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/* 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.
*
* $URL$
* $Id$
*
*/
#include "sci/sfx/softseq.h"
#include "sci/sfx/sci_midi.h"
#include "sci/sfx/softseq/pcjr.h"
namespace Sci {
#define FREQUENCY 44100
#define VOLUME_SHIFT 3
#define BASE_NOTE 129 // A10
#define BASE_OCTAVE 10 // A10, as I said
const static int freq_table[12] = { // A4 is 440Hz, halftone map is x |-> ** 2^(x/12)
28160, // A10
29834,
31608,
33488,
35479,
37589,
39824,
42192,
44701,
47359,
50175,
53159
};
static inline int get_freq(int note) {
int halftone_delta = note - BASE_NOTE;
int oct_diff = ((halftone_delta + BASE_OCTAVE * 12) / 12) - BASE_OCTAVE;
int halftone_index = (halftone_delta + (12 * 100)) % 12 ;
int freq = (!note) ? 0 : freq_table[halftone_index] / (1 << (-oct_diff));
return freq;
}
void MidiDriver_PCJr::send(uint32 b) {
byte command = b & 0xff;
byte op1 = (b >> 8) & 0xff;
byte op2 = (b >> 16) & 0xff;
int i;
int mapped_chan = -1;
int chan_nr = command & 0xf;
// First, test for channel having been assigned already
if (_channels_assigned & (1 << chan_nr)) {
// Already assigned this channel number:
for (i = 0; i < _channels_nr; i++)
if (_chan_nrs[i] == chan_nr) {
mapped_chan = i;
break;
}
} else if ((command & 0xe0) == 0x80) {
// Assign new channel round-robin
// Mark channel as unused:
if (_chan_nrs[_channel_assigner] >= 0)
_channels_assigned &= ~(1 << _chan_nrs[_channel_assigner]);
// Remember channel:
_chan_nrs[_channel_assigner] = chan_nr;
// Mark channel as used
_channels_assigned |= (1 << _chan_nrs[_channel_assigner]);
// Save channel for use later in this call:
mapped_chan = _channel_assigner;
// Round-ropin iterate channel assigner:
_channel_assigner = (_channel_assigner + 1) % _channels_nr;
}
if (mapped_chan == -1)
return;
switch (command & 0xf0) {
case 0x80:
if (op1 == _notes[mapped_chan])
_notes[mapped_chan] = 0;
break;
case 0x90:
if (!op2) {
if (op1 == _notes[mapped_chan])
_notes[mapped_chan] = 0;
} else {
_notes[mapped_chan] = op1;
_volumes[mapped_chan] = op2;
}
break;
case 0xb0:
if ((op1 == SCI_MIDI_CHANNEL_NOTES_OFF) || (op1 == SCI_MIDI_CHANNEL_SOUND_OFF))
_notes[mapped_chan] = 0;
break;
default:
debug(2, "Unused MIDI command %02x %02x %02x", command, op1, op2);
break; /* ignore */
}
}
void MidiDriver_PCJr::generateSamples(int16 *data, int len) {
int i;
int chan;
int freq[kMaxChannels];
for (chan = 0; chan < _channels_nr; chan++)
freq[chan] = get_freq(_notes[chan]);
for (i = 0; i < len; i++) {
int16 result = 0;
for (chan = 0; chan < _channels_nr; chan++)
if (_notes[chan]) {
int volume = (_global_volume * _volumes[chan])
>> VOLUME_SHIFT;
_freq_count[chan] += freq[chan];
while (_freq_count[chan] >= (FREQUENCY << 1))
_freq_count[chan] -= (FREQUENCY << 1);
if (_freq_count[chan] - freq[chan] < 0) {
/* Unclean rising edge */
int l = volume << 1;
result += -volume + (l * _freq_count[chan]) / freq[chan];
} else if (_freq_count[chan] >= FREQUENCY
&& _freq_count[chan] - freq[chan] < FREQUENCY) {
/* Unclean falling edge */
int l = volume << 1;
result += volume - (l * (_freq_count[chan] - FREQUENCY)) / freq[chan];
} else {
if (_freq_count[chan] < FREQUENCY)
result += volume;
else
result += -volume;
}
}
data[i] = result;
}
}
int MidiDriver_PCJr::open(int channels) {
if (_isOpen)
return MERR_ALREADY_OPEN;
if (channels > kMaxChannels)
return -1;
_channels_nr = channels;
_global_volume = 100;
for (int i = 0; i < _channels_nr; i++) {
_volumes[i] = 100;
_notes[i] = 0;
_freq_count[i] = 0;
_chan_nrs[i] = -1;
}
_channel_assigner = 0;
_channels_assigned = 0;
MidiDriver_Emulated::open();
_mixer->playInputStream(Audio::Mixer::kPlainSoundType, &_mixerSoundHandle, this, -1);
return 0;
}
void MidiDriver_PCJr::close() {
_mixer->stopHandle(_mixerSoundHandle);
}
} // End of namespace Sci
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