Code fixup, fast Int8 packing

X10D.Tests/src/Collections/BoolListTests.cs

@@ -6,6 +6,13 @@ namespace X10D.Tests.Collections;
 [TestClass]
 public class BoolListTests
 {
+    [TestMethod]
+    public void Pack8BitSpan_Should_Pack_Correctly()
+    {
+        Span<bool> span = stackalloc bool[8] { true, false, true, false, true, false, true, false };
+        Assert.AreEqual(85, span.PackByte()); // 01010101
+    }
+
     [TestMethod]
     public void Pack8Bit_Should_Pack_Correctly()
     {

X10D/src/Collections/ByteExtensions.cs

@@ -22,7 +22,7 @@ public static class ByteExtensions
     [Pure]
     public static bool[] Unpack(this byte value)
     {
-        bool[] buffer = new bool[Size];
+        var buffer = new bool[Size];
         value.Unpack(buffer);
         return buffer;
     }
@@ -59,10 +59,10 @@ public static class ByteExtensions
                     0x01, 0x02, 0x04, 0x08, 0x10, 0x20, 0x40, 0x80,
                     0x01, 0x02, 0x04, 0x08, 0x10, 0x20, 0x40, 0x80
                 );
-                var mask1Lo = Vector128.Create((byte)0, 0, 0, 0, 0, 0, 0, 0, 1, 1, 1, 1, 1, 1, 1, 1);
+                var mask1 = Vector128.Create((byte)0, 0, 0, 0, 0, 0, 0, 0, 1, 1, 1, 1, 1, 1, 1, 1);
 
                 var vec = Vector128.Create(value).AsByte();
-                var shuffle = Ssse3.Shuffle(vec, mask1Lo);
+                var shuffle = Ssse3.Shuffle(vec, mask1);
                 var and = Sse2.AndNot(shuffle, mask2);
                 var cmp = Sse2.CompareEqual(and, Vector128<byte>.Zero);
                 var correctness = Sse2.And(cmp, Vector128.Create((byte)0x01));

X10D/src/Collections/DictionaryExtensions.cs

@@ -66,12 +66,12 @@ public static class DictionaryExtensions
 
         return value;
 #else
-        if (dictionary.TryGetValue(key, out var old))
+        if (dictionary.TryGetValue(key, out TValue? old))
         {
-            var newValue = updateValueFactory(key, old);
+            var updated = updateValueFactory(key, old);
-            dictionary[key] = newValue;
+            dictionary[key] = updated;
 
-            return newValue;
+            return updated;
         }
         else
         {
@@ -124,12 +124,12 @@ public static class DictionaryExtensions
         }
 #endif
 
-        if (dictionary.TryGetValue(key, out var old))
+        if (dictionary.TryGetValue(key, out TValue? old))
         {
-            var newValue = updateValueFactory(key, old);
+            var updated = updateValueFactory(key, old);
-            dictionary[key] = newValue;
+            dictionary[key] = updated;
 
-            return newValue;
+            return updated;
         }
         else
         {
@@ -192,7 +192,7 @@ public static class DictionaryExtensions
 #endif
 
 #if NET6_0_OR_GREATER
-        ref var value = ref CollectionsMarshal.GetValueRefOrAddDefault(dictionary, key, out bool exists);
+        ref TValue? value = ref CollectionsMarshal.GetValueRefOrAddDefault(dictionary, key, out bool exists);
         if (exists)
         {
             value = updateValueFactory(key, value!);
@@ -204,12 +204,12 @@ public static class DictionaryExtensions
 
         return value;
 #else
-        if (dictionary.TryGetValue(key, out var old))
+        if (dictionary.TryGetValue(key, out TValue? old))
         {
-            var update = updateValueFactory(key, old);
+            var updated = updateValueFactory(key, old);
-            dictionary[key] = update;
+            dictionary[key] = updated;
 
-            return update;
+            return updated;
         }
         else
         {
@@ -274,12 +274,12 @@ public static class DictionaryExtensions
         }
 #endif
 
-        if (dictionary.TryGetValue(key, out var old))
+        if (dictionary.TryGetValue(key, out TValue? old))
         {
-            var update = updateValueFactory(key, old);
+            var updated = updateValueFactory(key, old);
-            dictionary[key] = update;
+            dictionary[key] = updated;
 
-            return update;
+            return updated;
         }
         else
         {
@@ -350,7 +350,7 @@ public static class DictionaryExtensions
 #endif
 
 #if NET6_0_OR_GREATER
-        ref var value = ref CollectionsMarshal.GetValueRefOrAddDefault(dictionary, key, out bool exists);
+        ref TValue? value = ref CollectionsMarshal.GetValueRefOrAddDefault(dictionary, key, out bool exists);
         if (exists)
         {
             value = updateValueFactory(key, value!, factoryArgument);
@@ -362,12 +362,12 @@ public static class DictionaryExtensions
 
         return value;
 #else
-        if (dictionary.TryGetValue(key, out var old))
+        if (dictionary.TryGetValue(key, out TValue? old))
         {
-            var update = updateValueFactory(key, old, factoryArgument);
+            var updated = updateValueFactory(key, old, factoryArgument);
-            dictionary[key] = update;
+            dictionary[key] = updated;
 
-            return update;
+            return updated;
         }
         else
         {
@@ -438,12 +438,12 @@ public static class DictionaryExtensions
         }
 #endif
 
-        if (dictionary.TryGetValue(key, out var old))
+        if (dictionary.TryGetValue(key, out TValue? old))
         {
-            var update = updateValueFactory(key, old, factoryArgument);
+            var updated = updateValueFactory(key, old, factoryArgument);
-            dictionary[key] = update;
+            dictionary[key] = updated;
 
-            return update;
+            return updated;
         }
         else
         {

X10D/src/Collections/Int16Extensions.cs

@@ -22,7 +22,7 @@ public static class Int16Extensions
     [Pure]
     public static bool[] Unpack(this short value)
     {
-        bool[] ret = new bool[Size];
+        var ret = new bool[Size];
         value.Unpack(ret);
         return ret;
     }

X10D/src/Collections/Int32Extensions.cs

@@ -22,7 +22,7 @@ public static class Int32Extensions
     [Pure]
     public static bool[] Unpack(this int value)
     {
-        bool[] ret = new bool[Size];
+        var ret = new bool[Size];
         value.Unpack(ret);
         return ret;
     }
@@ -97,7 +97,7 @@ public static class Int32Extensions
                 var mask1Hi = Vector128.Create((byte)2, 2, 2, 2, 2, 2, 2, 2, 3, 3, 3, 3, 3, 3, 3, 3);
 
                 var one = Vector128.Create((byte)0x01);
-                
+
                 var vec = Vector128.Create(value).AsByte();
                 var shuffle = Ssse3.Shuffle(vec, mask1Lo);
                 var and = Sse2.AndNot(shuffle, mask2);

X10D/src/Collections/Int64Extensions.cs

@@ -17,7 +17,7 @@ public static class Int64Extensions
     [Pure]
     public static bool[] Unpack(this long value)
     {
-        bool[] ret = new bool[Size];
+        var ret = new bool[Size];
         value.Unpack(ret);
         return ret;
     }

X10D/src/Core/SpanExtensions.cs

@@ -2,6 +2,12 @@
 using System.Runtime.CompilerServices;
 using System.Runtime.InteropServices;
 
+#if NETCOREAPP3_0_OR_GREATER
+using System.Runtime.Intrinsics;
+using System.Runtime.Intrinsics.Arm;
+using System.Runtime.Intrinsics.X86;
+#endif
+
 namespace X10D.Core;
 
 /// <summary>
@@ -100,4 +106,93 @@ public static class SpanExtensions
         return false;
 #endif  // NET6_0_OR_GREATER
     }
+
+    /// <summary>
+    ///     Packs a <see cref="Span{T}"/> of booleans into a <see cref="byte" />.
+    /// </summary>
+    /// <param name="source">The span of booleans to pack.</param>
+    /// <returns>An 8-bit unsigned integer containing the packed booleans.</returns>
+    /// <exception cref="ArgumentException"><paramref name="source" /> contains more than 8 elements.</exception>
+    [Pure]
+    [MethodImpl(MethodImplOptions.AggressiveInlining)]
+    public static byte PackByte(this Span<bool> source)
+    {
+        return PackByte((ReadOnlySpan<bool>)source);
+    }
+
+    /// <summary>
+    ///     Packs a <see cref="ReadOnlySpan{T}"/> of booleans into a <see cref="byte" />.
+    /// </summary>
+    /// <param name="source">The span of booleans to pack.</param>
+    /// <returns>An 8-bit unsigned integer containing the packed booleans.</returns>
+    /// <exception cref="ArgumentException"><paramref name="source" /> contains more than 8 elements.</exception>
+    [Pure]
+    public static byte PackByte(this ReadOnlySpan<bool> source)
+    {
+        switch (source.Length)
+        {
+            case > 8: throw new ArgumentException("Source cannot contain more than 8 elements.", nameof(source));
+            case 8:
+#if NETSTANDARD2_1
+                // TODO: Think of a way to do fast boolean correctness.
+                goto default;
+#else
+                unsafe
+                {
+                    ulong reinterpret;
+
+                    // Boolean correctness.
+                    if (Sse2.IsSupported)
+                    {
+                        fixed (bool* pSource = source)
+                        {
+                            var vec = Sse2.LoadScalarVector128((ulong*)pSource).AsByte();
+                            var cmp = Sse2.CompareEqual(vec, Vector128<byte>.Zero);
+                            var correctness = Sse2.AndNot(cmp, Vector128.Create((byte)1));
+
+                            reinterpret = correctness.AsUInt64().GetElement(0);
+                        }
+                    }
+                    else if (AdvSimd.IsSupported)
+                    {
+                        // Haven't tested since March 6th 2023 (Reason: Unavailable hardware).
+                        fixed (bool* pSource = source)
+                        {
+                            var vec = AdvSimd.LoadVector64((byte*)pSource);
+                            var cmp = AdvSimd.CompareEqual(vec, Vector64<byte>.Zero);
+                            var correctness = AdvSimd.BitwiseSelect(cmp, vec, Vector64<byte>.Zero);
+
+                            reinterpret = Unsafe.As<Vector64<byte>, ulong>(ref correctness);
+                        }
+                    }
+                    else
+                    {
+                        goto default;
+                    }
+
+                    if (BitConverter.IsLittleEndian)
+                    {
+                        const ulong magic = 0b0000_0001_0000_0010_0000_0100_0000_1000_0001_0000_0010_0000_0100_0000_1000_0000;
+
+                        return unchecked((byte)(magic * reinterpret >> 56));
+                    }
+                    else
+                    {
+                        // Haven't tested since March 6th 2023 (Reason: Unavailable hardware).
+                        const ulong magic = 0b1000_0000_0100_0000_0010_0000_0001_0000_0000_1000_0000_0100_0000_0010_0000_0001;
+                        return unchecked((byte)(magic * reinterpret >> 56));
+                    }
+                }
+#endif
+            default:
+                byte result = 0;
+
+                for (var i = 0; i < source.Length; i++)
+                {
+                    result |= (byte)(source[i] ? 1 << i : 0);
+                }
+
+                return result;
+        }
+    }
 }

X10D/src/Drawing/ColorExtensions.cs

@@ -1,7 +1,6 @@
 using System.Diagnostics.Contracts;
 using System.Drawing;
 using System.Runtime.CompilerServices;
-using X10D.Collections;
 
 namespace X10D.Drawing;
 

X10D/src/Math/ComparableExtensions.cs

@@ -133,7 +133,7 @@ public static class ComparableExtensions
         if (lower.GreaterThan(upper))
         {
             throw new ArgumentException(
-                string.Format(null, ExceptionMessages.LowerCannotBeGreaterThanUpper, lower, upper),
+                string.Format(CultureInfo.CurrentCulture, ExceptionMessages.LowerCannotBeGreaterThanUpper, lower, upper),
                 nameof(lower));
         }
 

X10D/src/Reflection/MemberInfoExtensions.cs

@@ -37,7 +37,6 @@ public static class MemberInfoExtensions
             throw new ArgumentNullException(nameof(member));
         }
 #endif
-        
         return Attribute.IsDefined(member, typeof(T));
     }