompressors/ModifiedHuffmanBitReader.cs

@@ -26,7 +26,7 @@ namespace SixLabors.ImageSharp.Formats.Tiff.Compression.Decompressors
         }
 
         /// <inheritdoc/>
-        public override bool HasMoreData => this.Position < (ulong)this.DataLength - 1 || (this.BitsRead > 0 && this.BitsRead < 7);
+        public override bool HasMoreData => this.Position < (ulong)this.DataLength - 1 || ((uint)(this.BitsRead - 1) < (7 - 1));
 
         /// <inheritdoc/>
         public override bool IsEndOfScanLine
@@ -53,8 +53,8 @@ namespace SixLabors.ImageSharp.Formats.Tiff.Compression.Decompressors
         {
             base.StartNewRow();
 
-            int pad = 8 - (this.BitsRead % 8);
-            if (pad != 8)
+            int remainder = this.BitsRead & 7;    // bit-hack for % 8
+            if (remainder != 0)
             {
                 // Skip padding bits, move to next byte.
                 this.Position++;

src/ImageSharp/Formats/Tiff/Compression/Decompressors/T6BitReader.cs

@@ -63,7 +63,7 @@ namespace SixLabors.ImageSharp.Formats.Tiff.Compression.Decompressors
         }
 
         /// <inheritdoc/>
-        public override bool HasMoreData => this.Position < (ulong)this.DataLength - 1 || (this.BitsRead > 0 && this.BitsRead < 7);
+        public override bool HasMoreData => this.Position < (ulong)this.DataLength - 1 || ((uint)(this.BitsRead - 1) < (7 - 1));
 
         /// <summary>
         /// Gets or sets the two dimensional code.

src/ImageSharp/Formats/Tiff/Compression/Decompressors/T6TiffCompression.cs

@@ -84,8 +84,8 @@ namespace SixLabors.ImageSharp.Formats.Tiff.Compression.Decompressors
             }
 
             // Write padding bytes, if necessary.
-            uint pad = 8 - (bitsWritten % 8);
-            if (pad != 8)
+            uint remainder = bitsWritten % 8;
+            if (remainder != 0)
             {
                 BitWriterUtils.WriteBits(buffer, (int)bitsWritten, pad, 0);
                 bitsWritten += pad;