From 4c7c5b16940c29b2eff5de3c58e51b8c012ac481 Mon Sep 17 00:00:00 2001
From: Andrew Belt <andrewpbelt@gmail.com>
Date: Mon, 4 Jan 2021 08:23:51 -0500
Subject: [PATCH] Add auto engine sample rate setting.

---
 include/engine/Engine.hpp   |  3 ++-
 src/app/MenuBar.cpp         | 12 ++++++++++-
 src/core/AudioInterface.cpp |  2 +-
 src/engine/Engine.cpp       | 41 +++++++++++++++++++++++++------------
 src/settings.cpp            |  2 +-
 5 files changed, 43 insertions(+), 17 deletions(-)

diff --git a/include/engine/Engine.hpp b/include/engine/Engine.hpp
index e5d46f9d..c800596b 100644
--- a/include/engine/Engine.hpp
+++ b/include/engine/Engine.hpp
@@ -30,13 +30,14 @@ struct Engine {
 	/** Advances the engine by `frames` frames.
 	Only call this method from the primary module.
 	*/
-	void stepBlock(int frames);
+	void stepBlock(int frames, float suggestedSampleRate = 0.f);
 	void setPrimaryModule(Module* module);
 	Module* getPrimaryModule();
 
 	/** Returns the sample rate used by the engine for stepping each module.
 	*/
 	float getSampleRate();
+	PRIVATE void setSampleRate(float sampleRate);
 	/** Returns the inverse of the current sample rate.
 	*/
 	float getSampleTime();
diff --git a/src/app/MenuBar.cpp b/src/app/MenuBar.cpp
index f6e3b93d..e23e8383 100644
--- a/src/app/MenuBar.cpp
+++ b/src/app/MenuBar.cpp
@@ -492,6 +492,16 @@ struct SampleRateItem : ui::MenuItem {
 	ui::Menu* createChildMenu() override {
 		ui::Menu* menu = new ui::Menu;
 
+		SampleRateValueItem* autoItem = new SampleRateValueItem;
+		autoItem->sampleRate = 0;
+		autoItem->text = "Auto";
+		if (settings::sampleRate == 0) {
+			float sampleRate = APP->engine->getSampleRate();
+			autoItem->rightText = string::f("(%g kHz) ", sampleRate / 1000.f);
+			autoItem->rightText += CHECKMARK_STRING;
+		}
+		menu->addChild(autoItem);
+
 		for (int i = -2; i <= 4; i++) {
 			for (int j = 0; j < 2; j++) {
 				float oversample = std::pow(2.f, i);
@@ -500,7 +510,7 @@ struct SampleRateItem : ui::MenuItem {
 
 				SampleRateValueItem* item = new SampleRateValueItem;
 				item->sampleRate = sampleRate;
-				item->text = string::f("%g kHz", sampleRate / 1000.0);
+				item->text = string::f("%g kHz", sampleRate / 1000.f);
 				if (oversample > 1.f) {
 					item->rightText += string::f("(%.0fx)", oversample);
 				}
diff --git a/src/core/AudioInterface.cpp b/src/core/AudioInterface.cpp
index 9f3063d9..cd92469d 100644
--- a/src/core/AudioInterface.cpp
+++ b/src/core/AudioInterface.cpp
@@ -245,7 +245,7 @@ struct AudioInterface : Module, audio::Port {
 		bool isPrimary = (APP->engine->getPrimaryModule() == this);
 		// Step engine
 		if (isPrimary && requestedEngineFrames > 0) {
-			APP->engine->stepBlock(requestedEngineFrames);
+			APP->engine->stepBlock(requestedEngineFrames, getSampleRate());
 		}
 	}
 
diff --git a/src/engine/Engine.cpp b/src/engine/Engine.cpp
index 845ad18f..d9230a95 100644
--- a/src/engine/Engine.cpp
+++ b/src/engine/Engine.cpp
@@ -182,6 +182,9 @@ struct EngineWorker {
 };
 
 
+static const float FALLBACK_SAMPLE_RATE = 44100;
+
+
 struct Engine::Internal {
 	std::vector<Module*> modules;
 	std::vector<Cable*> cables;
@@ -453,8 +456,7 @@ Engine::Engine() {
 	internal = new Internal;
 
 	internal->context = contextGet();
-	internal->sampleRate = 44100.f;
-	internal->sampleTime = 1 / internal->sampleRate;
+	setSampleRate(FALLBACK_SAMPLE_RATE);
 }
 
 
@@ -498,7 +500,7 @@ void Engine::clear() {
 }
 
 
-void Engine::stepBlock(int frames) {
+void Engine::stepBlock(int frames, float suggestedSampleRate) {
 	std::lock_guard<std::mutex> stepLock(internal->blockMutex);
 	SharedLock lock(internal->mutex);
 	// Configure thread
@@ -510,16 +512,14 @@ void Engine::stepBlock(int frames) {
 	internal->blockFrames = frames;
 
 	// Set sample rate
-	if (internal->sampleRate != settings::sampleRate) {
-		internal->sampleRate = settings::sampleRate;
-		internal->sampleTime = 1.f / internal->sampleRate;
-		// Trigger SampleRateChangeEvent
-		Module::SampleRateChangeEvent e;
-		e.sampleRate = internal->sampleRate;
-		e.sampleTime = internal->sampleTime;
-		for (Module* module : internal->modules) {
-			module->onSampleRateChange(e);
-		}
+	if (settings::sampleRate > 0) {
+		setSampleRate(settings::sampleRate);
+	}
+	else if (suggestedSampleRate > 0) {
+		setSampleRate(suggestedSampleRate);
+	}
+	else {
+		setSampleRate(FALLBACK_SAMPLE_RATE);
 	}
 
 	// Update expander pointers
@@ -570,6 +570,21 @@ float Engine::getSampleRate() {
 }
 
 
+void Engine::setSampleRate(float sampleRate) {
+	if (sampleRate == internal->sampleRate)
+		return;
+	internal->sampleRate = sampleRate;
+	internal->sampleTime = 1.f / sampleRate;
+	// Trigger SampleRateChangeEvent
+	Module::SampleRateChangeEvent e;
+	e.sampleRate = internal->sampleRate;
+	e.sampleTime = internal->sampleTime;
+	for (Module* module : internal->modules) {
+		module->onSampleRateChange(e);
+	}
+}
+
+
 float Engine::getSampleTime() {
 	return internal->sampleTime;
 }
diff --git a/src/settings.cpp b/src/settings.cpp
index ff18861b..150930f9 100644
--- a/src/settings.cpp
+++ b/src/settings.cpp
@@ -26,7 +26,7 @@ float cableTension = 0.5;
 bool allowCursorLock = true;
 KnobMode knobMode = KNOB_MODE_LINEAR;
 float knobLinearSensitivity = 0.001f;
-float sampleRate = 44100.0;
+float sampleRate = 0;
 int threadCount = 1;
 bool tooltips = true;
 bool cpuMeter = false;