Optimize EncodeBase83

Bond-009 · Jul 3, 2023 · 5275ad3 · 5275ad3
1 parent 90bad6d
commit 5275ad3
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Showing 7 changed files with 69 additions and 26 deletions.
diff --git a/BlurHashSharp.sln b/BlurHashSharp.sln
@@ -15,6 +15,10 @@ Project("{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}") = "BlurHashSharp.Tests", "test
 EndProject
 Project("{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}") = "BlurHashSharp.SkiaSharp.Tests", "tests\BlurHashSharp.SkiaSharp.Tests\BlurHashSharp.SkiaSharp.Tests.csproj", "{B075D075-93C4-4A19-8657-773593308FD4}"
 EndProject
+Project("{2150E333-8FDC-42A3-9474-1A3956D46DE8}") = "benches", "benches", "{16AA13F8-F18E-4C4D-98B9-B45E9E659E5B}"
+EndProject
+Project("{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}") = "BlurHashSharp.Benches", "benches\BlurHashSharp.Benches\BlurHashSharp.Benches.csproj", "{E34874CB-32B1-402D-8E3C-071676468135}"
+EndProject
 Global
 	GlobalSection(SolutionConfigurationPlatforms) = preSolution
 		Debug|Any CPU = Debug|Any CPU
@@ -76,11 +80,24 @@ Global
 		{B075D075-93C4-4A19-8657-773593308FD4}.Release|x64.Build.0 = Release|Any CPU
 		{B075D075-93C4-4A19-8657-773593308FD4}.Release|x86.ActiveCfg = Release|Any CPU
 		{B075D075-93C4-4A19-8657-773593308FD4}.Release|x86.Build.0 = Release|Any CPU
+		{E34874CB-32B1-402D-8E3C-071676468135}.Debug|Any CPU.ActiveCfg = Debug|Any CPU
+		{E34874CB-32B1-402D-8E3C-071676468135}.Debug|Any CPU.Build.0 = Debug|Any CPU
+		{E34874CB-32B1-402D-8E3C-071676468135}.Debug|x64.ActiveCfg = Debug|Any CPU
+		{E34874CB-32B1-402D-8E3C-071676468135}.Debug|x64.Build.0 = Debug|Any CPU
+		{E34874CB-32B1-402D-8E3C-071676468135}.Debug|x86.ActiveCfg = Debug|Any CPU
+		{E34874CB-32B1-402D-8E3C-071676468135}.Debug|x86.Build.0 = Debug|Any CPU
+		{E34874CB-32B1-402D-8E3C-071676468135}.Release|Any CPU.ActiveCfg = Release|Any CPU
+		{E34874CB-32B1-402D-8E3C-071676468135}.Release|Any CPU.Build.0 = Release|Any CPU
+		{E34874CB-32B1-402D-8E3C-071676468135}.Release|x64.ActiveCfg = Release|Any CPU
+		{E34874CB-32B1-402D-8E3C-071676468135}.Release|x64.Build.0 = Release|Any CPU
+		{E34874CB-32B1-402D-8E3C-071676468135}.Release|x86.ActiveCfg = Release|Any CPU
+		{E34874CB-32B1-402D-8E3C-071676468135}.Release|x86.Build.0 = Release|Any CPU
 	EndGlobalSection
 	GlobalSection(NestedProjects) = preSolution
 		{680BD7F7-37FA-44B3-8297-91C6EF00A870} = {22515C2C-F86B-404F-A0B0-60F0B8FE9B8C}
 		{2422C8A8-5121-4BA4-8B8F-F8D00C659E98} = {22515C2C-F86B-404F-A0B0-60F0B8FE9B8C}
 		{EA7DE5B7-8A37-4BF1-B10A-7CE7B982CD8A} = {AA9B09A6-896C-4CB8-8B56-7AA05697B218}
 		{B075D075-93C4-4A19-8657-773593308FD4} = {AA9B09A6-896C-4CB8-8B56-7AA05697B218}
+		{E34874CB-32B1-402D-8E3C-071676468135} = {16AA13F8-F18E-4C4D-98B9-B45E9E659E5B}
 	EndGlobalSection
 EndGlobal
diff --git a/benches/BlurHashSharp.Benches/BlurHashSharp.Benches.csproj b/benches/BlurHashSharp.Benches/BlurHashSharp.Benches.csproj
@@ -2,12 +2,12 @@
 
   <PropertyGroup>
     <OutputType>Exe</OutputType>
-    <TargetFramework>net5.0</TargetFramework>
+    <TargetFramework>net7.0</TargetFramework>
     <AllowUnsafeBlocks>true</AllowUnsafeBlocks>
   </PropertyGroup>
 
   <ItemGroup>
-    <PackageReference Include="BenchmarkDotNet" Version="0.12.1" />
+    <PackageReference Include="BenchmarkDotNet" Version="0.13.5" />
   </ItemGroup>
 
   <ItemGroup>

diff --git a/benches/BlurHashSharp.Benches/EncodeBase83Benches.cs b/benches/BlurHashSharp.Benches/EncodeBase83Benches.cs
@@ -0,0 +1,27 @@
+using System;
+using BenchmarkDotNet.Attributes;
+
+namespace BlurHashSharp.Benches
+{
+    [MemoryDiagnoser]
+    public class EncodeBase83Benches
+    {
+        private int _data;
+
+        [Params(1, 2, 4)]
+        public int N { get; set; }
+
+        [GlobalSetup]
+        public void GlobalSetup()
+        {
+            _data = new Random(42).Next();
+        }
+
+        [Benchmark]
+        public void EncodeBase83()
+        {
+            Span<char> dest = stackalloc char[4];
+            CoreBlurHashEncoder.EncodeBase83(_data, N, dest);
+        }
+    }
+}
diff --git a/benches/BlurHashSharp.Benches/MaxBenches.cs b/benches/BlurHashSharp.Benches/MaxBenches.cs
@@ -1,8 +1,6 @@
 using System;
-using System.IO;
 using System.Linq;
 using BenchmarkDotNet.Attributes;
-using BenchmarkDotNet.Running;
 
 namespace BlurHashSharp.Benches
 {

diff --git a/benches/BlurHashSharp.Benches/PrecomputeCosinesBenches.cs b/benches/BlurHashSharp.Benches/PrecomputeCosinesBenches.cs
@@ -1,8 +1,5 @@
 using System;
-using System.IO;
-using System.Linq;
 using BenchmarkDotNet.Attributes;
-using BenchmarkDotNet.Running;
 
 namespace BlurHashSharp.Benches
 {
@@ -21,9 +18,9 @@ public void GlobalSetup()
         }
 
         [Benchmark]
-        public void PrecomputeCosines() => CoreBlurHashEncoder.PrecomputeCosines(_data, N, MathF.PI / N);
+        public void PrecomputeCosines() => CoreBlurHashEncoder.PrecomputeCosines(_data, MathF.PI / N);
 
         [Benchmark]
-        public void PrecomputeCosinesZero() => CoreBlurHashEncoder.PrecomputeCosines(_data, N, 0f);
+        public void PrecomputeCosinesZero() => CoreBlurHashEncoder.PrecomputeCosines(_data, 0f);
     }
 }
diff --git a/benches/BlurHashSharp.Benches/Program.cs b/benches/BlurHashSharp.Benches/Program.cs
@@ -1,5 +1,4 @@
-using System;
-using BenchmarkDotNet.Running;
+using BenchmarkDotNet.Running;
 
 namespace BlurHashSharp.Benches
 {
@@ -8,7 +7,8 @@ public static class Program
         public static void Main(string[] args)
         {
             // _ = BenchmarkRunner.Run<MaxBenches>();
-            _ = BenchmarkRunner.Run<PrecomputeCosinesBenches>();
+            // _ = BenchmarkRunner.Run<PrecomputeCosinesBenches>();
+            _ = BenchmarkRunner.Run<EncodeBase83Benches>();
         }
     }
 }
diff --git a/src/BlurHashSharp/CoreBlurHashEncoder.cs b/src/BlurHashSharp/CoreBlurHashEncoder.cs
@@ -1,4 +1,9 @@
 using System;
+using System.Runtime.CompilerServices;
+using System.Diagnostics;
+using System.Runtime.Intrinsics;
+using System.Runtime.Intrinsics.Arm;
+using System.Runtime.Intrinsics.X86;
 
 namespace BlurHashSharp
 {
@@ -121,11 +126,11 @@ static int ThrowPixelFormatArgumentException()
 
             for (int yC = 0; yC < yComponents; yC++)
             {
-                PrecomputeCosines(cosYLookup, height, MathF.PI * yC / height);
+                PrecomputeCosines(cosYLookup, MathF.PI * yC / height);
 
                 for (int xC = 0; xC < xComponents; xC++)
                 {
-                    PrecomputeCosines(cosXLookup, width, MathF.PI * xC / width);
+                    PrecomputeCosines(cosXLookup, MathF.PI * xC / width);
 
                     float c1 = 0;
                     float c2 = 0;
@@ -209,7 +214,7 @@ static int ThrowPixelFormatArgumentException()
             });
         }
 
-        internal static void PrecomputeCosines(Span<float> table, int count, float offset)
+        internal static void PrecomputeCosines(Span<float> table, float offset)
         {
             if (offset == 0f)
             {
@@ -218,7 +223,7 @@ internal static void PrecomputeCosines(Span<float> table, int count, float offse
             }
 
             float coef = 0f;
-            for (int i = 0; i < count; i++)
+            for (int i = 0; i < table.Length; i++)
             {
                 table[i] = MathF.Cos(coef);
                 coef += offset;
@@ -260,20 +265,19 @@ internal static float SignSqrtF(float value)
 
         internal static int EncodeBase83(int value, int length, Span<char> destination)
         {
+            const int Base = 83;
             const string Characters = @"0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz#$%*+,-.:;=?@[]^_{|}~";
-            int divisor = 1;
 
-            int i = 0;
-            for (; i < length - 1; i++)
-            {
-                divisor *= 83;
-            }
+            Debug.Assert(Base == Characters.Length);
+            Debug.Assert(length <= destination.Length);
+
+            destination[length - 1] = Characters[value % Base];
 
-            for (i = 0; i < length; i++)
+            int tmpValue = value;
+            for (int i = length - 2; i >= 0; i--)
             {
-                int digit = (value / divisor) % 83;
-                divisor /= 83;
-                destination[i] = Characters[digit];
+                tmpValue /= Base;
+                destination[i] = Characters[tmpValue % Base];
             }
 
             return length;