Use Numerics.Modulo8

src/ImageSharp/Formats/Tiff/Compression/BitWriterUtils.cs

@@ -9,12 +9,12 @@ namespace SixLabors.ImageSharp.Formats.Tiff.Compression
 {
     internal static class BitWriterUtils
     {
-        public static void WriteBits(Span<byte> buffer, int pos, uint count, byte value)
+        public static void WriteBits(Span<byte> buffer, int pos, int count, byte value)
         {
-            int bitPos = pos % 8;
+            int bitPos = Numerics.Modulo8(pos);
             int bufferPos = pos / 8;
             int startIdx = bufferPos + bitPos;
-            int endIdx = (int)(startIdx + count);
+            int endIdx = startIdx + count;
 
             if (value == 1)
             {

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

@@ -45,7 +45,7 @@ namespace SixLabors.ImageSharp.Formats.Tiff.Compression.Decompressors
             using var bitReader = new ModifiedHuffmanBitReader(stream, this.FillOrder, byteCount, this.Allocator);
 
             buffer.Clear();
-            uint bitsWritten = 0;
+            int bitsWritten = 0;
             uint pixelsWritten = 0;
             while (bitReader.HasMoreData)
             {
@@ -55,14 +55,14 @@ namespace SixLabors.ImageSharp.Formats.Tiff.Compression.Decompressors
                 {
                     if (bitReader.IsWhiteRun)
                     {
-                        BitWriterUtils.WriteBits(buffer, (int)bitsWritten, bitReader.RunLength, this.whiteValue);
+                        BitWriterUtils.WriteBits(buffer, bitsWritten, (int)bitReader.RunLength, this.whiteValue);
                     }
                     else
                     {
-                        BitWriterUtils.WriteBits(buffer, (int)bitsWritten, bitReader.RunLength, this.blackValue);
+                        BitWriterUtils.WriteBits(buffer, bitsWritten, (int)bitReader.RunLength, this.blackValue);
                     }
 
-                    bitsWritten += bitReader.RunLength;
+                    bitsWritten += (int)bitReader.RunLength;
                     pixelsWritten += bitReader.RunLength;
                 }
 
@@ -72,10 +72,10 @@ namespace SixLabors.ImageSharp.Formats.Tiff.Compression.Decompressors
                     pixelsWritten = 0;
 
                     // Write padding bits, if necessary.
-                    uint pad = 8 - (bitsWritten % 8);
+                    int pad = 8 - Numerics.Modulo8(bitsWritten);
                     if (pad != 8)
                     {
-                        BitWriterUtils.WriteBits(buffer, (int)bitsWritten, pad, 0);
+                        BitWriterUtils.WriteBits(buffer, bitsWritten, pad, 0);
                         bitsWritten += pad;
                     }
                 }

src/ImageSharp/Formats/Tiff/Compression/Decompressors/T4TiffCompression.cs

@@ -84,7 +84,7 @@ namespace SixLabors.ImageSharp.Formats.Tiff.Compression.Decompressors
                     uint pad = 8 - (bitsWritten % 8);
                     if (pad != 8)
                     {
-                        BitWriterUtils.WriteBits(buffer, (int)bitsWritten, pad, 0);
+                        BitWriterUtils.WriteBits(buffer, (int)bitsWritten, (int)pad, 0);
                         bitsWritten += pad;
                     }
 
@@ -104,11 +104,11 @@ namespace SixLabors.ImageSharp.Formats.Tiff.Compression.Decompressors
         {
             if (bitReader.IsWhiteRun)
             {
-                BitWriterUtils.WriteBits(buffer, (int)bitsWritten, bitReader.RunLength, this.whiteValue);
+                BitWriterUtils.WriteBits(buffer, (int)bitsWritten, (int)bitReader.RunLength, this.whiteValue);
             }
             else
             {
-                BitWriterUtils.WriteBits(buffer, (int)bitsWritten, bitReader.RunLength, this.blackValue);
+                BitWriterUtils.WriteBits(buffer, (int)bitsWritten, (int)bitReader.RunLength, this.blackValue);
             }
         }
 

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

@@ -60,7 +60,7 @@ namespace SixLabors.ImageSharp.Formats.Tiff.Compression.Decompressors
             using var bitReader = new T6BitReader(stream, this.FillOrder, byteCount, this.Allocator);
 
             var referenceScanLine = new CcittReferenceScanline(this.isWhiteZero, this.width);
-            uint bitsWritten = 0;
+            int bitsWritten = 0;
             for (int y = 0; y < height; y++)
             {
                 scanLine.Clear();
@@ -73,10 +73,10 @@ namespace SixLabors.ImageSharp.Formats.Tiff.Compression.Decompressors
             }
         }
 
-        private uint WriteScanLine(Span<byte> buffer, Span<byte> scanLine, uint bitsWritten)
+        private int WriteScanLine(Span<byte> buffer, Span<byte> scanLine, int bitsWritten)
         {
-            int bitPos = (int)(bitsWritten % 8);
+            int bitPos = Numerics.Modulo8(bitsWritten);
-            int bufferPos = (int)(bitsWritten / 8);
+            int bufferPos = bitsWritten / 8;
             for (nint i = 0; i < scanLine.Length; i++)
             {
                 if (Unsafe.Add(ref MemoryMarshal.GetReference(scanLine), i) != this.white)
@@ -95,11 +95,11 @@ namespace SixLabors.ImageSharp.Formats.Tiff.Compression.Decompressors
             }
 
             // Write padding bytes, if necessary.
-            uint remainder = bitsWritten % 8;
+            int remainder = bitsWritten % 8;
             if (remainder != 0)
             {
-                uint padding = 8 - remainder;
+                int padding = 8 - remainder;
-                BitWriterUtils.WriteBits(buffer, (int)bitsWritten, padding, 0);
+                BitWriterUtils.WriteBits(buffer, bitsWritten, padding, 0);
                 bitsWritten += padding;
             }