Use SIMD acceleration for audio upsampler (#4410)

* Use SIMD acceleration for audio upsampler filter kernel for a moderate speedup

* Address formatting. Implement AVX2 fast path for high quality resampling in ResamplerHelper

* now really, are we really getting the benefit of inlining 50+ line methods?

* adding unit tests for resampler + upsampler. The upsampler ones fail for some reason

* Fixing upsampler test. Apparently this algo only works at specific ratios

---------

Co-authored-by: Logan Stromberg <lostromb@microsoft.com>

Ryujinx.Tests/Audio/Renderer/Dsp/ResamplerTests.cs

@@ -0,0 +1,93 @@
+using NUnit.Framework;
+using Ryujinx.Audio.Renderer.Dsp;
+using Ryujinx.Audio.Renderer.Parameter;
+using Ryujinx.Audio.Renderer.Server.Upsampler;
+using System;
+using System.Collections.Generic;
+using System.IO;
+using System.Linq;
+using System.Runtime.CompilerServices;
+using System.Text;
+using System.Threading.Tasks;
+
+namespace Ryujinx.Tests.Audio.Renderer.Dsp
+{
+    class ResamplerTests
+    {
+        [Test]
+        [TestCase(VoiceInParameter.SampleRateConversionQuality.Low)]
+        [TestCase(VoiceInParameter.SampleRateConversionQuality.Default)]
+        [TestCase(VoiceInParameter.SampleRateConversionQuality.High)]
+        public void TestResamplerConsistencyUpsampling(VoiceInParameter.SampleRateConversionQuality quality)
+        {
+            DoResamplingTest(44100, 48000, quality);
+        }
+
+        [Test]
+        [TestCase(VoiceInParameter.SampleRateConversionQuality.Low)]
+        [TestCase(VoiceInParameter.SampleRateConversionQuality.Default)]
+        [TestCase(VoiceInParameter.SampleRateConversionQuality.High)]
+        public void TestResamplerConsistencyDownsampling(VoiceInParameter.SampleRateConversionQuality quality)
+        {
+            DoResamplingTest(48000, 44100, quality);
+        }
+
+        /// <summary>
+        /// Generates a 1-second sine wave sample at input rate, resamples it to output rate, and
+        /// ensures that it resampled at the expected rate with no discontinuities
+        /// </summary>
+        /// <param name="inputRate">The input sample rate to test</param>
+        /// <param name="outputRate">The output sample rate to test</param>
+        /// <param name="quality">The resampler quality to use</param>
+        private static void DoResamplingTest(int inputRate, int outputRate, VoiceInParameter.SampleRateConversionQuality quality)
+        {
+            float inputSampleRate = (float)inputRate;
+            float outputSampleRate = (float)outputRate;
+            int inputSampleCount = inputRate;
+            int outputSampleCount = outputRate;
+            short[] inputBuffer = new short[inputSampleCount + 100]; // add some safety buffer at the end
+            float[] outputBuffer = new float[outputSampleCount + 100];
+            for (int sample = 0; sample < inputBuffer.Length; sample++)
+            {
+                // 440 hz sine wave with amplitude = 0.5f at input sample rate
+                inputBuffer[sample] = (short)(32767 * MathF.Sin((440 / inputSampleRate) * (float)sample * MathF.PI * 2f) * 0.5f);
+            }
+
+            float fraction = 0;
+
+            ResamplerHelper.Resample(
+                outputBuffer.AsSpan(),
+                inputBuffer.AsSpan(),
+                inputSampleRate / outputSampleRate,
+                ref fraction,
+                outputSampleCount,
+                quality,
+                false);
+
+            float[] expectedOutput = new float[outputSampleCount];
+            float sumDifference = 0;
+            int delay = quality switch
+            {
+                VoiceInParameter.SampleRateConversionQuality.High => 3,
+                VoiceInParameter.SampleRateConversionQuality.Default => 1,
+                _ => 0
+            };
+
+            for (int sample = 0; sample < outputSampleCount; sample++)
+            {
+                outputBuffer[sample] /= 32767;
+                // 440 hz sine wave with amplitude = 0.5f at output sample rate
+                expectedOutput[sample] = MathF.Sin((440 / outputSampleRate) * (float)(sample + delay) * MathF.PI * 2f) * 0.5f;
+                float thisDelta = Math.Abs(expectedOutput[sample] - outputBuffer[sample]);
+
+                // Ensure no discontinuities
+                Assert.IsTrue(thisDelta < 0.1f);
+                sumDifference += thisDelta;
+            }
+
+            sumDifference = sumDifference / (float)outputSampleCount;
+            // Expect the output to be 99% similar to the expected resampled sine wave
+            Assert.IsTrue(sumDifference < 0.01f);
+        }
+    }
+}