initHEADmain

1 files changed, 111 insertions, 0 deletions

diff --git a/mod/nullsink.c b/mod/nullsink.c
new file mode 100644
index 0000000..0cbd810
--- /dev/null
+++ b/mod/nullsink.c
@@ -0,0 +1,111 @@
+/*
+ * melisma - extensible and scriptable audio engine
+ * Copyright (C) 2026  Ludvig Gunne Lindström
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#include <string.h>
+#include <lua.h>
+#include <lauxlib.h>
+#include "melisma.h"
+#include "mutil.h"
+
+#define NULLSINK_TYPENAME "nullsink"
+
+static int l_init(lua_State *s)
+{
+	ml_node *node = ml_create_node(NULL,NULL);
+	ml_label_node(node,"nullsink");
+	ml_node *root = ml_get_root_node();
+
+	ml_channel *src = ml_add_output(node);
+	ml_channel *dst = ml_add_input(root);
+
+	ml_connect(src,dst);
+
+	*(void**) lua_newuserdata(s,sizeof(void*)) = node;
+	luaL_setmetatable(s,NULLSINK_TYPENAME);
+
+	return 1;
+}
+
+static int l_ref(lua_State *s)
+{
+	ml_node *node = *(void**) luaL_checkudata(s,1,NULLSINK_TYPENAME);
+	ml_channel *src = mutil_get_channel(s,2);
+	ml_channel *dst = ml_add_input(node);
+	ml_connect(src,dst);
+	*(void**) lua_newuserdata(s,sizeof(void*)) = node;
+	luaL_setmetatable(s,NULLSINK_TYPENAME);
+	return 1;
+}
+
+int luaopen_melisma_nullsink(lua_State *s)
+{
+	ml_check_version();
+
+/*** Reference otherwise disconnected nodes.
+
+	local mnullsink = require 'melisma.nullsink'
+	local minterp = require 'melisma.interp'
+	local mevent = require 'melisma.event'
+
+	local interp = minterp.init(0)
+	interp:linear(1,60)
+
+	-- The output of interp is disconnected.
+	-- Need to connect it to a nullsink so we
+	-- can sample it in the event callback below.
+	local nullsink = mnullsink.init()
+	nullsink:ref(interp)
+
+	mevent.schedule(30, function()
+		print('current value:', interp:sample())
+	end)
+
+@classmod nullsink
+*/
+	lua_newtable(s);
+	int tbl = lua_gettop(s);
+
+/*** Create a nullsink.
+@static
+@function init
+@treturn nullsink The newly created nullsink.
+*/
+	lua_pushcfunction(s,l_init);
+	lua_setfield(s,tbl,"init");
+
+/*** Connect an input signal.
+
+This makes sure the input signal is processed
+even if it's not connected to anything else.
+
+@function ref
+@tparam channel input Input signal.
+@treturn nullsink
+*/
+	lua_pushcfunction(s,l_ref);
+	lua_setfield(s,tbl,"ref");
+
+	luaL_newmetatable(s,NULLSINK_TYPENAME);
+	int mt = lua_gettop(s);
+
+	lua_pushvalue(s,tbl);
+	lua_setfield(s,mt,"__index");
+
+	lua_settop(s,tbl);
+	return 1;
+}