From b9e59fc8d457975e9edf7fd0e39b6b1305f90f95 Mon Sep 17 00:00:00 2001
From: Pieter-Jan Briers <pieterjan.briers+git@gmail.com>
Date: Tue, 5 May 2020 23:58:56 +0200
Subject: [PATCH] Audio processing benchmarks.

---
 Content.Benchmarks/Program.cs               |  2 +-
 Content.Benchmarks/StereoToMonoBenchmark.cs | 70 +++++++++++++++++++++
 2 files changed, 71 insertions(+), 1 deletion(-)
 create mode 100644 Content.Benchmarks/StereoToMonoBenchmark.cs

diff --git a/Content.Benchmarks/Program.cs b/Content.Benchmarks/Program.cs
index 741a4efb33..7eb128092d 100644
--- a/Content.Benchmarks/Program.cs
+++ b/Content.Benchmarks/Program.cs
@@ -6,7 +6,7 @@ namespace Content.Benchmarks
     {
         public static void Main(string[] args)
         {
-            BenchmarkRunner.Run<ComponentManagerGetAllComponents>();
+            BenchmarkRunner.Run<StereoToMonoBenchmark>();
         }
     }
 }
diff --git a/Content.Benchmarks/StereoToMonoBenchmark.cs b/Content.Benchmarks/StereoToMonoBenchmark.cs
new file mode 100644
index 0000000000..89dec8a3dd
--- /dev/null
+++ b/Content.Benchmarks/StereoToMonoBenchmark.cs
@@ -0,0 +1,70 @@
+using System.Runtime.Intrinsics.X86;
+using BenchmarkDotNet.Attributes;
+
+namespace Content.Benchmarks
+{
+    public class StereoToMonoBenchmark
+    {
+        [Params(128, 256, 512)]
+        public int N { get; set; }
+
+        private short[] _input;
+        private short[] _output;
+
+        [GlobalSetup]
+        public void Setup()
+        {
+            _input = new short[N * 2];
+            _output = new short[N];
+        }
+
+        [Benchmark]
+        public void BenchSimple()
+        {
+            var l = N;
+            for (var j = 0; j < l; j++)
+            {
+                var k = j + l;
+                _output[j] = (short) ((_input[k] + _input[j]) / 2);
+            }
+        }
+
+        [Benchmark]
+        public unsafe void BenchSse()
+        {
+            var l = N;
+            fixed (short* iPtr = _input)
+            fixed (short* oPtr = _output)
+            {
+                for (var j = 0; j < l; j += 8)
+                {
+                    var k = j + l;
+
+                    var jV = Sse2.ShiftRightArithmetic(Sse2.LoadVector128(iPtr + j), 1);
+                    var kV = Sse2.ShiftRightArithmetic(Sse2.LoadVector128(iPtr + k), 1);
+
+                    Sse2.Store(j + oPtr, Sse2.Add(jV, kV));
+                }
+            }
+        }
+
+        [Benchmark]
+        public unsafe void BenchAvx2()
+        {
+            var l = N;
+            fixed (short* iPtr = _input)
+            fixed (short* oPtr = _output)
+            {
+                for (var j = 0; j < l; j += 16)
+                {
+                    var k = j + l;
+
+                    var jV = Avx2.ShiftRightArithmetic(Avx.LoadVector256(iPtr + j), 1);
+                    var kV = Avx2.ShiftRightArithmetic(Avx.LoadVector256(iPtr + k), 1);
+
+                    Avx.Store(j + oPtr, Avx2.Add(jV, kV));
+                }
+            }
+        }
+    }
+}