From d66b70f3a2edc7f294fb0b1c0adb4a6318ef658a Mon Sep 17 00:00:00 2001
From: Robin Gareus <robin@gareus.org>
Date: Fri, 2 Jun 2023 21:44:36 +0200
Subject: [PATCH] Distinct engine-states per sample-rate

Previously only the one engine-state per device was
saved. However systemic latency depends on the sample-rate
(and buffersize)
---
 gtk2_ardour/engine_dialog.cc | 48 +++++++++++++++++++++++++-----------
 gtk2_ardour/engine_dialog.h  | 11 ++++++---
 2 files changed, 41 insertions(+), 18 deletions(-)

diff --git a/gtk2_ardour/engine_dialog.cc b/gtk2_ardour/engine_dialog.cc
index 45af3c5d4f..6871e1e3f2 100644
--- a/gtk2_ardour/engine_dialog.cc
+++ b/gtk2_ardour/engine_dialog.cc
@@ -1778,12 +1778,20 @@ EngineControl::State
 EngineControl::get_matching_state (
     const string& backend,
     const string& driver,
-    const string& device)
+    const string& device,
+    const float   sample_rate)
 {
-	for (StateList::iterator i = states.begin (); i != states.end (); ++i) {
-		if ((*i)->backend == backend &&
-		    (!_have_control || ((*i)->driver == driver && (*i)->device == device))) {
-			return (*i);
+	for (auto const& i : states) {
+		if (i->backend != backend) {
+			continue;
+		}
+		if (!_have_control) {
+			return i;
+		}
+		if (i->driver == driver && i->device == device) {
+			if (sample_rate == 0 || i->sample_rate == sample_rate) {
+				return i;
+			}
 		}
 	}
 	return State ();
@@ -1794,12 +1802,20 @@ EngineControl::get_matching_state (
     const string& backend,
     const string& driver,
     const string& input_device,
-    const string& output_device)
+    const string& output_device,
+    const float   sample_rate)
 {
-	for (StateList::iterator i = states.begin (); i != states.end (); ++i) {
-		if ((*i)->backend == backend &&
-		    (!_have_control || ((*i)->driver == driver && ((*i)->input_device == input_device) && (*i)->output_device == output_device))) {
-			return (*i);
+	for (auto const& i : states) {
+		if (i->backend != backend) {
+			continue;
+		}
+		if (!_have_control) {
+			return i;
+		}
+		if (i->driver == driver && i->input_device == input_device && i->output_device == output_device) {
+			if (sample_rate == 0 || i->sample_rate == sample_rate) {
+				return i;
+			}
 		}
 	}
 	return State ();
@@ -1815,17 +1831,20 @@ EngineControl::get_saved_state_for_currently_displayed_backend_and_device ()
 			return get_matching_state (backend_combo.get_active_text (),
 			                           (backend->requires_driver_selection () ? (std::string)driver_combo.get_active_text () : string ()),
 			                           input_device_combo.get_active_text (),
-			                           output_device_combo.get_active_text ());
+			                           output_device_combo.get_active_text (),
+			                           get_rate ());
 		} else {
 			return get_matching_state (backend_combo.get_active_text (),
 			                           (backend->requires_driver_selection () ? (std::string)driver_combo.get_active_text () : string ()),
-			                           device_combo.get_active_text ());
+			                           device_combo.get_active_text (),
+			                           get_rate ());
 		}
 	}
 
 	return get_matching_state (backend_combo.get_active_text (),
 	                           string (),
-	                           device_combo.get_active_text ());
+	                           device_combo.get_active_text (),
+	                           get_rate ());
 }
 
 bool
@@ -1836,7 +1855,8 @@ EngineControl::equivalent_states (const EngineControl::State& state1,
 	    state1->driver == state2->driver &&
 	    state1->device == state2->device &&
 	    state1->input_device == state2->input_device &&
-	    state1->output_device == state2->output_device) {
+	    state1->output_device == state2->output_device &&
+	    state1->sample_rate == state2->sample_rate) {
 		return true;
 	}
 	return false;
diff --git a/gtk2_ardour/engine_dialog.h b/gtk2_ardour/engine_dialog.h
index 86c7e55474..b8ba0a2c4a 100644
--- a/gtk2_ardour/engine_dialog.h
+++ b/gtk2_ardour/engine_dialog.h
@@ -271,6 +271,7 @@ private:
 		StateStruct ()
 		    : sample_rate (48000)
 		    , buffer_size (1024)
+		    , n_periods (0)
 		    , input_latency (0)
 		    , output_latency (0)
 		    , active (false)
@@ -281,8 +282,8 @@ private:
 	};
 
 	typedef std::shared_ptr<StateStruct> State;
-	typedef std::list<State>               StateList;
-	static bool                            state_sort_cmp (const State& a, const State& b);
+	typedef std::list<State>             StateList;
+	static bool                          state_sort_cmp (const State& a, const State& b);
 
 	StateList states;
 
@@ -290,11 +291,13 @@ private:
 
 	State get_matching_state (const std::string& backend,
 	                          const std::string& driver,
-	                          const std::string& device);
+	                          const std::string& device,
+	                          const float        sample_rate = 0);
 	State get_matching_state (const std::string& backend,
 	                          const std::string& driver,
 	                          const std::string& input_device,
-	                          const std::string& output_device);
+	                          const std::string& output_device,
+	                          const float        sample_rate = 0);
 
 	State get_saved_state_for_currently_displayed_backend_and_device ();
 	void  maybe_display_saved_state ();