1 /*
2  * Copyright (C) 2015 The Android Open Source Project
3  *
4  * Licensed under the Apache License, Version 2.0 (the "License");
5  * you may not use this file except in compliance with the License.
6  * You may obtain a copy of the License at
7  *
8  *      http://www.apache.org/licenses/LICENSE-2.0
9  *
10  * Unless required by applicable law or agreed to in writing, software
11  * distributed under the License is distributed on an "AS IS" BASIS,
12  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13  * See the License for the specific language governing permissions and
14  * limitations under the License.
15  */
16 
17 package com.example.android.common.midi.synth;
18 
19 public class SawOscillator extends SynthUnit {
20     private float mPhase = 0.0f;
21     private float mPhaseIncrement = 0.01f;
22     private float mFrequency = 0.0f;
23     private float mFrequencyScaler = 1.0f;
24     private float mAmplitude = 1.0f;
25 
setPitch(float pitch)26     public void setPitch(float pitch) {
27         float freq = (float) pitchToFrequency(pitch);
28         setFrequency(freq);
29     }
30 
setFrequency(float frequency)31     public void setFrequency(float frequency) {
32         mFrequency = frequency;
33         updatePhaseIncrement();
34     }
35 
updatePhaseIncrement()36     private void updatePhaseIncrement() {
37         mPhaseIncrement = 2.0f * mFrequency * mFrequencyScaler / 48000.0f;
38     }
39 
setAmplitude(float amplitude)40     public void setAmplitude(float amplitude) {
41         mAmplitude = amplitude;
42     }
43 
getAmplitude()44     public float getAmplitude() {
45         return mAmplitude;
46     }
47 
getFrequencyScaler()48     public float getFrequencyScaler() {
49         return mFrequencyScaler;
50     }
51 
setFrequencyScaler(float frequencyScaler)52     public void setFrequencyScaler(float frequencyScaler) {
53         mFrequencyScaler = frequencyScaler;
54         updatePhaseIncrement();
55     }
56 
incrementWrapPhase()57     float incrementWrapPhase() {
58         mPhase += mPhaseIncrement;
59         while (mPhase > 1.0) {
60             mPhase -= 2.0;
61         }
62         while (mPhase < -1.0) {
63             mPhase += 2.0;
64         }
65         return mPhase;
66     }
67 
68     @Override
render()69     public float render() {
70         return incrementWrapPhase() * mAmplitude;
71     }
72 
73 }
74