Use Numerics.Log2

src/ImageSharp/Formats/Webp/BitReader/Vp8BitReader.cs

@@ -111,7 +111,7 @@ namespace SixLabors.ImageSharp.Formats.Webp.BitReader
                 range = split + 1;
             }
 
-            int shift = 7 ^ WebpCommonUtils.BitsLog2Floor(range);
+            int shift = 7 ^ Numerics.Log2(range);
             range <<= shift;
             this.bits -= shift;
 

src/ImageSharp/Formats/Webp/Lossless/LosslessUtils.cs

@@ -847,7 +847,7 @@ namespace SixLabors.ImageSharp.Formats.Webp.Lossless
         /// </summary>
         private static int PrefixEncodeBitsNoLut(int distance, ref int extraBits)
         {
-            int highestBit = WebpCommonUtils.BitsLog2Floor((uint)--distance);
+            int highestBit = Numerics.Log2((uint)--distance);
             int secondHighestBit = (distance >> (highestBit - 1)) & 1;
             extraBits = highestBit - 1;
             int code = (2 * highestBit) + secondHighestBit;
@@ -856,7 +856,7 @@ namespace SixLabors.ImageSharp.Formats.Webp.Lossless
 
         private static int PrefixEncodeNoLut(int distance, ref int extraBits, ref int extraBitsValue)
         {
-            int highestBit = WebpCommonUtils.BitsLog2Floor((uint)--distance);
+            int highestBit = Numerics.Log2((uint)--distance);
             int secondHighestBit = (distance >> (highestBit - 1)) & 1;
             extraBits = highestBit - 1;
             extraBitsValue = distance & ((1 << extraBits) - 1);

src/ImageSharp/Formats/Webp/Lossless/Vp8LEncoder.cs

@@ -330,7 +330,7 @@ namespace SixLabors.ImageSharp.Formats.Webp.Lossless
                     // If using a color cache, do not have it bigger than the number of colors.
                     if (useCache && this.PaletteSize < 1 << WebpConstants.MaxColorCacheBits)
                     {
-                        this.CacheBits = WebpCommonUtils.BitsLog2Floor((uint)this.PaletteSize) + 1;
+                        this.CacheBits = Numerics.Log2((uint)this.PaletteSize) + 1;
                     }
                 }
 
@@ -893,7 +893,7 @@ namespace SixLabors.ImageSharp.Formats.Webp.Lossless
                 }
                 else
                 {
-                    int nBits = WebpCommonUtils.BitsLog2Floor((uint)trimmedLength - 2);
+                    int nBits = Numerics.Log2((uint)trimmedLength - 2);
                     int nBitPairs = (nBits / 2) + 1;
                     this.bitWriter.PutBits((uint)nBitPairs - 1, 3);
                     this.bitWriter.PutBits((uint)trimmedLength - 2, nBitPairs * 2);

src/ImageSharp/Formats/Webp/WebpCommonUtils.cs

@@ -2,7 +2,6 @@
 // Licensed under the Apache License, Version 2.0.
 
 using System;
-using System.Runtime.CompilerServices;
 using System.Runtime.InteropServices;
 using SixLabors.ImageSharp.PixelFormats;
 #if SUPPORTS_RUNTIME_INTRINSICS
@@ -17,22 +16,6 @@ namespace SixLabors.ImageSharp.Formats.Webp
     /// </summary>
     internal static class WebpCommonUtils
     {
-        /// <summary>
-        /// Returns 31 ^ clz(n) = log2(n).Returns 31 ^ clz(n) = log2(n).
-        /// </summary>
-        [MethodImpl(InliningOptions.ShortMethod)]
-        public static int BitsLog2Floor(uint n)
-        {
-            int logValue = 0;
-            while (n >= 256)
-            {
-                logValue += 8;
-                n >>= 8;
-            }
-
-            return logValue + Unsafe.Add(ref MemoryMarshal.GetReference(WebpLookupTables.LogTable8Bit), (int)n);
-        }
-
         /// <summary>
         /// Checks if the pixel row is not opaque.
         /// </summary>