Modernize PorterDuffFunctions with operators and add tests

src/ImageSharp/Common/Helpers/Numerics.cs

@@ -643,6 +643,20 @@ public static Vector256<float> UnPremultiply(Vector256<float> source, Vector256<
         return Avx.Blend(result, alpha, BlendAlphaControl);
     }
 
+    [MethodImpl(MethodImplOptions.AggressiveInlining)]
+    public static Vector512<float> UnPremultiply(Vector512<float> source, Vector512<float> alpha)
+    {
+        // Check if alpha is zero to avoid division by zero
+        Vector512<float> zeroMask = Vector512.Equals(alpha, Vector512<float>.Zero);
+
+        // Divide source by alpha if alpha is nonzero, otherwise set all components to match the source value
+        Vector512<float> result = Vector512.ConditionalSelect(zeroMask, source, source / alpha);
+
+        // Blend the result with the alpha vector to ensure that the alpha component is unchanged
+        Vector512<float> alphaMask = Vector512.Create(0, 0, 0, -1, 0, 0, 0, -1, 0, 0, 0, -1, 0, 0, 0, -1).AsSingle();
+        return Vector512.ConditionalSelect(alphaMask, alpha, result);
+    }
+
     /// <summary>
     /// Permutes the given vector return a new instance with all the values set to <see cref="Vector4.W"/>.
     /// </summary>
@@ -690,7 +704,7 @@ public static Vector4 WithW(Vector4 value, Vector4 w)
     /// </summary>
     /// <param name="vectors">The span of vectors</param>
     [MethodImpl(MethodImplOptions.AggressiveInlining)]
-    public static unsafe void CubePowOnXYZ(Span<Vector4> vectors)
+    public static void CubePowOnXYZ(Span<Vector4> vectors)
     {
         ref Vector4 baseRef = ref MemoryMarshal.GetReference(vectors);
         ref Vector4 endRef = ref Unsafe.Add(ref baseRef, (uint)vectors.Length);

src/ImageSharp/Common/Helpers/SimdUtils.HwIntrinsics.cs

@@ -601,51 +601,6 @@ private static void Shuffle4Slice3(
             }
         }
 
-        /// <summary>
-        /// Performs a multiplication and an addition of the <see cref="Vector256{Single}"/>.
-        /// TODO: Fix. The arguments are in a different order to the FMA intrinsic.
-        /// </summary>
-        /// <remarks>ret = (vm0 * vm1) + va</remarks>
-        /// <param name="va">The vector to add to the intermediate result.</param>
-        /// <param name="vm0">The first vector to multiply.</param>
-        /// <param name="vm1">The second vector to multiply.</param>
-        /// <returns>The <see cref="Vector256{T}"/>.</returns>
-        [MethodImpl(InliningOptions.AlwaysInline)]
-        public static Vector256<float> MultiplyAdd(
-            Vector256<float> va,
-            Vector256<float> vm0,
-            Vector256<float> vm1)
-        {
-            if (Fma.IsSupported)
-            {
-                return Fma.MultiplyAdd(vm1, vm0, va);
-            }
-
-            return va + (vm0 * vm1);
-        }
-
-        /// <summary>
-        /// Performs a multiplication and a negated addition of the <see cref="Vector256{Single}"/>.
-        /// </summary>
-        /// <remarks>ret = c - (a * b)</remarks>
-        /// <param name="a">The first vector to multiply.</param>
-        /// <param name="b">The second vector to multiply.</param>
-        /// <param name="c">The vector to add negated to the intermediate result.</param>
-        /// <returns>The <see cref="Vector256{T}"/>.</returns>
-        [MethodImpl(InliningOptions.ShortMethod)]
-        public static Vector256<float> MultiplyAddNegated(
-            Vector256<float> a,
-            Vector256<float> b,
-            Vector256<float> c)
-        {
-            if (Fma.IsSupported)
-            {
-                return Fma.MultiplyAddNegated(a, b, c);
-            }
-
-            return Avx.Subtract(c, Avx.Multiply(a, b));
-        }
-
         /// <summary>
         /// Blend packed 8-bit integers from <paramref name="left"/> and <paramref name="right"/> using <paramref name="mask"/>.
         /// The high bit of each corresponding <paramref name="mask"/> byte determines the selection.

src/ImageSharp/Common/Helpers/Vector256Utilities.cs

@@ -115,6 +115,28 @@ public static Vector256<float> MultiplyAdd(
         return va + (vm0 * vm1);
     }
 
+    /// <summary>
+    /// Performs a multiplication and a negated addition of the <see cref="Vector256{Single}"/>.
+    /// </summary>
+    /// <remarks>ret = va - (vm0 * vm1)</remarks>
+    /// <param name="va">The vector to add to the negated intermediate result.</param>
+    /// <param name="vm0">The first vector to multiply.</param>
+    /// <param name="vm1">The second vector to multiply.</param>
+    /// <returns>The <see cref="Vector256{T}"/>.</returns>
+    [MethodImpl(InliningOptions.ShortMethod)]
+    public static Vector256<float> MultiplyAddNegated(
+        Vector256<float> va,
+        Vector256<float> vm0,
+        Vector256<float> vm1)
+    {
+        if (Fma.IsSupported)
+        {
+            return Fma.MultiplyAddNegated(vm0, vm1, va);
+        }
+
+        return va - (vm0 * vm1);
+    }
+
     /// <summary>
     /// Performs a multiplication and a subtraction of the <see cref="Vector256{Single}"/>.
     /// </summary>

src/ImageSharp/Common/Helpers/Vector512Utilities.cs

@@ -87,6 +87,21 @@ public static Vector512<float> MultiplyAdd(
         Vector512<float> vm1)
         => Avx512F.FusedMultiplyAdd(vm0, vm1, va);
 
+    /// <summary>
+    /// Performs a multiplication and a negated addition of the <see cref="Vector512{Single}"/>.
+    /// </summary>
+    /// <remarks>ret = va - (vm0 * vm1)</remarks>
+    /// <param name="va">The vector to add to the negated intermediate result.</param>
+    /// <param name="vm0">The first vector to multiply.</param>
+    /// <param name="vm1">The second vector to multiply.</param>
+    /// <returns>The <see cref="Vector512{T}"/>.</returns>
+    [MethodImpl(MethodImplOptions.AggressiveInlining)]
+    public static Vector512<float> MultiplyAddNegated(
+        Vector512<float> va,
+        Vector512<float> vm0,
+        Vector512<float> vm1)
+        => Avx512F.FusedMultiplyAddNegated(vm0, vm1, va);
+
     /// <summary>
     /// Restricts a vector between a minimum and a maximum value.
     /// </summary>