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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.
*
* $URL$
* $Id$
*
*/
/* Tandy/PCJr sequencer for FreeSCI */
#include "sci/sfx/softseq.h"
#include "sci/include/sci_midi.h"
#define FREQUENCY 44100
#define CHANNELS_NR 3
#define VOLUME_SHIFT 3
static int global_volume = 100; /* Base volume */
static int volumes[CHANNELS_NR] = { 100, 100, 100 };
static int notes[CHANNELS_NR] = {0, 0, 0}; /* Current halftone, or 0 if off */
static int freq_count[CHANNELS_NR] = {0, 0, 0};
static int channel_assigner = 0;
static int channels_assigned = 0;
static int chan_nrs[CHANNELS_NR] = { -1, -1, -1};
extern sfx_softseq_t sfx_softseq_pcspeaker;
/* Forward-declare the sequencer we are defining here */
static int
SN76496_set_option(sfx_softseq_t *self, const char *name, const char *value) {
return SFX_ERROR;
}
static int
SN76496_init(sfx_softseq_t *self, byte *patch, int patch_len, byte *patch2,
int patch2_len) {
return SFX_OK;
}
static void
SN76496_exit(sfx_softseq_t *self) {
}
static void
SN76496_event(sfx_softseq_t *self, byte command, int argc, byte *argv) {
int i;
int chan = -1;
#if 0
error("Note [%02x : %02x %02x]\n", command, argc ? argv[0] : 0, (argc > 1) ? argv[1] : 0);
#endif
if ((command & 0xe0) == 0x80) {
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) {
chan = i;
break;
}
} else {
/* 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: */
chan = channel_assigner;
/* Round-ropin iterate channel assigner: */
channel_assigner = (channel_assigner + 1) % CHANNELS_NR;
}
}
#if 0
error(" --> %d [%04x], {%d,%d,%d}@%d\n", chan,
channels_assigned, chan_nrs[0], chan_nrs[1], chan_nrs[2], channel_assigner);
#endif
switch (command & 0xf0) {
case 0x80:
if (argv[0] == notes[chan])
notes[chan] = 0;
break;
case 0x90:
if (!argv[1]) {
if (argv[chan] == notes[chan])
notes[chan] = 0;
} else {
notes[chan] = argv[0];
volumes[chan] = argv[1];
}
break;
case 0xb0:
if (argv[1] == SCI_MIDI_CHANNEL_NOTES_OFF)
notes[chan] = 0;
break;
default:
#if DEBUG
error("[SFX:PCM-PC] Unused MIDI command %02x %02x %02x\n", command, argc ? argv[0] : 0, (argc > 1) ? argv[1] : 0);
#endif
break; /* ignore */
}
}
#define BASE_NOTE 129 /* A10 */
#define BASE_OCTAVE 10 /* A10, as I said */
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
SN76496_poll(sfx_softseq_t *self, byte *dest, int len) {
gint16 *buf = (gint16 *) dest;
int i;
int chan;
int freq[CHANNELS_NR];
for (chan = 0; chan < CHANNELS_NR; chan++)
freq[chan] = get_freq(notes[chan]);
for (i = 0; i < len; i++) {
int 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;
}
}
buf[i] = result;
}
}
void
SN76496_allstop(sfx_softseq_t *self) {
int i;
for (i = 0; i < CHANNELS_NR; i++)
notes[i] = 0;
}
void
SN76496_volume(sfx_softseq_t *self, int new_volume) {
global_volume = new_volume;
}
sfx_softseq_t sfx_softseq_SN76496 = {
"SN76496",
"0.1",
SN76496_set_option,
SN76496_init,
SN76496_exit,
SN76496_volume,
SN76496_event,
SN76496_poll,
SN76496_allstop,
NULL,
SFX_SEQ_PATCHFILE_NONE,
SFX_SEQ_PATCHFILE_NONE,
0x10, /* Tandy/PCJr channels */
0, /* No rhythm channel */
3, /* # of voices */
{FREQUENCY, SFX_PCM_MONO, SFX_PCM_FORMAT_S16_NATIVE}
};
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