Mozzi  alpha 0.01.1t
sound synthesis library for Arduino
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Portamento.h
00001 /*
00002  * Portamento.h
00003  *
00004  * Copyright 2012 Tim Barrass.
00005  *
00006  * This file is part of Mozzi.
00007  *
00008  * Mozzi is free software: you can redistribute it and/or modify
00009  * it under the terms of the GNU General Public License as published by
00010  * the Free Software Foundation, either version 3 of the License, or
00011  * (at your option) any later version.
00012  *
00013  * Mozzi is distributed in the hope that it will be useful,
00014  * but WITHOUT ANY WARRANTY; without even the implied warranty of
00015  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
00016  * GNU General Public License for more details.
00017  *
00018  * You should have received a copy of the GNU General Public License
00019  * along with Mozzi.  If not, see <http://www.gnu.org/licenses/>.
00020  *
00021  */
00022 
00023 #ifndef PORTAMENTO_H_
00024 #define PORTAMENTO_H_
00025 
00026 #include "mozzi_midi.h"
00027 #include "fixedMath.h"
00028 #include "Line.h"
00029 
00032 template <unsigned int CONTROL_UPDATE_RATE>
00033 class
00034                 Portamento {
00035                 
00036 public:
00037 
00040                 Portamento():
00041                                                 MICROS_PER_CONTROL_STEP(1000000/CONTROL_UPDATE_RATE)
00042                 {
00043                 }
00044                 
00048                 inline
00049                 void setTime(unsigned int milliseconds){
00050                                 //control_steps_per_portamento = ((long)milliseconds*1000)/MICROS_PER_CONTROL_STEP; // more accurate but slower
00051                                 control_steps_per_portamento = convertMsecToControlSteps(milliseconds);
00052                 }
00053 
00057                 inline
00058                 void start(unsigned char note) {
00059                                 target_freq = Q16n16_mtof(Q8n0_to_Q16n16(note));
00060                                 aPortamentoLine.set(target_freq, control_steps_per_portamento);
00061                                 countdown = control_steps_per_portamento;
00062                                 portamento_on=true;
00063                 }
00064                 
00068                 inline
00069                 void start(Q16n16 note) {
00070                                 target_freq = Q16n16_mtof(note);
00071                                 aPortamentoLine.set(target_freq, control_steps_per_portamento);
00072                                 countdown = control_steps_per_portamento;
00073                                 portamento_on=true;
00074                 }
00075                 
00076 
00081                 inline
00082                 Q16n16 next() {
00083                                 if (portamento_on==true){
00084                                                 if(--countdown < 0) {
00085                                                                 // stay level when portamento has finished
00086                                                                 aPortamentoLine.set(target_freq, target_freq, control_steps_per_portamento);
00087                                                                 portamento_on=false;
00088                                                 }
00089                                 }
00090                                 return aPortamentoLine.next();
00091                 }
00092                 
00093                 private:
00094 
00095                 int countdown;
00096                 int control_steps_per_portamento;
00097                 Q16n16 target_freq;
00098                 bool portamento_on;
00099                 const unsigned int MICROS_PER_CONTROL_STEP;
00100                 Line <Q16n16> aPortamentoLine;
00101 
00102                 
00103                 // copied from ADSR.h
00104                 inline
00105                 static const unsigned int convertMsecToControlSteps(unsigned int msec){
00106                                 return (uint) (((ulong)msec*CONTROL_UPDATE_RATE)>>10); // approximate /1000 with shift
00107                 }
00108 
00109 };
00110 
00111 #endif /* PORTAMENTO_H_ */