From e974a861ead7d729b9eba465fed9350c89cab770 Mon Sep 17 00:00:00 2001
From: Robin Gareus <robin@gareus.org>
Date: Wed, 1 Oct 2025 22:52:07 +0200
Subject: [PATCH] LV2: add debug option to dump plugin/UI Atom communication

---
 libs/ardour/ardour/debug.h |  2 ++
 libs/ardour/debug.cc       |  2 ++
 libs/ardour/lv2_plugin.cc  | 40 ++++++++++++++++++++++++++++++++++++++
 3 files changed, 44 insertions(+)

diff --git a/libs/ardour/ardour/debug.h b/libs/ardour/ardour/debug.h
index c5e71d5c13..8d3e5a7f1c 100644
--- a/libs/ardour/ardour/debug.h
+++ b/libs/ardour/ardour/debug.h
@@ -61,6 +61,8 @@ namespace PBD {
 		LIBARDOUR_API extern DebugBits IOTaskList;
 		LIBARDOUR_API extern DebugBits LTC;
 		LIBARDOUR_API extern DebugBits LV2;
+		LIBARDOUR_API extern DebugBits LV2AtomToUI;
+		LIBARDOUR_API extern DebugBits LV2AtomFromUI;
 		LIBARDOUR_API extern DebugBits LV2Automate;
 		LIBARDOUR_API extern DebugBits LatencyCompensation;
 		LIBARDOUR_API extern DebugBits LatencyDelayLine;
diff --git a/libs/ardour/debug.cc b/libs/ardour/debug.cc
index b738c3f7b7..99ed4ff45f 100644
--- a/libs/ardour/debug.cc
+++ b/libs/ardour/debug.cc
@@ -57,6 +57,8 @@ PBD::DebugBits PBD::DEBUG::Graph = PBD::new_debug_bit ("graph");
 PBD::DebugBits PBD::DEBUG::IOTaskList = PBD::new_debug_bit ("iotasklist");
 PBD::DebugBits PBD::DEBUG::LTC = PBD::new_debug_bit ("ltc");
 PBD::DebugBits PBD::DEBUG::LV2 = PBD::new_debug_bit ("lv2");
+PBD::DebugBits PBD::DEBUG::LV2AtomToUI = PBD::new_debug_bit ("lv2atomtoui");
+PBD::DebugBits PBD::DEBUG::LV2AtomFromUI = PBD::new_debug_bit ("lv2atomfromui");
 PBD::DebugBits PBD::DEBUG::LV2Automate = PBD::new_debug_bit ("lv2automate");
 PBD::DebugBits PBD::DEBUG::LatencyCompensation = PBD::new_debug_bit ("latencycompensation");
 PBD::DebugBits PBD::DEBUG::LatencyDelayLine = PBD::new_debug_bit ("latencydelayline");
diff --git a/libs/ardour/lv2_plugin.cc b/libs/ardour/lv2_plugin.cc
index f488a708a8..94318f490c 100644
--- a/libs/ardour/lv2_plugin.cc
+++ b/libs/ardour/lv2_plugin.cc
@@ -119,6 +119,10 @@
 #include <suil/suil.h>
 #endif
 
+#ifdef HAVE_SRATOM
+#include <sratom/sratom.h>
+#endif
+
 // Compatibility for old LV2
 #ifndef LV2_ATOM_CONTENTS_CONST
 #define LV2_ATOM_CONTENTS_CONST(type, atom) \
@@ -1916,6 +1920,24 @@ LV2Plugin::write_from_ui(uint32_t       index,
 		return false;
 	}
 
+#ifdef HAVE_SRATOM
+	if (DEBUG_ENABLED (DEBUG::LV2AtomFromUI)) {
+		Sratom* sratom = sratom_new (_uri_map.urid_map());
+		const LV2_Atom* atom = (LV2_Atom const*)(body);
+		char* const str = sratom_to_turtle (sratom,
+				_uri_map.urid_unmap(),
+				"ardour:",
+				NULL,
+				NULL,
+				atom->type,
+				atom->size,
+				LV2_ATOM_BODY_CONST(atom));
+		DEBUG_TRACE (DEBUG::LV2AtomFromUI, string_compose ("Plugin[%1] <- UI: port %2 (%3 bytes)\n%4\n", name(), index, atom->size, str));
+		free (str);
+		sratom_free (sratom);
+	}
+#endif
+
 	Glib::Threads::Mutex::Lock lm (_slave_lock, Glib::Threads::TRY_LOCK);
 	if (lm.locked()) {
 		for (auto const& i : _slaves) {
@@ -3282,6 +3304,24 @@ LV2Plugin::connect_and_run(BufferSet& bufs,
 				}
 
 				if (!_to_ui) continue;
+
+#ifdef HAVE_SRATOM
+				if (DEBUG_ENABLED (DEBUG::LV2AtomToUI)) {
+					Sratom* sratom = sratom_new (_uri_map.urid_map());
+					LV2_Atom const* atom = (LV2_Atom*)(data - sizeof(LV2_Atom));
+					char* const str = sratom_to_turtle (sratom,
+							_uri_map.urid_unmap(),
+							"ardour:",
+							NULL,
+							NULL,
+							atom->type,
+							atom->size,
+							LV2_ATOM_BODY_CONST(atom));
+					DEBUG_TRACE (DEBUG::LV2AtomToUI, string_compose ("Plugin[%1] -> UI: port %2 (%3 bytes)\n%4\n", name(), port_index, atom->size, str));
+					free (str);
+					sratom_free (sratom);
+				}
+#endif
 				write_to_ui(port_index, URIMap::instance().urids.atom_eventTransfer,
 				            size + sizeof(LV2_Atom),
 				            data - sizeof(LV2_Atom));