/[svn]/linuxsampler/trunk/src/engines/common/LFOTriangleIntMath.h
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Contents of /linuxsampler/trunk/src/engines/common/LFOTriangleIntMath.h

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Revision 3118 - (show annotations) (download) (as text)
Fri Apr 21 13:33:03 2017 UTC (4 weeks, 3 days ago) by schoenebeck
File MIME type: text/x-c++hdr
File size: 7529 byte(s)
* NKSP: Fixed crash when using built-in script array variable "%ALL_EVENTS".
* NKSP: Added built-in function "change_amp_lfo_depth()".
* NKSP: Added built-in function "change_amp_lfo_freq()".
* NKSP: Added built-in function "change_pitch_lfo_depth()".
* NKSP: Added built-in function "change_pitch_lfo_freq()".
* Bumped version (2.0.0.svn44).

1 /***************************************************************************
2 * *
3 * Copyright (C) 2005 - 2017 Christian Schoenebeck *
4 * *
5 * This library is free software; you can redistribute it and/or modify *
6 * it under the terms of the GNU General Public License as published by *
7 * the Free Software Foundation; either version 2 of the License, or *
8 * (at your option) any later version. *
9 * *
10 * This library is distributed in the hope that it will be useful, *
11 * but WITHOUT ANY WARRANTY; without even the implied warranty of *
12 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the *
13 * GNU General Public License for more details. *
14 * *
15 * You should have received a copy of the GNU General Public License *
16 * along with this library; if not, write to the Free Software *
17 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, *
18 * MA 02111-1307 USA *
19 ***************************************************************************/
20
21 #ifndef __LS_LFOTRIANGLEINTMATH_H__
22 #define __LS_LFOTRIANGLEINTMATH_H__
23
24 #include "LFOBase.h"
25
26 namespace LinuxSampler {
27
28 /** @brief Triangle LFO (int math implementation)
29 *
30 * This is a triangle Low Frequency Oscillator which uses pure integer
31 * math (without branches) to synthesize the triangular wave.
32 */
33 template<range_type_t RANGE>
34 class LFOTriangleIntMath : public LFOBase<RANGE> {
35 public:
36
37 /**
38 * Constructor
39 *
40 * @param Max - maximum value of the output levels
41 */
42 LFOTriangleIntMath(float Max) : LFOBase<RANGE>::LFOBase(Max) {
43 }
44
45 /**
46 * Calculates exactly one sample point of the LFO wave.
47 *
48 * @returns next LFO level
49 */
50 inline float render() {
51 const int signshifts = (sizeof(int) * 8) - 1;
52 iLevel += c;
53 const int iSign = (iLevel >> signshifts) | 1;
54 if (RANGE == range_unsigned)
55 return normalizer * (float) (iSign * iLevel);
56 else /* signed range */
57 return normalizer * (float) (iSign * iLevel) + offset;
58 }
59
60 /**
61 * Update LFO depth with a new external controller value.
62 *
63 * @param ExtControlValue - new external controller value
64 */
65 inline void updateByMIDICtrlValue(const uint16_t& ExtControlValue) {
66 this->ExtControlValue = ExtControlValue;
67
68 const unsigned int intLimit = (unsigned int) -1; // all 0xFFFF...
69 const float max = (this->InternalDepth + ExtControlValue * this->ExtControlDepthCoeff) * this->ScriptDepthFactor;
70 if (RANGE == range_unsigned) {
71 normalizer = max / (float) intLimit;
72 } else { // signed range
73 normalizer = max / (float) intLimit * 4.0f;
74 offset = -max;
75 }
76 }
77
78 /**
79 * Will be called by the voice when the key / voice was triggered.
80 *
81 * @param Frequency - frequency of the oscillator in Hz
82 * @param StartLevel - on which level the wave should start
83 * @param InternalDepth - firm, internal oscillator amplitude
84 * @param ExtControlDepth - defines how strong the external MIDI
85 * controller has influence on the
86 * oscillator amplitude
87 * @param FlipPhase - inverts the oscillator wave against
88 * a horizontal axis
89 * @param SampleRate - current sample rate of the engines
90 * audio output signal
91 */
92 void trigger(float Frequency, start_level_t StartLevel, uint16_t InternalDepth, uint16_t ExtControlDepth, bool FlipPhase, unsigned int SampleRate) {
93 this->Frequency = Frequency;
94 this->InternalDepth = (InternalDepth / 1200.0f) * this->Max;
95 this->ExtControlDepthCoeff = (((float) ExtControlDepth / 1200.0f) / 127.0f) * this->Max;
96 this->ScriptFrequencyFactor = this->ScriptDepthFactor = 1.f; // reset for new voice
97 if (RANGE == range_unsigned) {
98 this->InternalDepth *= 2.0f;
99 this->ExtControlDepthCoeff *= 2.0f;
100 }
101
102 const unsigned int intLimit = (unsigned int) -1; // all 0xFFFF...
103 const float freq = Frequency * this->ScriptFrequencyFactor;
104 const float r = freq / (float) SampleRate; // frequency alteration quotient
105 c = (int) (intLimit * r);
106
107 switch (StartLevel) {
108 case start_level_max:
109 iLevel = (FlipPhase) ? 0 : intLimit >> 1;
110 break;
111 case start_level_mid:
112 if (FlipPhase) c = -c; // wave should go down
113 iLevel = intLimit >> 2;
114 break;
115 case start_level_min:
116 iLevel = (FlipPhase) ? intLimit >> 1 : 0;
117 break;
118 }
119 }
120
121 /**
122 * Should be invoked after the LFO is triggered.
123 * @param phase From 0 to 360 degrees.
124 */
125 void setPhase(float phase) {
126 if (phase < 0) phase = 0;
127 if (phase > 360) phase = 360;
128 phase /= 360.0f;
129 const unsigned int intLimit = (unsigned int) -1; // all 0xFFFF...
130 unsigned int uiPhase = intLimit * phase + iLevel;
131 if (uiPhase > intLimit / 2) iLevel = uiPhase - intLimit;
132 else iLevel = uiPhase;
133 }
134
135 void setFrequency(float Frequency, unsigned int SampleRate) {
136 this->Frequency = Frequency;
137 const float freq = Frequency * this->ScriptFrequencyFactor;
138 const unsigned int intLimit = (unsigned int) -1; // all 0xFFFF...
139 float r = freq / (float) SampleRate; // frequency alteration quotient
140 c = (int) (intLimit * r);
141 }
142
143 void setScriptDepthFactor(float factor) {
144 this->ScriptDepthFactor = factor;
145 updateByMIDICtrlValue(this->ExtControlValue);
146 }
147
148 void setScriptFrequencyFactor(float factor, unsigned int SampleRate) {
149 this->ScriptFrequencyFactor = factor;
150 setFrequency(this->Frequency, SampleRate);
151 }
152
153 protected:
154 int iLevel;
155 int c;
156 float offset; ///< only needed for signed range
157 float normalizer;
158 };
159
160 } // namespace LinuxSampler
161
162 #endif // __LS_LFOTRIANGLEINTMATH_H__

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