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
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
|
/* 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 3 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, see <http://www.gnu.org/licenses/>.
*
*/
#include "audio/chip.h"
#include "audio/mixer.h"
#include "common/timer.h"
namespace Audio {
void Chip::start(TimerCallback *callback, int timerFrequency) {
_callback.reset(callback);
startCallbacks(timerFrequency);
}
void Chip::stop() {
stopCallbacks();
_callback.reset();
}
RealChip::RealChip() : _baseFreq(0), _remainingTicks(0) {
}
RealChip::~RealChip() {
// Stop callbacks, just in case. If it's still playing at this
// point, there's probably a bigger issue, though. The subclass
// needs to call stop() or the pointer can still use be used in
// the mixer thread at the same time.
stop();
}
void RealChip::setCallbackFrequency(int timerFrequency) {
stopCallbacks();
startCallbacks(timerFrequency);
}
void RealChip::startCallbacks(int timerFrequency) {
_baseFreq = timerFrequency;
assert(_baseFreq > 0);
// We can't request more a timer faster than 100Hz. We'll handle this by calling
// the proc multiple times in onTimer() later on.
if (timerFrequency > kMaxFreq)
timerFrequency = kMaxFreq;
_remainingTicks = 0;
g_system->getTimerManager()->installTimerProc(timerProc, 1000000 / timerFrequency, this, "RealChip");
}
void RealChip::stopCallbacks() {
g_system->getTimerManager()->removeTimerProc(timerProc);
_baseFreq = 0;
_remainingTicks = 0;
}
void RealChip::timerProc(void *refCon) {
static_cast<RealChip *>(refCon)->onTimer();
}
void RealChip::onTimer() {
uint callbacks = 1;
if (_baseFreq > kMaxFreq) {
// We run faster than our max, so run the callback multiple
// times to approximate the actual timer callback frequency.
uint totalTicks = _baseFreq + _remainingTicks;
callbacks = totalTicks / kMaxFreq;
_remainingTicks = totalTicks % kMaxFreq;
}
// Call the callback multiple times. The if is on the inside of the
// loop in case the callback removes itself.
for (uint i = 0; i < callbacks; i++)
if (_callback && _callback->isValid())
(*_callback)();
}
EmulatedChip::EmulatedChip() :
_nextTick(0),
_samplesPerTick(0),
_baseFreq(0),
_handle(new Audio::SoundHandle()) { }
EmulatedChip::~EmulatedChip() {
// Stop callbacks, just in case. If it's still playing at this
// point, there's probably a bigger issue, though. The subclass
// needs to call stop() or the pointer can still use be used in
// the mixer thread at the same time.
stop();
delete _handle;
}
int EmulatedChip::readBuffer(int16 *buffer, 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(buffer, step * stereoFactor);
_nextTick -= step << FIXP_SHIFT;
if (!(_nextTick >> FIXP_SHIFT)) {
if (_callback && _callback->isValid())
(*_callback)();
_nextTick += _samplesPerTick;
}
buffer += step * stereoFactor;
len -= step;
} while (len);
return numSamples;
}
int EmulatedChip::getRate() const {
return g_system->getMixer()->getOutputRate();
}
void EmulatedChip::startCallbacks(int timerFrequency) {
setCallbackFrequency(timerFrequency);
g_system->getMixer()->playStream(Audio::Mixer::kPlainSoundType, _handle, this, -1, Audio::Mixer::kMaxChannelVolume, 0, DisposeAfterUse::NO, true);
}
void EmulatedChip::stopCallbacks() {
g_system->getMixer()->stopHandle(*_handle);
}
void EmulatedChip::setCallbackFrequency(int timerFrequency) {
_baseFreq = timerFrequency;
assert(_baseFreq != 0);
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;
}
} // End of namespace Audio
|
