engines/gig/EGDecay.h

/***************************************************************************
 *                                                                         *
 *   LinuxSampler - modular, streaming capable sampler                     *
 *                                                                         *
 *   Copyright (C) 2003, 2004 by Benno Senoner and Christian Schoenebeck   *
 *   Copyright (C) 2005, 2006 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_GIG_EGDECAY_H__
#define __LS_GIG_EGDECAY_H__

#include "../../common/global.h"
#include "../../common/RTMath.h"

namespace LinuxSampler { namespace gig {

    /** @brief Decay Envelope Generator (linear)
     *
     * Simple Envelope Generator with only one stage: 'Decay' which is a
     * linear segment. The initial envelope level (given by 'Depth') will
     * raise / drop in 'DecayTime' seconds to a level of exactly 1.0. If
     * the initial level ('Depth') is already 1.0, nothing happens.
     */
    class EGDecay {
        public:
            EGDecay();

            /**
             * Will be called by the voice when the key / voice was
             * triggered and initialize the envelope generator.
             *
             * @param Depth      - initial level of the envelope
             * @param DecayTime  - decay time of the envelope (0.000 - 10.000s)
             * @param SampleRate - sample rate of used audio driver
             */
            void trigger(float Depth, float DecayTime, unsigned int SampleRate); //FIXME: we should better use 'float' for SampleRate

            /**
             * Returns true if envelope is still in stage 'Decay', returns
             * false if end of envelope is reached.
             */
            inline bool active() {
                return (bool) Coeff;
            }

            /**
             * Advance envelope by \a SamplePoints steps.
             */
            inline void increment(const int SamplePoints) {
                StepsLeft = RTMath::Max(0, StepsLeft - SamplePoints);
            }

            /**
             * Returns amount of steps until end of envelope is reached.
             */
            inline int toEndLeft() {
                return StepsLeft;
            }

            /**
             * Should be called once the end of the envelope is reached. It
             * will neutralize the envelope coefficient to not alter the
             * envelope anymore and will set the output level to final level
             * of exactly 1.0f. So after this call, render() can still
             * safely be called from the sampler's main synthesis loop.
             */
            inline void update() {
                Level = 1.0f;
                Coeff = 0.0f;
            }

            /**
             * Calculates exactly one level of the envelope.
             *
             * @returns next envelope level
             */
            inline float render() {
                return (Level += Coeff);
            }

            /**
             * Returns the level which this envelope will have in
             * \a SamplePoints steps. It will not alter anything.
             */
            inline float level(const int SamplePoints) const {
                return Level + RTMath::Min(SamplePoints, StepsLeft) * Coeff;
            }

        private:
            float Level;     ///< current EG output level
            float Coeff;     ///< linear coefficient for changing the output level in time
            int   StepsLeft; ///< how many steps left until end is reached
    };

}} // namespace LinuxSampler::gig

#endif // __LS_GIG_EGDECAY_H__
1	/***************************************************************************
2	* *
3	* LinuxSampler - modular, streaming capable sampler *
4	* *
5	* Copyright (C) 2003, 2004 by Benno Senoner and Christian Schoenebeck *
6	* Copyright (C) 2005, 2006 Christian Schoenebeck *
7	* *
8	* This library is free software; you can redistribute it and/or modify *
9	* it under the terms of the GNU General Public License as published by *
10	* the Free Software Foundation; either version 2 of the License, or *
11	* (at your option) any later version. *
12	* *
13	* This library is distributed in the hope that it will be useful, *
14	* but WITHOUT ANY WARRANTY; without even the implied warranty of *
15	* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the *
16	* GNU General Public License for more details. *
17	* *
18	* You should have received a copy of the GNU General Public License *
19	* along with this library; if not, write to the Free Software *
20	* Foundation, Inc., 59 Temple Place, Suite 330, Boston, *
21	* MA 02111-1307 USA *
22	***************************************************************************/
23
24	#ifndef __LS_GIG_EGDECAY_H__
25	#define __LS_GIG_EGDECAY_H__
26
27	#include "../../common/global.h"
28	#include "../../common/RTMath.h"
29
30	namespace LinuxSampler { namespace gig {
31
32	/** @brief Decay Envelope Generator (linear)
33	*
34	* Simple Envelope Generator with only one stage: 'Decay' which is a
35	* linear segment. The initial envelope level (given by 'Depth') will
36	* raise / drop in 'DecayTime' seconds to a level of exactly 1.0. If
37	* the initial level ('Depth') is already 1.0, nothing happens.
38	*/
39	class EGDecay {
40	public:
41	EGDecay();
42
43	/**
44	* Will be called by the voice when the key / voice was
45	* triggered and initialize the envelope generator.
46	*
47	* @param Depth - initial level of the envelope
48	* @param DecayTime - decay time of the envelope (0.000 - 10.000s)
49	* @param SampleRate - sample rate of used audio driver
50	*/
51	void trigger(float Depth, float DecayTime, unsigned int SampleRate); //FIXME: we should better use 'float' for SampleRate
52
53	/**
54	* Returns true if envelope is still in stage 'Decay', returns
55	* false if end of envelope is reached.
56	*/
57	inline bool active() {
58	return (bool) Coeff;
59	}
60
61	/**
62	* Advance envelope by \a SamplePoints steps.
63	*/
64	inline void increment(const int SamplePoints) {
65	StepsLeft = RTMath::Max(0, StepsLeft - SamplePoints);
66	}
67
68	/**
69	* Returns amount of steps until end of envelope is reached.
70	*/
71	inline int toEndLeft() {
72	return StepsLeft;
73	}
74
75	/**
76	* Should be called once the end of the envelope is reached. It
77	* will neutralize the envelope coefficient to not alter the
78	* envelope anymore and will set the output level to final level
79	* of exactly 1.0f. So after this call, render() can still
80	* safely be called from the sampler's main synthesis loop.
81	*/
82	inline void update() {
83	Level = 1.0f;
84	Coeff = 0.0f;
85	}
86
87	/**
88	* Calculates exactly one level of the envelope.
89	*
90	* @returns next envelope level
91	*/
92	inline float render() {
93	return (Level += Coeff);
94	}
95
96	/**
97	* Returns the level which this envelope will have in
98	* \a SamplePoints steps. It will not alter anything.
99	*/
100	inline float level(const int SamplePoints) const {
101	return Level + RTMath::Min(SamplePoints, StepsLeft) * Coeff;
102	}
103
104	private:
105	float Level; ///< current EG output level
106	float Coeff; ///< linear coefficient for changing the output level in time
107	int StepsLeft; ///< how many steps left until end is reached
108	};
109
110	}} // namespace LinuxSampler::gig
111
112	#endif // __LS_GIG_EGDECAY_H__