feat(#161): Drop netstandard2.0 target, support net8.0+ only

HdrHistogram.Benchmarking/LeadingZeroCount/LeadingZeroCountBenchmarkBase.cs

@@ -39,7 +39,7 @@
             var source = GenerateTestData(maxBit);
 
             _testValues = source
                 .Skip(Math.Max(0, source.Count() - TEST_VALUE_LENGTH))
                 .Select(d => d.Value)
                 .ToArray();
 
@@ -53,7 +53,6 @@
             var functions = new Dictionary<string, Func<long, int>>
             {
                 {"CurrentImpl", Bitwise.NumberOfLeadingZeros},
-                {"Imperative", Bitwise.Imperative.NumberOfLeadingZeros},
                 {"IfAndShift", LeadingZeroCount.IfAndShift.GetLeadingZeroCount},
                 //{"MathLog", LeadingZeroCount.MathLog.GetLeadingZeroCount},
                 {"StringManipulation", LeadingZeroCount.StringManipulation.GetLeadingZeroCount},
@@ -121,17 +120,6 @@
             return sum;
         }
 
-        [Benchmark(OperationsPerInvoke = TEST_VALUE_LENGTH)]
-        public int ImperativeImplementation()
-        {
-            var sum = 0;
-            for (int i = 0; i < _testValues.Length; i++)
-            {
-                sum += Bitwise.Imperative.NumberOfLeadingZeros(_testValues[i]);
-            }
-            return sum;
-        }
-
         [Benchmark(OperationsPerInvoke = TEST_VALUE_LENGTH)]
         public int IfAndShift()
         {
@@ -198,7 +186,7 @@
             return sum;
         }
         [Benchmark(OperationsPerInvoke = TEST_VALUE_LENGTH)]
         public int BBarry_imp1()
         {
             var sum = 0;
             for (int i = 0; i < _testValues.Length; i++)
@@ -208,7 +196,7 @@
             return sum;
         }
         [Benchmark(OperationsPerInvoke = TEST_VALUE_LENGTH)]
         public int BBarry_imp2()
         {
             var sum = 0;
             for (int i = 0; i < _testValues.Length; i++)
@@ -218,7 +206,7 @@
             return sum;
         }
         [Benchmark(OperationsPerInvoke = TEST_VALUE_LENGTH)]
         public int BBarry_imp3()
         {
             var sum = 0;
             for (int i = 0; i < _testValues.Length; i++)
@@ -228,7 +216,7 @@
             return sum;
         }
         [Benchmark(OperationsPerInvoke = TEST_VALUE_LENGTH)]
         public int BBarry_imp4()
         {
             var sum = 0;
             for (int i = 0; i < _testValues.Length; i++)
@@ -239,7 +227,7 @@
         }
 
 
         private class CalculationExpectation
         {
             public long Value { get; }
             public int Expected { get; }

HdrHistogram.UnitTests/Utilities/BitwiseTests.cs

@@ -0,0 +1,45 @@
+/*
+ * This is a .NET port of the original Java version, which was written by
+ * Gil Tene as described in
+ * https://github.com/HdrHistogram/HdrHistogram
+ * and released to the public domain, as explained at
+ * http://creativecommons.org/publicdomain/zero/1.0/
+ */
+
+using HdrHistogram.Utilities;
+using Xunit;
+
+namespace HdrHistogram.UnitTests.Utilities
+{
+    public class BitwiseTests
+    {
+        [Theory]
+        [InlineData(0L, 64)]
+        [InlineData(1L, 63)]
+        [InlineData(2L, 62)]
+        [InlineData(4L, 61)]
+        [InlineData(8L, 60)]
+        [InlineData(16L, 59)]
+        [InlineData(32L, 58)]
+        [InlineData(64L, 57)]
+        [InlineData(128L, 56)]
+        [InlineData(256L, 55)]
+        [InlineData(512L, 54)]
+        [InlineData(1024L, 53)]
+        [InlineData(2048L, 52)]
+        [InlineData(4096L, 51)]
+        [InlineData(8192L, 50)]
+        [InlineData(16384L, 49)]
+        [InlineData(32768L, 48)]
+        [InlineData(65536L, 47)]
+        [InlineData(1L << 30, 33)]
+        [InlineData(1L << 31, 32)]
+        [InlineData(1L << 32, 31)]
+        [InlineData(1L << 62, 1)]
+        [InlineData(long.MaxValue, 1)]
+        public void NumberOfLeadingZeros_ReturnsCorrectValue(long value, int expected)
+        {
+            Assert.Equal(expected, Bitwise.NumberOfLeadingZeros(value));
+        }
+    }
+}

HdrHistogram/HdrHistogram.csproj

@@ -1,7 +1,7 @@
-<Project Sdk="Microsoft.NET.Sdk">
+<Project Sdk="Microsoft.NET.Sdk">
 
   <PropertyGroup>
-    <TargetFrameworks>net10.0;net9.0;net8.0;netstandard2.0</TargetFrameworks>
+    <TargetFrameworks>net10.0;net9.0;net8.0</TargetFrameworks>
     <Description>HdrHistogram supports low latency recording and analyzing of sampled data value counts across a configurable integer value range with configurable value precision within the range.</Description>
     <Authors>Gil Tene, Lee Campbell</Authors>
     <PackageReleaseNotes>Net 8.0 release</PackageReleaseNotes>
@@ -21,21 +21,8 @@
     <None Include="../README.md" Pack="true" PackagePath="" />
   </ItemGroup>
 
-  <PropertyGroup Condition="'$(Configuration)|$(TargetFramework)|$(Platform)'=='Release|net8.0|AnyCPU'">
-    <DocumentationFile>bin\Release\net8.0\HdrHistogram.xml</DocumentationFile>
+  <PropertyGroup Condition="'$(Configuration)' == 'Release'">
+    <DocumentationFile>bin\Release\$(TargetFramework)\HdrHistogram.xml</DocumentationFile>
   </PropertyGroup>
 
-  <PropertyGroup Condition="'$(Configuration)|$(TargetFramework)|$(Platform)'=='Release|net9.0|AnyCPU'">
-    <DocumentationFile>bin\Release\net9.0\HdrHistogram.xml</DocumentationFile>
-  </PropertyGroup>
-
-  <PropertyGroup Condition="'$(Configuration)|$(TargetFramework)|$(Platform)'=='Release|net10.0|AnyCPU'">
-    <DocumentationFile>bin\Release\net10.0\HdrHistogram.xml</DocumentationFile>
-  </PropertyGroup>
-
-  <PropertyGroup Condition="'$(Configuration)|$(TargetFramework)|$(Platform)'=='Release|netstandard2.0|AnyCPU'">
-    <DocumentationFile>bin\Release\netstandard2.0\HdrHistogram.xml</DocumentationFile>
-    <DefineConstants>RELEASE;NETSTANDARD2_0</DefineConstants>
-  </PropertyGroup>
-
-</Project>
+</Project>

HdrHistogram/HistogramLogReader.cs

@@ -240,11 +240,7 @@ private IEnumerable<string> ReadLines()
 
         private static bool IsComment(string line)
         {
-#if NETSTANDARD2_0
-            return line.StartsWith("#", StringComparison.Ordinal);
-#else
             return line.StartsWith('#');
-#endif
         }
 
         private static bool IsStartTime(string line)

HdrHistogram/Utilities/Bitwise.cs

@@ -22,90 +22,7 @@ public static class Bitwise
         /// <returns>The number of leading zeros.</returns>
         public static int NumberOfLeadingZeros(long value)
         {
-#if NET5_0_OR_GREATER
-            return IntrinsicNumberOfLeadingZeros(value);
-#else
-            return Imperative.NumberOfLeadingZeros(value);
-#endif
-        }
-
-#if NET5_0_OR_GREATER
-        /// <summary>
-        /// Returns the Leading Zero Count (lzc) of the <paramref name="value"/> for its binary representation.
-        /// </summary>
-        /// <param name="value">The value to find the number of leading zeros</param>
-        /// <returns>The number of leading zeros.</returns>
-        private static int IntrinsicNumberOfLeadingZeros(long value)
-        {
-            ulong testValue = (ulong)value;
-            return System.Numerics.BitOperations.LeadingZeroCount(testValue);
-
-        }
-#endif
-
-        //Code has been tested and taken from :
-        //http://stackoverflow.com/questions/9543410/i-dont-think-numberofleadingzeroslong-i-in-long-java-is-based-floorlog2x/9543537#9543537
-        //http://stackoverflow.com/questions/21888140/de-bruijn-algorithm-binary-digit-count-64bits-c-sharp/21888542#21888542
-        //http://stackoverflow.com/questions/15967240/fastest-implementation-of-log2int-and-log2float
-        //http://graphics.stanford.edu/~seander/bithacks.html#IntegerLogObvious
-
-        /// <summary>
-        /// Imperative implementation of the LeadingZeroCount, when access to the <c>System.Numerics.BitOperations.LeadingZeroCount(ulong)</c> is not available.
-        /// </summary>
-        public static class Imperative
-        {
-            private static readonly int[] Lookup;
-
-            static Imperative()
-            {
-                Lookup = new int[256];
-                for (int i = 1; i < 256; ++i)
-                {
-                    Lookup[i] = (int)(Math.Log(i) / Math.Log(2));
-                }
-            }
-
-            /// <summary>
-            /// Returns the Leading Zero Count (lzc) of the <paramref name="value"/> for its binary representation.
-            /// </summary>
-            /// <param name="value">The value to find the number of leading zeros</param>
-            /// <returns>The number of leading zeros.</returns>
-            public static int NumberOfLeadingZeros(long value)
-            {
-                //Optimisation for 32 bit values. So values under 00:16:41.0 when measuring with Stopwatch.GetTimestamp()*, we will hit a fast path.
-                //  * as at writing on Win10 .NET 4.6
-                if (value < int.MaxValue)
-                    return 63 - Log2((int)value);
-                return NumberOfLeadingZerosLong(value);
-            }
-
-            private static int NumberOfLeadingZerosLong(long value)
-            {
-                // Code from http://stackoverflow.com/questions/9543410/i-dont-think-numberofleadingzeroslong-i-in-long-java-is-based-floorlog2x/9543537#9543537
-
-                //--Already checked that values here are over int.MaxValue, i.e. !=0
-                // HD, Figure 5-6
-                //if (value == 0)
-                //    return 64;
-                var n = 1;
-                // >>> in Java is a "unsigned bit shift", to do the same in C# we use >> (but it HAS to be an unsigned int)
-                var x = (uint)(value >> 32);
-                if (x == 0) { n += 32; x = (uint)value; }
-                if (x >> 16 == 0) { n += 16; x <<= 16; }
-                if (x >> 24 == 0) { n += 8; x <<= 8; }
-                if (x >> 28 == 0) { n += 4; x <<= 4; }
-                if (x >> 30 == 0) { n += 2; x <<= 2; }
-                n -= (int)(x >> 31);
-                return n;
-            }
-
-            private static int Log2(int i)
-            {
-                if (i >= 0x1000000) { return Lookup[i >> 24] + 24; }
-                if (i >= 0x10000) { return Lookup[i >> 16] + 16; }
-                if (i >= 0x100) { return Lookup[i >> 8] + 8; }
-                return Lookup[i];
-            }
+            return System.Numerics.BitOperations.LeadingZeroCount((ulong)value);
         }
     }
 }

spec/tech-standards/build-system.md

@@ -22,15 +22,14 @@ HdrHistogram.sln
 ### Main Library (HdrHistogram.csproj)
 
 ```xml
-<TargetFrameworks>net10.0;net9.0;net8.0;netstandard2.0</TargetFrameworks>
+<TargetFrameworks>net10.0;net9.0;net8.0</TargetFrameworks>
 ```
 
 | Target | Description |
 |--------|-------------|
 | `net10.0` | Modern .NET (current LTS target) |
 | `net9.0` | Modern .NET (STS target) |
 | `net8.0` | Modern .NET (LTS target) |
-| `netstandard2.0` | Broad compatibility (.NET Framework 4.6.1+, .NET Core 2.0+) |
 
 ### Test Project