inlining microoptimizations

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

@@ -5,6 +5,7 @@
 
 namespace ImageSharp.Formats.Jpg
 {
+    using System;
     using System.Runtime.CompilerServices;
 
     /// <summary>
@@ -53,39 +54,60 @@ namespace ImageSharp.Formats.Jpg
         /// <param name="n">The number of bits to ensure.</param>
         /// <param name="decoder">Jpeg decoder</param>
         /// <returns>Error code</returns>
-        [MethodImpl(MethodImplOptions.AggressiveInlining)]
+        //[MethodImpl(MethodImplOptions.AggressiveInlining)]
         public DecoderErrorCode EnsureNBitsUnsafe(int n, JpegDecoderCore decoder)
         {
             while (true)
             {
-                // Grab the decode bytes, use them and then set them
-                // back on the decoder.
-                Bytes decoderBytes = decoder.Bytes;
-                byte c;
-                DecoderErrorCode errorCode = decoderBytes.ReadByteStuffedByteUnsafe(decoder.InputStream, out c);
-                decoder.Bytes = decoderBytes;
-
-                if (errorCode != DecoderErrorCode.NoError)
+                DecoderErrorCode errorCode = this.EnsureBitsStepImpl(decoder);
+                if (errorCode != DecoderErrorCode.NoError || this.UnreadBits >= n)
                 {
                     return errorCode;
                 }
+            }
+        }
 
-                this.Accumulator = (this.Accumulator << 8) | c;
-                this.UnreadBits += 8;
-                if (this.Mask == 0)
-                {
-                    this.Mask = 1 << 7;
-                }
-                else
-                {
-                    this.Mask <<= 8;
-                }
+        /// <summary>
+        /// Unrolled version of <see cref="EnsureNBitsUnsafe"/> for n==8
+        /// </summary>
+        /// <param name="decoder"></param>
+        /// <returns></returns>
+        public DecoderErrorCode Ensure8BitsUnsafe(JpegDecoderCore decoder)
+        {
+            return this.EnsureBitsStepImpl(decoder);
+        }
 
-                if (this.UnreadBits >= n)
-                {
-                    return DecoderErrorCode.NoError;
-                }
+        /// <summary>
+        /// Unrolled version of <see cref="EnsureNBitsUnsafe"/> for n==1
+        /// </summary>
+        /// <param name="decoder"></param>
+        /// <returns></returns>
+        public DecoderErrorCode Ensure1BitUnsafe(JpegDecoderCore decoder)
+        {
+            return this.EnsureBitsStepImpl(decoder);
+        }
+
+        private DecoderErrorCode EnsureBitsStepImpl(JpegDecoderCore decoder)
+        {
+            byte c;
+            DecoderErrorCode errorCode = decoder.Bytes.ReadByteStuffedByteUnsafe(decoder.InputStream, out c);
+
+            if (errorCode != DecoderErrorCode.NoError)
+            {
+                return errorCode;
+            }
+
+            this.Accumulator = (this.Accumulator << 8) | c;
+            this.UnreadBits += 8;
+            if (this.Mask == 0)
+            {
+                this.Mask = 1 << 7;
+            }
+            else
+            {
+                this.Mask <<= 8;
             }
+            return errorCode;
         }
 
         /// <summary>

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

@@ -144,7 +144,7 @@ namespace ImageSharp.Formats.Jpg
         /// <param name="inputStream">Input stream</param>
         /// <param name="result">The result <see cref="byte"/> as out parameter</param>
         /// <returns>The <see cref="DecoderErrorCode"/></returns>
-        [MethodImpl(MethodImplOptions.AggressiveInlining)]
+        //[MethodImpl(MethodImplOptions.AggressiveInlining)]
         public DecoderErrorCode ReadByteUnsafe(Stream inputStream, out byte result)
         {
             DecoderErrorCode errorCode = DecoderErrorCode.NoError;
@@ -184,7 +184,7 @@ namespace ImageSharp.Formats.Jpg
         /// </summary>
         /// <param name="inputStream">Input stream</param>
         /// <returns>The <see cref="DecoderErrorCode"/></returns>
-        [MethodImpl(MethodImplOptions.AggressiveInlining)]
+        //[MethodImpl(MethodImplOptions.AggressiveInlining)]
         public DecoderErrorCode FillUnsafe(Stream inputStream)
         {
             if (this.I != this.J)

src/ImageSharp.Formats.Jpeg/JpegDecoderCore.cs

@@ -229,7 +229,8 @@ namespace ImageSharp.Formats
         {
             if (this.Bits.UnreadBits == 0)
             {
-                DecoderErrorCode errorCode = this.Bits.EnsureNBitsUnsafe(1, this);
+                //DecoderErrorCode errorCode = this.Bits.EnsureNBitsUnsafe(1, this);
+                DecoderErrorCode errorCode = this.Bits.Ensure1BitUnsafe(this);
                 if (errorCode != DecoderErrorCode.NoError)
                 {
                     result = false;
@@ -338,7 +339,8 @@ namespace ImageSharp.Formats
 
             if (this.Bits.UnreadBits < 8)
             {
-                DecoderErrorCode errorCode = this.Bits.EnsureNBitsUnsafe(8, this);
+                //DecoderErrorCode errorCode = this.Bits.EnsureNBitsUnsafe(8, this);
+                DecoderErrorCode errorCode = this.Bits.Ensure8BitsUnsafe(this);
 
                 if (errorCode == DecoderErrorCode.NoError)
                 {

src/ImageSharp.Formats.Jpeg/project.json

@@ -42,10 +42,10 @@
       "target": "project",
       "version": "1.0.0-*"
     },
-    "StyleCop.Analyzers": {
-      "version": "1.1.0-beta001",
-      "type": "build"
-    },
+    //"StyleCop.Analyzers": {
+    //  "version": "1.1.0-beta001",
+    //  "type": "build"
+    //},
     "System.Buffers": "4.0.0",
     "System.Runtime.CompilerServices.Unsafe": "4.0.0"
   },

tests/ImageSharp.Tests/Formats/Jpg/JpegDecoderTests.cs

@@ -40,31 +40,5 @@ namespace ImageSharp.Tests
 
             provider.Utility.SaveTestOutputFile(image, "bmp");
         }
-
-        unsafe struct Buzisag
-        {
-            public int Value;
-
-            public delegate void BlockAction(Buzisag* b);
-
-            public static void Foo(Buzisag* buzisag)
-            {
-                Bar(buzisag, b => b->Value++);
-            }
-
-            public static void Bar(Buzisag* buzisag, BlockAction action)
-            {
-                action(buzisag);
-            }
-        }
-
-        [Fact]
-        public unsafe void Kabbe()
-        {
-            Buzisag b = default(Buzisag);
-            Buzisag.Foo(&b);
-
-            Assert.Equal(1, b.Value);
-        }
     }
 }