From c21a0760a48ebd1d014d7ca66366477715cbb4a5 Mon Sep 17 00:00:00 2001
From: Robin Gareus <robin@gareus.org>
Date: Fri, 14 Oct 2016 15:06:49 +0200
Subject: [PATCH] allow feedback (loops) from internal sends

This facilitates custom "Echo" chains:

  Bus 1 [FX] [aux-send to Bus 2] -> master
  Bus 2 [FX] -> Bus 2
---
 libs/ardour/ardour/internal_send.h |  4 ++++
 libs/ardour/internal_send.cc       | 18 +++++++++++++++++-
 2 files changed, 21 insertions(+), 1 deletion(-)

diff --git a/libs/ardour/ardour/internal_send.h b/libs/ardour/ardour/internal_send.h
index 263c40b90b..8a85fc0f68 100644
--- a/libs/ardour/ardour/internal_send.h
+++ b/libs/ardour/ardour/internal_send.h
@@ -54,6 +54,9 @@ class LIBARDOUR_API InternalSend : public Send
 		return mixbufs;
 	}
 
+	bool allow_feedback () const { return _allow_feedback;}
+	void set_allow_feedback (bool yn);
+
 	void set_can_pan (bool yn);
 	uint32_t pan_outs () const;
 
@@ -63,6 +66,7 @@ class LIBARDOUR_API InternalSend : public Send
 	BufferSet mixbufs;
 	boost::shared_ptr<Route> _send_from;
 	boost::shared_ptr<Route> _send_to;
+	bool _allow_feedback;
 	PBD::ID _send_to_id;
 	PBD::ScopedConnection connect_c;
 	PBD::ScopedConnection source_connection;
diff --git a/libs/ardour/internal_send.cc b/libs/ardour/internal_send.cc
index 1746b00847..241506bdea 100644
--- a/libs/ardour/internal_send.cc
+++ b/libs/ardour/internal_send.cc
@@ -49,6 +49,7 @@ InternalSend::InternalSend (Session& s,
 		bool ignore_bitslot)
 	: Send (s, p, mm, role, ignore_bitslot)
 	, _send_from (sendfrom)
+	, _allow_feedback (false)
 {
 	if (sendto) {
 		if (use_target (sendto)) {
@@ -266,10 +267,20 @@ InternalSend::set_block_size (pframes_t nframes)
         return 0;
 }
 
+void
+InternalSend::set_allow_feedback (bool yn)
+{
+	_allow_feedback = yn;
+	_send_from->processors_changed (RouteProcessorChange ()); /* EMIT SIGNAL */
+}
+
 bool
 InternalSend::feeds (boost::shared_ptr<Route> other) const
 {
-	return _send_to == other;
+	if (_role == Listen || !_allow_feedback) {
+		return _send_to == other;
+	}
+	return false;
 }
 
 XMLNode&
@@ -284,6 +295,7 @@ InternalSend::state (bool full)
 	if (_send_to) {
 		node.add_property ("target", _send_to->id().to_s());
 	}
+	node.add_property ("allow-feedback", _allow_feedback);
 
 	return node;
 }
@@ -319,6 +331,10 @@ InternalSend::set_state (const XMLNode& node, int version)
 		}
 	}
 
+	if ((prop = node.property (X_("allow-feedback"))) != 0) {
+		_allow_feedback = string_is_affirmative (prop->value());
+	}
+
 	return 0;
 }