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

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Revision 719 - (hide annotations) (download) (as text)
Sun Jul 24 16:48:11 2005 UTC (18 years, 8 months ago) by senkov
File MIME type: text/x-c++hdr
File size: 5782 byte(s)
Adjusted code to build on gcc (GCC) 3.4.3-20050110

1 schoenebeck 717 /***************************************************************************
2     * *
3     * Copyright (C) 2005 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 update(const uint16_t& ExtControlValue) {
66     const unsigned int intLimit = (unsigned int) -1; // all 0xFFFF...
67 senkov 719 const float max = this->InternalDepth + ExtControlValue * this->ExtControlDepthCoeff;
68 schoenebeck 717 if (RANGE == range_unsigned) {
69 schoenebeck 718 normalizer = max / (float) intLimit;
70 schoenebeck 717 } else { // signed range
71 schoenebeck 718 normalizer = max / (float) intLimit * 4.0f;
72 schoenebeck 717 offset = -max;
73     }
74     }
75    
76     /**
77     * Will be called by the voice when the key / voice was triggered.
78     *
79     * @param Frequency - frequency of the oscillator in Hz
80     * @param StartLevel - on which level the wave should start
81     * @param InternalDepth - firm, internal oscillator amplitude
82     * @param ExtControlDepth - defines how strong the external MIDI
83     * controller has influence on the
84     * oscillator amplitude
85 schoenebeck 718 * @param FlipPhase - inverts the oscillator wave against
86     * a horizontal axis
87 schoenebeck 717 * @param SampleRate - current sample rate of the engines
88     * audio output signal
89     */
90     void trigger(float Frequency, start_level_t StartLevel, uint16_t InternalDepth, uint16_t ExtControlDepth, bool FlipPhase, unsigned int SampleRate) {
91 senkov 719 this->InternalDepth = (InternalDepth / 1200.0f) * this->Max;
92     this->ExtControlDepthCoeff = (((float) ExtControlDepth / 1200.0f) / 127.0f) * this->Max;
93 schoenebeck 718 if (RANGE == range_unsigned) {
94     this->InternalDepth *= 2.0f;
95     this->ExtControlDepthCoeff *= 2.0f;
96     }
97 schoenebeck 717
98     const unsigned int intLimit = (unsigned int) -1; // all 0xFFFF...
99     const float r = Frequency / (float) SampleRate; // frequency alteration quotient
100     c = (int) (intLimit * r);
101    
102     switch (StartLevel) {
103 schoenebeck 718 case start_level_max:
104     iLevel = (FlipPhase) ? 0 : intLimit >> 1;
105 schoenebeck 717 break;
106 schoenebeck 718 case start_level_mid:
107 schoenebeck 717 if (FlipPhase) c = -c; // wave should go down
108 schoenebeck 718 iLevel = intLimit >> 2;
109 schoenebeck 717 break;
110 schoenebeck 718 case start_level_min:
111     iLevel = (FlipPhase) ? intLimit >> 1 : 0;
112 schoenebeck 717 break;
113     }
114     }
115    
116     private:
117     int iLevel;
118     int c;
119     float offset; ///< only needed for signed range
120     float normalizer;
121     };
122    
123     } // namespace LinuxSampler
124    
125     #endif // __LS_LFOTRIANGLEINTMATH_H__

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