Rename and refactor method

src/ImageSharp/Common/Helpers/SimdUtils.cs

@@ -38,7 +38,7 @@ internal static partial class SimdUtils
     /// </summary>
     /// <param name="v">The vector</param>
     [MethodImpl(MethodImplOptions.AggressiveInlining)]
-    internal static Vector<float> FastRound(this Vector<float> v)
+    internal static Vector<float> RoundToNearestInteger(this Vector<float> v)
     {
         if (Avx512F.IsSupported && Vector<float>.Count == Vector512<float>.Count)
         {
@@ -59,13 +59,11 @@ internal static partial class SimdUtils
         }
 
         // https://github.com/g-truc/glm/blob/master/glm/simd/common.h#L11
-        Vector<int> magic0 = new(int.MinValue); // 0x80000000
+        Vector<float> sign = v & new Vector<float>(-0F);
-        Vector<float> sgn0 = Vector.AsVectorSingle(magic0);
+        Vector<float> val_2p23_f32 = sign | new Vector<float>(8388608F);
-        Vector<float> and0 = Vector.BitwiseAnd(sgn0, v);
-        Vector<float> or0 = Vector.BitwiseOr(and0, new Vector<float>(8388608.0f));
-        Vector<float> add0 = Vector.Add(v, or0);
 
-        return Vector.Subtract(add0, or0);
+        val_2p23_f32 = (v + val_2p23_f32) - val_2p23_f32;
+        return val_2p23_f32 | sign;
     }
 
     [Conditional("DEBUG")]

src/ImageSharp/Formats/Jpeg/Components/Block8x8F.cs

@@ -588,6 +588,6 @@ internal partial struct Block8x8F : IEquatable<Block8x8F>
         row += off;
         row = Vector.Max(row, Vector<float>.Zero);
         row = Vector.Min(row, max);
-        return row.FastRound();
+        return row.RoundToNearestInteger();
     }
 }

src/ImageSharp/Formats/Jpeg/Components/ColorConverters/JpegColorConverter.YCbCrVector.cs

@@ -55,9 +55,9 @@ internal abstract partial class JpegColorConverterBase
                 Vector<float> g = y + (cb * gCbMult) + (cr * gCrMult);
                 Vector<float> b = y + (cb * bCbMult);
 
-                r = r.FastRound();
+                r = r.RoundToNearestInteger();
-                g = g.FastRound();
+                g = g.RoundToNearestInteger();
-                b = b.FastRound();
+                b = b.RoundToNearestInteger();
                 r *= scale;
                 g *= scale;
                 b *= scale;

src/ImageSharp/Formats/Jpeg/Components/ColorConverters/JpegColorConverter.YccKVector.cs

@@ -59,9 +59,9 @@ internal abstract partial class JpegColorConverterBase
                 Vector<float> g = y + (cb * gCbMult) + (cr * gCrMult);
                 Vector<float> b = y + (cb * bCbMult);
 
-                r = (max - r.FastRound()) * scaledK;
+                r = (max - r.RoundToNearestInteger()) * scaledK;
-                g = (max - g.FastRound()) * scaledK;
+                g = (max - g.RoundToNearestInteger()) * scaledK;
-                b = (max - b.FastRound()) * scaledK;
+                b = (max - b.RoundToNearestInteger()) * scaledK;
 
                 c0 = r;
                 c1 = g;

tests/ImageSharp.Benchmarks/Codecs/Jpeg/BlockOperations/Block8x8F_Round.cs

@@ -67,21 +67,21 @@ public unsafe class Block8x8F_Round
         ref Block8x8F b = ref this.block;
 
         ref Vector<float> row0 = ref Unsafe.As<Vector4, Vector<float>>(ref b.V0L);
-        row0 = row0.FastRound();
+        row0 = row0.RoundToNearestInteger();
         ref Vector<float> row1 = ref Unsafe.As<Vector4, Vector<float>>(ref b.V1L);
-        row1 = row1.FastRound();
+        row1 = row1.RoundToNearestInteger();
         ref Vector<float> row2 = ref Unsafe.As<Vector4, Vector<float>>(ref b.V2L);
-        row2 = row2.FastRound();
+        row2 = row2.RoundToNearestInteger();
         ref Vector<float> row3 = ref Unsafe.As<Vector4, Vector<float>>(ref b.V3L);
-        row3 = row3.FastRound();
+        row3 = row3.RoundToNearestInteger();
         ref Vector<float> row4 = ref Unsafe.As<Vector4, Vector<float>>(ref b.V4L);
-        row4 = row4.FastRound();
+        row4 = row4.RoundToNearestInteger();
         ref Vector<float> row5 = ref Unsafe.As<Vector4, Vector<float>>(ref b.V5L);
-        row5 = row5.FastRound();
+        row5 = row5.RoundToNearestInteger();
         ref Vector<float> row6 = ref Unsafe.As<Vector4, Vector<float>>(ref b.V6L);
-        row6 = row6.FastRound();
+        row6 = row6.RoundToNearestInteger();
         ref Vector<float> row7 = ref Unsafe.As<Vector4, Vector<float>>(ref b.V7L);
-        row7 = row7.FastRound();
+        row7 = row7.RoundToNearestInteger();
     }
 
     [Benchmark]
@@ -90,21 +90,21 @@ public unsafe class Block8x8F_Round
         ref Block8x8F b = ref Unsafe.AsRef<Block8x8F>(this.alignedPtr);
 
         ref Vector<float> row0 = ref Unsafe.As<Vector4, Vector<float>>(ref b.V0L);
-        row0 = row0.FastRound();
+        row0 = row0.RoundToNearestInteger();
         ref Vector<float> row1 = ref Unsafe.As<Vector4, Vector<float>>(ref b.V1L);
-        row1 = row1.FastRound();
+        row1 = row1.RoundToNearestInteger();
         ref Vector<float> row2 = ref Unsafe.As<Vector4, Vector<float>>(ref b.V2L);
-        row2 = row2.FastRound();
+        row2 = row2.RoundToNearestInteger();
         ref Vector<float> row3 = ref Unsafe.As<Vector4, Vector<float>>(ref b.V3L);
-        row3 = row3.FastRound();
+        row3 = row3.RoundToNearestInteger();
         ref Vector<float> row4 = ref Unsafe.As<Vector4, Vector<float>>(ref b.V4L);
-        row4 = row4.FastRound();
+        row4 = row4.RoundToNearestInteger();
         ref Vector<float> row5 = ref Unsafe.As<Vector4, Vector<float>>(ref b.V5L);
-        row5 = row5.FastRound();
+        row5 = row5.RoundToNearestInteger();
         ref Vector<float> row6 = ref Unsafe.As<Vector4, Vector<float>>(ref b.V6L);
-        row6 = row6.FastRound();
+        row6 = row6.RoundToNearestInteger();
         ref Vector<float> row7 = ref Unsafe.As<Vector4, Vector<float>>(ref b.V7L);
-        row7 = row7.FastRound();
+        row7 = row7.RoundToNearestInteger();
     }
 
     [Benchmark]
@@ -117,20 +117,20 @@ public unsafe class Block8x8F_Round
         ref Vector<float> row2 = ref Unsafe.As<Vector4, Vector<float>>(ref b.V2L);
         ref Vector<float> row3 = ref Unsafe.As<Vector4, Vector<float>>(ref b.V3L);
 
-        row0 = row0.FastRound();
+        row0 = row0.RoundToNearestInteger();
-        row1 = row1.FastRound();
+        row1 = row1.RoundToNearestInteger();
-        row2 = row2.FastRound();
+        row2 = row2.RoundToNearestInteger();
-        row3 = row3.FastRound();
+        row3 = row3.RoundToNearestInteger();
 
         row0 = ref Unsafe.As<Vector4, Vector<float>>(ref b.V4L);
         row1 = ref Unsafe.As<Vector4, Vector<float>>(ref b.V5L);
         row2 = ref Unsafe.As<Vector4, Vector<float>>(ref b.V6L);
         row3 = ref Unsafe.As<Vector4, Vector<float>>(ref b.V7L);
 
-        row0 = row0.FastRound();
+        row0 = row0.RoundToNearestInteger();
-        row1 = row1.FastRound();
+        row1 = row1.RoundToNearestInteger();
-        row2 = row2.FastRound();
+        row2 = row2.RoundToNearestInteger();
-        row3 = row3.FastRound();
+        row3 = row3.RoundToNearestInteger();
     }
 
     [Benchmark]

tests/ImageSharp.Tests/Common/SimdUtilsTests.cs

@@ -73,7 +73,7 @@ public partial class SimdUtilsTests
     public void FastRound()
     {
         Vector<float> v = CreateExactTestVector1();
-        Vector<float> r = v.FastRound();
+        Vector<float> r = v.RoundToNearestInteger();
 
         this.Output.WriteLine(r.ToString());
 
@@ -90,7 +90,7 @@ public partial class SimdUtilsTests
     public void FastRound_RandomValues(int seed, float scale)
     {
         Vector<float> v = CreateRandomTestVector(seed, -scale * 0.5f, scale * 0.5f);
-        Vector<float> r = v.FastRound();
+        Vector<float> r = v.RoundToNearestInteger();
 
         this.Output.WriteLine(v.ToString());
         this.Output.WriteLine(r.ToString());