1 /* ScummVM - Graphic Adventure Engine
2 *
3 * ScummVM is the legal property of its developers, whose names
4 * are too numerous to list here. Please refer to the COPYRIGHT
5 * file distributed with this source distribution.
6 *
7 * This program is free software; you can redistribute it and/or
8 * modify it under the terms of the GNU General Public License
9 * as published by the Free Software Foundation; either version 2
10 * of the License, or (at your option) any later version.
11 *
12 * This program is distributed in the hope that it will be useful,
13 * but WITHOUT ANY WARRANTY; without even the implied warranty of
14 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
15 * GNU General Public License for more details.
16 *
17 * You should have received a copy of the GNU General Public License
18 * along with this program; if not, write to the Free Software
19 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
20 *
21 */
22
23 #include <common/scummsys.h>
24 #include "engines/engine.h"
25 #include "audio/mixer_intern.h"
26 #include "dc.h"
27
28 EXTERN_C void *memcpy4s(void *s1, const void *s2, unsigned int n);
29
initSound()30 uint OSystem_Dreamcast::initSound()
31 {
32 stop_sound();
33 do_sound_command(CMD_SET_FREQ_EXP(FREQ_22050_EXP));
34 do_sound_command(CMD_SET_STEREO(1));
35 do_sound_command(CMD_SET_BUFFER(SOUND_BUFFER_SHIFT));
36 return read_sound_int(&SOUNDSTATUS->freq);
37 }
38
checkSound()39 void OSystem_Dreamcast::checkSound()
40 {
41 int n;
42 int curr_ring_buffer_samples;
43
44 if (!_mixer)
45 return;
46
47 if (read_sound_int(&SOUNDSTATUS->mode) != MODE_PLAY)
48 start_sound();
49
50 curr_ring_buffer_samples = read_sound_int(&SOUNDSTATUS->ring_length);
51
52 n = read_sound_int(&SOUNDSTATUS->samplepos);
53
54 if ((n-=fillpos)<0)
55 n += curr_ring_buffer_samples;
56
57 n = ADJUST_BUFFER_SIZE(n-10);
58
59 if (n<100)
60 return;
61
62 _mixer->mixCallback((byte *)temp_sound_buffer,
63 2*SAMPLES_TO_BYTES(n));
64
65 if (fillpos+n > curr_ring_buffer_samples) {
66 int r = curr_ring_buffer_samples - fillpos;
67 memcpy4s(RING_BUF+fillpos, temp_sound_buffer, SAMPLES_TO_BYTES(r));
68 fillpos = 0;
69 n -= r;
70 memcpy4s(RING_BUF, temp_sound_buffer+r, SAMPLES_TO_BYTES(n));
71 } else {
72 memcpy4s(RING_BUF+fillpos, temp_sound_buffer, SAMPLES_TO_BYTES(n));
73 }
74 if ((fillpos += n) >= curr_ring_buffer_samples)
75 fillpos = 0;
76 }
77