engines/common/LFOTriangleIntMath.h

/***************************************************************************
 *                                                                         *
 *   Copyright (C) 2005 Christian Schoenebeck                              *
 *                                                                         *
 *   This library is free software; you can redistribute it and/or modify  *
 *   it under the terms of the GNU General Public License as published by  *
 *   the Free Software Foundation; either version 2 of the License, or     *
 *   (at your option) any later version.                                   *
 *                                                                         *
 *   This library is distributed in the hope that it will be useful,       *
 *   but WITHOUT ANY WARRANTY; without even the implied warranty of        *
 *   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the         *
 *   GNU General Public License for more details.                          *
 *                                                                         *
 *   You should have received a copy of the GNU General Public License     *
 *   along with this library; if not, write to the Free Software           *
 *   Foundation, Inc., 59 Temple Place, Suite 330, Boston,                 *
 *   MA  02111-1307  USA                                                   *
 ***************************************************************************/

#ifndef __LS_LFOTRIANGLEINTMATH_H__
#define __LS_LFOTRIANGLEINTMATH_H__

#include "LFOBase.h"

namespace LinuxSampler {

    /** @brief Triangle LFO (int math implementation)
     *
     * This is a triangle Low Frequency Oscillator which uses pure integer
     * math (without branches) to synthesize the triangular wave.
     */
    template<range_type_t RANGE>
    class LFOTriangleIntMath : public LFOBase<RANGE> {
        public:

            /**
             * Constructor
             *
             * @param Max - maximum value of the output levels
             */
            LFOTriangleIntMath(float Max) : LFOBase<RANGE>::LFOBase(Max) {
            }

            /**
             * Calculates exactly one sample point of the LFO wave.
             *
             * @returns next LFO level
             */
            inline float render() {
                const int signshifts = (sizeof(int) * 8) - 1;
                iLevel += c;
                const int iSign  = (iLevel >> signshifts) | 1;
                if (RANGE == range_unsigned)
                    return normalizer * (float) (iSign * iLevel);
                else /* signed range */
                    return normalizer * (float) (iSign * iLevel) + offset;
            }

            /**
             * Update LFO depth with a new external controller value.
             *
             * @param ExtControlValue - new external controller value
             */
            inline void update(const uint16_t& ExtControlValue) {
                const unsigned int intLimit = (unsigned int) -1; // all 0xFFFF...
                const float max = InternalDepth + ExtControlValue * ExtControlDepthCoeff;
                if (RANGE == range_unsigned) {
                    normalizer = max / (float) intLimit * 0.5f;
                } else { // signed range
                    normalizer = max / (float) intLimit * 0.25f;
                    offset     = -max;
                }
            }

            /**
             * Will be called by the voice when the key / voice was triggered.
             *
             * @param Frequency       - frequency of the oscillator in Hz
             * @param StartLevel      - on which level the wave should start
             * @param InternalDepth   - firm, internal oscillator amplitude
             * @param ExtControlDepth - defines how strong the external MIDI
             *                          controller has influence on the
             *                          oscillator amplitude
             * @param FlipPhase       - inverts the oscillator wave
             * @param SampleRate      - current sample rate of the engines
             *                          audio output signal
             */
            void trigger(float Frequency, start_level_t StartLevel, uint16_t InternalDepth, uint16_t ExtControlDepth, bool FlipPhase, unsigned int SampleRate) {
                this->InternalDepth        = (InternalDepth / 1200.0f) * Max;
                this->ExtControlDepthCoeff = (((float) ExtControlDepth / 1200.0f) / 127.0f) * Max;

                const unsigned int intLimit = (unsigned int) -1; // all 0xFFFF...
                const float r = Frequency / (float) SampleRate; // frequency alteration quotient
                c = (int) (intLimit * r);

                switch (StartLevel) {
                    case start_level_max: {
                        c = -c; // wave should go down
                        if (RANGE == range_unsigned)
                            iLevel = intLimit;
                        else /* signed range */
                            iLevel = intLimit >> 1;
                        break;
                    }
                    case start_level_mid: {
                        if (FlipPhase) c = -c; // wave should go down
                        if (RANGE == range_unsigned)
                            iLevel = intLimit >> 1;
                        else /* signed range */
                            iLevel = 0;
                        break;
                    }
                    case start_level_min: {
                        if (RANGE == range_unsigned)
                            iLevel = 0;
                        else /* signed range */
                            iLevel = -(intLimit >> 1);
                        break;
                    }
                }
            }

        private:
            int   iLevel;
            int   c;
            float offset; ///< only needed for signed range
            float normalizer;
    };

} // namespace LinuxSampler

#endif // __LS_LFOTRIANGLEINTMATH_H__
1	/***************************************************************************
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	const float max = InternalDepth + ExtControlValue * ExtControlDepthCoeff;
68	if (RANGE == range_unsigned) {
69	normalizer = max / (float) intLimit * 0.5f;
70	} else { // signed range
71	normalizer = max / (float) intLimit * 0.25f;
72	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	* @param FlipPhase - inverts the oscillator wave
86	* @param SampleRate - current sample rate of the engines
87	* audio output signal
88	*/
89	void trigger(float Frequency, start_level_t StartLevel, uint16_t InternalDepth, uint16_t ExtControlDepth, bool FlipPhase, unsigned int SampleRate) {
90	this->InternalDepth = (InternalDepth / 1200.0f) * Max;
91	this->ExtControlDepthCoeff = (((float) ExtControlDepth / 1200.0f) / 127.0f) * Max;
92
93	const unsigned int intLimit = (unsigned int) -1; // all 0xFFFF...
94	const float r = Frequency / (float) SampleRate; // frequency alteration quotient
95	c = (int) (intLimit * r);
96
97	switch (StartLevel) {
98	case start_level_max: {
99	c = -c; // wave should go down
100	if (RANGE == range_unsigned)
101	iLevel = intLimit;
102	else /* signed range */
103	iLevel = intLimit >> 1;
104	break;
105	}
106	case start_level_mid: {
107	if (FlipPhase) c = -c; // wave should go down
108	if (RANGE == range_unsigned)
109	iLevel = intLimit >> 1;
110	else /* signed range */
111	iLevel = 0;
112	break;
113	}
114	case start_level_min: {
115	if (RANGE == range_unsigned)
116	iLevel = 0;
117	else /* signed range */
118	iLevel = -(intLimit >> 1);
119	break;
120	}
121	}
122	}
123
124	private:
125	int iLevel;
126	int c;
127	float offset; ///< only needed for signed range
128	float normalizer;
129	};
130
131	} // namespace LinuxSampler
132
133	#endif // __LS_LFOTRIANGLEINTMATH_H__