norns amplitude poll test

amp_poll_test.lua

--- amp poll test  
engine.name="AmpPollTest"
handle_amp_poll = function(channel, value)
    local db
    if value <= 0.0 then db = "-inf" 
    else db = 20 * math.log10(value)
    end
    print("amp poll: "..channel.." = "..db)
end

init = function() 
    print("amp_poll_test init")

    params:add({
        type='control',
        id='amp',
        name='amp',
        controlspec=controlspec.new(0, 1, 'lin', 0, 0.001, ''),
        action=function(value) engine.amp(value) end
    })

    params:add({
        type='number',
        id='which',
        name='which',
        minval=1, 
        maxval=2,
        default=0,
        action=function(value)
            -- zero-base for supercollider
            engine.which(value-1)
        end
    })
    
    local p = poll.set("amp_out_l", function(x) handle_amp_poll(1, x) end)
    p:start()

    p = poll.set("amp_out_r", function(x) handle_amp_poll(2, x) end)
    p:start()

end

Engine_AmpPollTest.sc

Engine_AmpPollTest : CroneEngine {
    var <synth;

	*new { arg context, doneCallback;
		^super.new(context, doneCallback);
	}

	alloc {
        synth = SynthDef.new(\amp_poll_test, {
            arg out=0, amp=0.125, which = 0;
            var sources = [
                WhiteNoise.ar,
                SinOsc.ar(220)
            ];
            var signal = (Select.ar(which, sources) * amp).dup;
            Out.ar(out, signal.dup(2));
        }).play(target: context.xg);

        this.addCommand("amp", "f", { 
            arg msg;
            var amp = msg[1];
            synth.set(\amp, amp.clip(0, 1));
        });

        this.addCommand("which", "i", { 
            arg msg;
            var which = msg[1];
            synth.set(\which, which.clip(0, 1));
        });
    }

    free {
        synth.free;
    }
}