From c6955d4994e7b699e69227b17d8b74aefe0f5028 Mon Sep 17 00:00:00 2001
From: Robin Gareus <robin@gareus.org>
Date: Fri, 19 Oct 2018 18:10:19 +0200
Subject: [PATCH] Allow Lua DSP processors to report latency

---
 libs/ardour/ardour/luaproc.h |  6 +++++-
 libs/ardour/luaproc.cc       | 15 +++++++++++++++
 2 files changed, 20 insertions(+), 1 deletion(-)

diff --git a/libs/ardour/ardour/luaproc.h b/libs/ardour/ardour/luaproc.h
index 8ac27095ab..45b730ff73 100644
--- a/libs/ardour/ardour/luaproc.h
+++ b/libs/ardour/ardour/luaproc.h
@@ -85,7 +85,7 @@ public:
 	void cleanup () { }
 
 	int set_block_size (pframes_t /*nframes*/) { return 0; }
-	samplecnt_t  signal_latency() const { return 0; }
+	samplecnt_t signal_latency() const { return _signal_latency; }
 
 	int connect_and_run (BufferSet& bufs,
 			samplepos_t start, samplepos_t end, double speed,
@@ -148,6 +148,7 @@ private:
 #endif
 	LuaState lua;
 	luabridge::LuaRef * _lua_dsp;
+	luabridge::LuaRef * _lua_latency;
 	std::string _script;
 	std::string _origin;
 	std::string _docs;
@@ -176,6 +177,8 @@ private:
 	std::map<int, std::string> _param_doc;
 	uint32_t _designated_bypass_port;
 
+	samplecnt_t _signal_latency;
+
 	float* _control_data;
 	float* _shadow_data;
 
@@ -192,6 +195,7 @@ private:
 	bool _has_midi_input;
 	bool _has_midi_output;
 
+
 #ifdef WITH_LUAPROC_STATS
 	int64_t _stats_avg[2];
 	int64_t _stats_max[2];
diff --git a/libs/ardour/luaproc.cc b/libs/ardour/luaproc.cc
index 4e2b32c838..ec13efb1bf 100644
--- a/libs/ardour/luaproc.cc
+++ b/libs/ardour/luaproc.cc
@@ -54,10 +54,12 @@ LuaProc::LuaProc (AudioEngine& engine,
 	, lua (lua_newstate (&PBD::ReallocPool::lalloc, &_mempool))
 #endif
 	, _lua_dsp (0)
+	, _lua_latency (0)
 	, _script (script)
 	, _lua_does_channelmapping (false)
 	, _lua_has_inline_display (false)
 	, _designated_bypass_port (UINT32_MAX)
+	, _signal_latency (0)
 	, _control_data (0)
 	, _shadow_data (0)
 	, _configured (false)
@@ -85,11 +87,13 @@ LuaProc::LuaProc (const LuaProc &other)
 	, lua (lua_newstate (&PBD::ReallocPool::lalloc, &_mempool))
 #endif
 	, _lua_dsp (0)
+	, _lua_latency (0)
 	, _script (other.script ())
 	, _origin (other._origin)
 	, _lua_does_channelmapping (false)
 	, _lua_has_inline_display (false)
 	, _designated_bypass_port (UINT32_MAX)
+	, _signal_latency (0)
 	, _control_data (0)
 	, _shadow_data (0)
 	, _configured (false)
@@ -125,6 +129,7 @@ LuaProc::~LuaProc () {
 #endif
 	lua.do_command ("collectgarbage();");
 	delete (_lua_dsp);
+	delete (_lua_latency);
 	delete [] _control_data;
 	delete [] _shadow_data;
 }
@@ -236,6 +241,11 @@ LuaProc::load_script ()
 		assert (0);
 	}
 
+	luabridge::LuaRef lua_dsp_latency = luabridge::getGlobal (L, "dsp_latency");
+	if (lua_dsp_latency.type () == LUA_TFUNCTION) {
+		_lua_latency = new luabridge::LuaRef (lua_dsp_latency);
+	}
+
 	// initialize the DSP if needed
 	luabridge::LuaRef lua_dsp_init = luabridge::getGlobal (L, "dsp_init");
 	if (lua_dsp_init.type () == LUA_TFUNCTION) {
@@ -735,6 +745,11 @@ LuaProc::connect_and_run (BufferSet& bufs,
 				}
 			}
 		}
+
+		if (_lua_latency) {
+			_signal_latency = (*_lua_latency)();
+		}
+
 	} catch (luabridge::LuaException const& e) {
 		PBD::error << "LuaException: " << e.what () << "\n";
 #ifndef NDEBUG