1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
|
/* ScummVM - Graphic Adventure Engine
*
* ScummVM is the legal property of its developers, whose names
* are too numerous to list here. Please refer to the COPYRIGHT
* file distributed with this source distribution.
*
* This program 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 program 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 program; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
*
*/
#ifndef AUDIO_SOFTSYNTH_EMUMIDI_H
#define AUDIO_SOFTSYNTH_EMUMIDI_H
#include "audio/audiostream.h"
#include "audio/mididrv.h"
#include "audio/mixer.h"
class MidiDriver_Emulated : public Audio::AudioStream, public MidiDriver {
protected:
bool _isOpen;
Audio::Mixer *_mixer;
Audio::SoundHandle _mixerSoundHandle;
private:
Common::TimerManager::TimerProc _timerProc;
void *_timerParam;
enum {
FIXP_SHIFT = 16
};
int _nextTick;
int _samplesPerTick;
protected:
int _baseFreq;
virtual void generateSamples(int16 *buf, int len) = 0;
virtual void onTimer() {}
public:
MidiDriver_Emulated(Audio::Mixer *mixer) :
_mixer(mixer),
_isOpen(false),
_timerProc(0),
_timerParam(0),
_nextTick(0),
_samplesPerTick(0),
_baseFreq(250) {
}
// MidiDriver API
virtual int open() {
_isOpen = true;
int d = getRate() / _baseFreq;
int r = getRate() % _baseFreq;
// This is equivalent to (getRate() << FIXP_SHIFT) / BASE_FREQ
// but less prone to arithmetic overflow.
_samplesPerTick = (d << FIXP_SHIFT) + (r << FIXP_SHIFT) / _baseFreq;
return 0;
}
bool isOpen() const { return _isOpen; }
virtual void setTimerCallback(void *timer_param, Common::TimerManager::TimerProc timer_proc) {
_timerProc = timer_proc;
_timerParam = timer_param;
}
virtual uint32 getBaseTempo() {
return 1000000 / _baseFreq;
}
// AudioStream API
virtual int readBuffer(int16 *data, const int numSamples) {
const int stereoFactor = isStereo() ? 2 : 1;
int len = numSamples / stereoFactor;
int step;
do {
step = len;
if (step > (_nextTick >> FIXP_SHIFT))
step = (_nextTick >> FIXP_SHIFT);
generateSamples(data, step);
_nextTick -= step << FIXP_SHIFT;
if (!(_nextTick >> FIXP_SHIFT)) {
if (_timerProc)
(*_timerProc)(_timerParam);
onTimer();
_nextTick += _samplesPerTick;
}
data += step * stereoFactor;
len -= step;
} while (len);
return numSamples;
}
virtual bool endOfData() const {
return false;
}
};
#endif
|
