Fixed Bug Pt. II

Author: gfoidl

src/ImageSharp/Formats/Jpeg/Components/Decoder/ArithmeticScanDecoder.cs

@@ -53,7 +53,7 @@ internal class ArithmeticScanDecoder : IJpegScanDecoder
 
     private ArithmeticDecodingTable[] acDecodingTables;
 
-    private static readonly byte[] FixedBin = { 113, 0, 0, 0 };
+    private readonly byte[] fixedBin = { 113, 0, 0, 0 };
 
     private readonly CancellationToken cancellationToken;
 
@@ -231,7 +231,7 @@ public void InitDecodingTables(List<ArithmeticDecodingTable> arithmeticDecodingT
         }
     }
 
-    private static ref byte GetFixedBinReference() => ref MemoryMarshal.GetArrayDataReference(FixedBin);
+    private ref byte GetFixedBinReference() => ref MemoryMarshal.GetArrayDataReference(this.fixedBin);
 
     /// <summary>
     /// Decodes the entropy coded data.
@@ -775,7 +775,7 @@ private void DecodeBlockProgressiveDc(ArithmeticDecodingComponent component, ref
         else
         {
             // Refinement scan.
-            ref byte st = ref GetFixedBinReference();
+            ref byte st = ref this.GetFixedBinReference();
 
             blockDataRef |= (short)(this.DecodeBinaryDecision(ref reader, ref st) << this.SuccessiveLow);
         }
@@ -821,7 +821,7 @@ private void DecodeBlockProgressiveAc(ArithmeticDecodingComponent component, ref
 
                 // Figure F.21: Decoding nonzero value v.
                 // Figure F.22: Decoding the sign of v.
-                int sign = this.DecodeBinaryDecision(ref reader, ref GetFixedBinReference());
+                int sign = this.DecodeBinaryDecision(ref reader, ref this.GetFixedBinReference());
                 st = ref Unsafe.Add(ref st, 2);
 
                 // Figure F.23: Decoding the magnitude category of v.
@@ -917,7 +917,7 @@ private void ReadBlockProgressiveAcRefined(ArithmeticStatistics acStatistics, re
 
                 if (this.DecodeBinaryDecision(ref reader, ref Unsafe.Add(ref st, 1)) != 0)
                 {
-                    bool flag = this.DecodeBinaryDecision(ref reader, ref GetFixedBinReference()) != 0;
+                    bool flag = this.DecodeBinaryDecision(ref reader, ref this.GetFixedBinReference()) != 0;
                     coef = (short)(coef + (flag ? m1 : p1));
 
                     break;
@@ -1047,7 +1047,7 @@ private void DecodeBlockBaseline(
 
             // Figure F.21: Decoding nonzero value v.
             // Figure F.22: Decoding the sign of v.
-            int sign = this.DecodeBinaryDecision(ref reader, ref GetFixedBinReference());
+            int sign = this.DecodeBinaryDecision(ref reader, ref this.GetFixedBinReference());
             st = ref Unsafe.Add(ref st, 2);
 
             // Figure F.23: Decoding the magnitude category of v.

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

@@ -1440,12 +1440,7 @@ private static uint ClampedAddSubtractHalf(uint c0, uint c1, uint c2)
     }
 
     [MethodImpl(InliningOptions.ShortMethod)]
-    private static int AddSubtractComponentHalf(int a, int b)
-    {
-        uint ua = (uint)a;
-        uint ub = (uint)b;
-        return (int)Clip255(ua + ((ua - ub) / 2));
-    }
+    private static int AddSubtractComponentHalf(int a, int b) => (int)Clip255((uint)(a + ((a - b) >> 1)));  // >> 1 is bit-hack for / 2
 
     [MethodImpl(InliningOptions.ShortMethod)]
     private static int AddSubtractComponentFull(int a, int b, int c) => (int)Clip255((uint)(a + b - c));