From 183604a66b75611dee7aa1d75ecae0bb0d7c2e4d Mon Sep 17 00:00:00 2001
From: Robin Gareus <robin@gareus.org>
Date: Sun, 4 Sep 2022 00:43:00 +0200
Subject: [PATCH] Add polarity invert switch to sends

This allows to invert polarity of the signals of all channels on the
send path. There is intentionally no per channel control.

see https://discourse.ardour.org/t/send-phase-swtich/107564
---
 libs/ardour/ardour/delivery.h |  1 +
 libs/ardour/delivery.cc       | 23 +++++++++++++++++++++++
 libs/ardour/internal_send.cc  |  2 ++
 libs/ardour/send.cc           | 34 +++++++++++++++++++++++++++++++---
 4 files changed, 57 insertions(+), 3 deletions(-)

diff --git a/libs/ardour/ardour/delivery.h b/libs/ardour/ardour/delivery.h
index cc3b6321c3..72c443d4c5 100644
--- a/libs/ardour/ardour/delivery.h
+++ b/libs/ardour/ardour/delivery.h
@@ -120,6 +120,7 @@ protected:
 	BufferSet*  _output_buffers;
 	gain_t      _current_gain;
 	boost::shared_ptr<PannerShell> _panshell;
+	boost::shared_ptr<AutomationControl> _polarity_control;
 
 	gain_t target_gain ();
 
diff --git a/libs/ardour/delivery.cc b/libs/ardour/delivery.cc
index ff0c22ff08..09a19e49f4 100644
--- a/libs/ardour/delivery.cc
+++ b/libs/ardour/delivery.cc
@@ -376,6 +376,9 @@ Delivery::state () const
 			node.add_child_nocopy (_panshell->unlinked_pannable()->get_state ());
 		}
 	}
+	if (_polarity_control) {
+		node.add_child_nocopy (_polarity_control->get_state());
+	}
 
 	return node;
 }
@@ -407,6 +410,22 @@ Delivery::set_state (const XMLNode& node, int version)
 		_panshell->unlinked_pannable()->set_state (*pannnode, version);
 	}
 
+	if (_polarity_control) {
+		for (auto const& i : node.children()) {
+			if (i->name() != Controllable::xml_node_name) {
+				continue;
+			}
+			std::string control_name;
+			if (!i->get_property (X_("name"), control_name)) {
+				continue;
+			}
+			if (control_name == "polarity-invert") {
+				_polarity_control->set_state (*i, version);
+				break;
+			}
+		}
+	}
+
 	return 0;
 }
 
@@ -583,6 +602,10 @@ Delivery::target_gain ()
 		desired_gain = GAIN_COEFF_ZERO;
 	}
 
+	if (_polarity_control && _polarity_control->get_value () > 0) {
+		desired_gain *= -1;
+	}
+
 	return desired_gain;
 }
 
diff --git a/libs/ardour/internal_send.cc b/libs/ardour/internal_send.cc
index 86806047f7..923462c35c 100644
--- a/libs/ardour/internal_send.cc
+++ b/libs/ardour/internal_send.cc
@@ -211,6 +211,8 @@ InternalSend::send_to_going_away ()
 void
 InternalSend::run (BufferSet& bufs, samplepos_t start_sample, samplepos_t end_sample, double speed, pframes_t nframes, bool)
 {
+	automation_run (start_sample, nframes);
+
 	if (!check_active() || !_send_to) {
 		_meter->reset ();
 		return;
diff --git a/libs/ardour/send.cc b/libs/ardour/send.cc
index ba0be0259e..f183cd98a3 100644
--- a/libs/ardour/send.cc
+++ b/libs/ardour/send.cc
@@ -108,6 +108,15 @@ Send::Send (Session& s, boost::shared_ptr<Pannable> p, boost::shared_ptr<MuteMas
 	_send_delay.reset (new DelayLine (_session, "Send-" + name()));
 	_thru_delay.reset (new DelayLine (_session, "Thru-" + name()));
 
+
+	if (_role == Delivery::Aux || _role == Delivery::Send) {
+		_polarity_control = boost::shared_ptr<AutomationControl> (new AutomationControl (_session, PhaseAutomation, ParameterDescriptor (PhaseAutomation),
+		                                                                                 boost::shared_ptr<AutomationList>(new AutomationList(Evoral::Parameter(PhaseAutomation), time_domain())),
+		                                                                                 "polarity-invert"));
+		//_polarity_control->set_flag (Controllable::InlineControl);
+		add_control (_polarity_control);
+	}
+
 	if (panner_shell()) {
 		panner_shell()->Changed.connect_same_thread (*this, boost::bind (&Send::panshell_changed, this));
 		panner_shell()->PannableChanged.connect_same_thread (*this, boost::bind (&Send::pannable_changed, this));
@@ -227,6 +236,8 @@ Send::set_delay_out (samplecnt_t delay, size_t /*bus*/)
 void
 Send::run (BufferSet& bufs, samplepos_t start_sample, samplepos_t end_sample, double speed, pframes_t nframes, bool)
 {
+	automation_run (start_sample, nframes);
+
 	if (_output->n_ports() == ChanCount::ZERO) {
 		_meter->reset ();
 		_active = _pending_active;
@@ -298,10 +309,26 @@ Send::set_state (const XMLNode& node, int version)
 		return set_state_2X (node, version);
 	}
 
-	XMLNode* gain_node;
+	for (auto const& i : node.children()) {
+		if (i->name() != Controllable::xml_node_name) {
+			continue;
+		}
+		if (version < 7000) {
+			/* old versions had a single Controllable only, and it was
+			 * not always a "gaincontrol"
+			 */
+			_gain_control->set_state (*i, version);
+			break;
+		}
 
-	if ((gain_node = node.child (Controllable::xml_node_name.c_str ())) != 0) {
-		_gain_control->set_state (*gain_node, version);
+		std::string control_name;
+		if (!i->get_property (X_("name"), control_name)) {
+			continue;
+		}
+		if (control_name == "gaincontrol" /* gain_control_name (BusSendLevel) */) {
+			_gain_control->set_state (*i, version);
+			break;
+		}
 	}
 
 	if (version <= 6000) {
@@ -317,6 +344,7 @@ Send::set_state (const XMLNode& node, int version)
 		{
 			XMLNode* processor = node.child ("Processor");
 			if (processor) {
+				XMLNode* gain_node;
 				nn = processor;
 				if ((gain_node = nn->child (Controllable::xml_node_name.c_str ())) != 0) {
 					_gain_control->set_state (*gain_node, version);