[LAD] LV2::Synth from one note to another

Hello I managed to make my example plugin <https://bitbucket.org/xaccrocheur/ksi> (based on the only LV2 synth tutorial <http://www.nongnu.org/ll-plugins/lv2pftci/#A_synth> that I could find) monophonic :) Now the only think that is left is a portamento function, to go from one note to another (/exactly/ like so-404 <http://d00m.org/%7Esomeone/so404/> does). I guess it has to do with the void on(unsigned char key, unsigned char velocity) { m_key = key; m_period = m_rate * 4.0 / LV2::key2hz(m_key); m_envelope = velocity / 128.0; } void off(unsigned char velocity) { m_key = LV2::INVALID_KEY; } functions, I need to store the "note out" value to go from that, to a "note in"... Does anyone know the algorithm to implement that? That would really help me. Thanks PS - Excuse my poor English, I'm working on it -- Philippe Coatmeur