add a convenient lua forward mapped buffers method

libs/ardour/ardour/dsp_filter.h

@@ -25,7 +25,11 @@
 #include <glib.h>
 #include <glibmm.h>
 #include <fftw3.h>
+
+#include "ardour/buffer_set.h"
+#include "ardour/chan_mapping.h"
 #include "ardour/libardour_visibility.h"
+#include "ardour/types.h"
 
 namespace ARDOUR { namespace DSP {
 
@@ -159,6 +163,12 @@ namespace ARDOUR { namespace DSP {
 	 */
 	float log_meter_coeff (float coeff);
 
+	void process_map (BufferSet* bufs,
+	                  const ChanMapping& in,
+	                  const ChanMapping& out,
+	                  pframes_t nframes, framecnt_t offset,
+	                  const DataType&);
+
 	/** 1st order Low Pass filter */
 	class LIBARDOUR_API LowPass {
 		public:

libs/ardour/dsp_filter.cc

@@ -21,6 +21,7 @@
 #include <stdlib.h>
 #include <cmath>
 #include "ardour/dB.h"
+#include "ardour/buffer.h"
 #include "ardour/dsp_filter.h"
 
 #ifdef COMPILER_MSVC
@@ -73,6 +74,35 @@ ARDOUR::DSP::peaks (float *data, float &min, float &max, uint32_t n_samples) {
 	}
 }
 
+void
+ARDOUR::DSP::process_map (BufferSet* bufs, const ChanMapping& in, const ChanMapping& out, pframes_t nframes, framecnt_t offset, const DataType& dt)
+{
+	const ChanMapping::Mappings& im (in.mappings());
+	const ChanMapping::Mappings& om (out.mappings());
+
+	for (ChanMapping::Mappings::const_iterator tm = im.begin(); tm != im.end(); ++tm) {
+		if (tm->first != dt) { continue; }
+		for (ChanMapping::TypeMapping::const_iterator i = tm->second.begin(); i != tm->second.end(); ++i) {
+			bool valid;
+			const uint32_t idx = out.get (dt, i->second, &valid);
+			if (valid && idx != i->first) {
+				bufs->get (dt, idx).read_from (bufs->get (dt, i->first), nframes, offset, offset);
+			}
+		}
+	}
+	for (ChanMapping::Mappings::const_iterator tm = im.begin(); tm != im.end(); ++tm) {
+		if (tm->first != dt) { continue; }
+		for (ChanMapping::TypeMapping::const_iterator i = tm->second.begin(); i != tm->second.end(); ++i) {
+			bool valid;
+			in.get_src (dt, i->first, &valid);
+			if (!valid) {
+				bufs->get (dt, i->second).silence (nframes, offset);
+			}
+		}
+	}
+
+}
+
 LowPass::LowPass (double samplerate, float freq)
 	: _rate (samplerate)
 	, _z (0)

libs/ardour/luabindings.cc

@@ -1343,6 +1343,7 @@ LuaBindings::dsp (lua_State* L)
 		.addFunction ("mmult", &DSP::mmult)
 		.addFunction ("log_meter", &DSP::log_meter)
 		.addFunction ("log_meter_coeff", &DSP::log_meter_coeff)
+		.addFunction ("process_map", &DSP::process_map)
 		.addRefFunction ("peaks", &DSP::peaks)
 
 		.beginClass <DSP::LowPass> ("LowPass")

scripts/rawmidi.lua

@@ -46,8 +46,24 @@ function dsp_runmap (bufs, in_map, out_map, n_samples, offset)
 	-- The following code is needed with "dsp_runmap" to work for arbitrary pin connections
 	-- this passes though all audio/midi data unprocessed.
 
-	local audio_ins = in_map:count (): n_audio () -- number of audio input buffers
-	local audio_outs = out_map:count (): n_audio () -- number of audio output buffers
+	ARDOUR.DSP.process_map (bufs, in_map, out_map, n_samples, offset, ARDOUR.DataType ("audio"))
+	ARDOUR.DSP.process_map (bufs, in_map, out_map, n_samples, offset, ARDOUR.DataType ("midi"))
+
+	-- equivalent lua code.
+	-- NOTE: the lua implementation below is intended for io-config [-1,-1].
+	-- It only works for actually mapped channels due to in_map:count() out_map:count()
+	-- being identical to the i/o pin count in this case.
+	--
+	-- Plugins that have multiple possible configurations will need to implement
+	-- dsp_configure() and remember the actual channel count.
+	--
+	-- ARDOUR.DSP.process_map() does iterate over the mapping itself and works generally.
+	-- Still the lua code below does lend itself as elaborate example.
+	--
+	--[[
+
+	local audio_ins = in_map:count (): n_audio () -- number of mapped audio input buffers
+	local audio_outs = out_map:count (): n_audio () -- number of mapped audio output buffers
 	assert (audio_outs, audio_ins) -- ioconfig [-1, -1]: must match
 
 	-- copy audio data if any
@@ -94,4 +110,5 @@ function dsp_runmap (bufs, in_map, out_map, n_samples, offset)
 			bufs:get_midi (ob):silence (n_samples, offset)
 		end
 	end
+	--]]
 end