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/*
* 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;
}
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