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
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
|
/* 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.
*
*/
#include "audio/mods/paula.h"
#include "audio/null.h"
namespace Audio {
Paula::Paula(bool stereo, int rate, uint interruptFreq) :
_stereo(stereo), _rate(rate), _periodScale((double)kPalPaulaClock / rate), _intFreq(interruptFreq) {
clearVoices();
_voice[0].panning = 191;
_voice[1].panning = 63;
_voice[2].panning = 63;
_voice[3].panning = 191;
if (_intFreq == 0)
_intFreq = _rate;
_curInt = 0;
_timerBase = 1;
_playing = false;
_end = true;
}
Paula::~Paula() {
}
void Paula::clearVoice(byte voice) {
assert(voice < NUM_VOICES);
_voice[voice].data = 0;
_voice[voice].dataRepeat = 0;
_voice[voice].length = 0;
_voice[voice].lengthRepeat = 0;
_voice[voice].period = 0;
_voice[voice].volume = 0;
_voice[voice].offset = Offset(0);
_voice[voice].dmaCount = 0;
}
int Paula::readBuffer(int16 *buffer, const int numSamples) {
Common::StackLock lock(_mutex);
memset(buffer, 0, numSamples * 2);
if (!_playing) {
return numSamples;
}
if (_stereo)
return readBufferIntern<true>(buffer, numSamples);
else
return readBufferIntern<false>(buffer, numSamples);
}
template<bool stereo>
inline int mixBuffer(int16 *&buf, const int8 *data, Paula::Offset &offset, frac_t rate, int neededSamples, uint bufSize, byte volume, byte panning) {
int samples;
for (samples = 0; samples < neededSamples && offset.int_off < bufSize; ++samples) {
const int32 tmp = ((int32) data[offset.int_off]) * volume;
if (stereo) {
*buf++ += (tmp * (255 - panning)) >> 7;
*buf++ += (tmp * (panning)) >> 7;
} else
*buf++ += tmp;
// Step to next source sample
offset.rem_off += rate;
if (offset.rem_off >= (frac_t)FRAC_ONE) {
offset.int_off += fracToInt(offset.rem_off);
offset.rem_off &= FRAC_LO_MASK;
}
}
return samples;
}
template<bool stereo>
int Paula::readBufferIntern(int16 *buffer, const int numSamples) {
int samples = _stereo ? numSamples / 2 : numSamples;
while (samples > 0) {
// Handle 'interrupts'. This gives subclasses the chance to adjust the channel data
// (e.g. insert new samples, do pitch bending, whatever).
if (_curInt == 0) {
_curInt = _intFreq;
interrupt();
}
// Compute how many samples to generate: at most the requested number of samples,
// of course, but we may stop earlier when an 'interrupt' is expected.
const uint nSamples = MIN((uint)samples, _curInt);
// Loop over the four channels of the emulated Paula chip
for (int voice = 0; voice < NUM_VOICES; voice++) {
// No data, or paused -> skip channel
if (!_voice[voice].data || (_voice[voice].period <= 0))
continue;
// The Paula chip apparently run at 7.0937892 MHz in the PAL
// version and at 7.1590905 MHz in the NTSC version. We divide this
// by the requested the requested output sampling rate _rate
// (typically 44.1 kHz or 22.05 kHz) obtaining the value _periodScale.
// This is then divided by the "period" of the channel we are
// processing, to obtain the correct output 'rate'.
frac_t rate = doubleToFrac(_periodScale / _voice[voice].period);
// Cap the volume
_voice[voice].volume = MIN((byte) 0x40, _voice[voice].volume);
Channel &ch = _voice[voice];
int16 *p = buffer;
int neededSamples = nSamples;
// NOTE: A Protracker (or other module format) player might actually
// push the offset past the sample length in its interrupt(), in which
// case the first mixBuffer() call should not mix anything, and the loop
// should be triggered.
// Thus, doing an assert(ch.offset.int_off < ch.length) here is wrong.
// An example where this happens is a certain Protracker module played
// by the OS/2 version of Hopkins FBI.
// Mix the generated samples into the output buffer
neededSamples -= mixBuffer<stereo>(p, ch.data, ch.offset, rate, neededSamples, ch.length, ch.volume, ch.panning);
// Wrap around if necessary
if (ch.offset.int_off >= ch.length) {
// Important: Wrap around the offset *before* updating the voice length.
// Otherwise, if length != lengthRepeat we would wrap incorrectly.
// Note: If offset >= 2*len ever occurs, the following would be wrong;
// instead of subtracting, we then should compute the modulus using "%=".
// Since that requires a division and is slow, and shouldn't be necessary
// in practice anyway, we only use subtraction.
ch.offset.int_off -= ch.length;
ch.dmaCount++;
ch.data = ch.dataRepeat;
ch.length = ch.lengthRepeat;
}
// If we have not yet generated enough samples, and looping is active: loop!
if (neededSamples > 0 && ch.length > 2) {
// Repeat as long as necessary.
while (neededSamples > 0) {
// Mix the generated samples into the output buffer
neededSamples -= mixBuffer<stereo>(p, ch.data, ch.offset, rate, neededSamples, ch.length, ch.volume, ch.panning);
if (ch.offset.int_off >= ch.length) {
// Wrap around. See also the note above.
ch.offset.int_off -= ch.length;
ch.dmaCount++;
}
}
}
}
buffer += _stereo ? nSamples * 2 : nSamples;
_curInt -= nSamples;
samples -= nSamples;
}
return numSamples;
}
} // End of namespace Audio
// Plugin interface
// (This can only create a null driver since apple II gs support seeems not to be implemented
// and also is not part of the midi driver architecture. But we need the plugin for the options
// menu in the launcher and for MidiDriver::detectDevice() which is more or less used by all engines.)
class AmigaMusicPlugin : public NullMusicPlugin {
public:
const char *getName() const {
return _s("Amiga Audio emulator");
}
const char *getId() const {
return "amiga";
}
MusicDevices getDevices() const;
};
MusicDevices AmigaMusicPlugin::getDevices() const {
MusicDevices devices;
devices.push_back(MusicDevice(this, "", MT_AMIGA));
return devices;
}
//#if PLUGIN_ENABLED_DYNAMIC(AMIGA)
//REGISTER_PLUGIN_DYNAMIC(AMIGA, PLUGIN_TYPE_MUSIC, AmigaMusicPlugin);
//#else
REGISTER_PLUGIN_STATIC(AMIGA, PLUGIN_TYPE_MUSIC, AmigaMusicPlugin);
//#endif
|
