/
SDL_dspaudio.c
337 lines (296 loc) · 7.99 KB
1
2
/*
SDL - Simple DirectMedia Layer
3
Copyright (C) 1997-2004 Sam Lantinga
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
This library is free software; you can redistribute it and/or
modify it under the terms of the GNU Library General Public
License as published by the Free Software Foundation; either
version 2 of the License, or (at your option) any later version.
This library 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
Library General Public License for more details.
You should have received a copy of the GNU Library General Public
License along with this library; if not, write to the Free
Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
Sam Lantinga
20
slouken@libsdl.org
21
22
23
Modified in Oct 2004 by Hannu Savolainen
hannu@opensound.com
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
*/
#ifdef SAVE_RCSID
static char rcsid =
"@(#) $Id$";
#endif
/* Allow access to a raw mixing buffer */
#include <stdlib.h>
#include <stdio.h>
#include <string.h>
#include <errno.h>
#include <unistd.h>
#include <fcntl.h>
#include <signal.h>
#include <sys/time.h>
#include <sys/ioctl.h>
#include <sys/stat.h>
43
44
45
46
47
#ifdef OSS_USE_SOUNDCARD_H
/* This is installed on some systems */
#include <soundcard.h>
#else
/* This is recommended by OSS */
48
#include <sys/soundcard.h>
49
#endif
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
#include "SDL_audio.h"
#include "SDL_error.h"
#include "SDL_audiomem.h"
#include "SDL_audio_c.h"
#include "SDL_timer.h"
#include "SDL_audiodev_c.h"
#include "SDL_dspaudio.h"
/* The tag name used by DSP audio */
#define DSP_DRIVER_NAME "dsp"
/* Open the audio device for playback, and don't block if busy */
#define OPEN_FLAGS (O_WRONLY|O_NONBLOCK)
/* Audio driver functions */
static int DSP_OpenAudio(_THIS, SDL_AudioSpec *spec);
static void DSP_WaitAudio(_THIS);
static void DSP_PlayAudio(_THIS);
static Uint8 *DSP_GetAudioBuf(_THIS);
static void DSP_CloseAudio(_THIS);
/* Audio driver bootstrap functions */
static int Audio_Available(void)
{
int fd;
int available;
available = 0;
fd = SDL_OpenAudioPath(NULL, 0, OPEN_FLAGS, 0);
if ( fd >= 0 ) {
available = 1;
close(fd);
}
return(available);
}
static void Audio_DeleteDevice(SDL_AudioDevice *device)
{
free(device->hidden);
free(device);
}
static SDL_AudioDevice *Audio_CreateDevice(int devindex)
{
SDL_AudioDevice *this;
/* Initialize all variables that we clean on shutdown */
this = (SDL_AudioDevice *)malloc(sizeof(SDL_AudioDevice));
if ( this ) {
memset(this, 0, (sizeof *this));
this->hidden = (struct SDL_PrivateAudioData *)
malloc((sizeof *this->hidden));
}
if ( (this == NULL) || (this->hidden == NULL) ) {
SDL_OutOfMemory();
if ( this ) {
free(this);
}
return(0);
}
memset(this->hidden, 0, (sizeof *this->hidden));
audio_fd = -1;
/* Set the function pointers */
this->OpenAudio = DSP_OpenAudio;
this->WaitAudio = DSP_WaitAudio;
this->PlayAudio = DSP_PlayAudio;
this->GetAudioBuf = DSP_GetAudioBuf;
this->CloseAudio = DSP_CloseAudio;
this->free = Audio_DeleteDevice;
return this;
}
AudioBootStrap DSP_bootstrap = {
DSP_DRIVER_NAME, "OSS /dev/dsp standard audio",
Audio_Available, Audio_CreateDevice
};
/* This function waits until it is possible to write a full sound buffer */
static void DSP_WaitAudio(_THIS)
{
135
/* Not needed at all since OSS handles waiting automagically */
136
137
138
139
}
static void DSP_PlayAudio(_THIS)
{
140
141
142
if (write(audio_fd, mixbuf, mixlen)==-1)
{
perror("Audio write");
143
144
this->enabled = 0;
}
145
146
#ifdef DEBUG_AUDIO
147
fprintf(stderr, "Wrote %d bytes of audio data\n", mixlen);
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
#endif
}
static Uint8 *DSP_GetAudioBuf(_THIS)
{
return(mixbuf);
}
static void DSP_CloseAudio(_THIS)
{
if ( mixbuf != NULL ) {
SDL_FreeAudioMem(mixbuf);
mixbuf = NULL;
}
if ( audio_fd >= 0 ) {
close(audio_fd);
audio_fd = -1;
}
}
static int DSP_OpenAudio(_THIS, SDL_AudioSpec *spec)
{
char audiodev[1024];
int format;
int value;
173
int frag_spec;
174
175
176
177
178
179
180
181
182
183
Uint16 test_format;
/* Open the audio device */
audio_fd = SDL_OpenAudioPath(audiodev, sizeof(audiodev), OPEN_FLAGS, 0);
if ( audio_fd < 0 ) {
SDL_SetError("Couldn't open %s: %s", audiodev, strerror(errno));
return(-1);
}
mixbuf = NULL;
184
185
186
187
188
189
/* Make the file descriptor use blocking writes with fcntl() */
{ long flags;
flags = fcntl(audio_fd, F_GETFL);
flags &= ~O_NONBLOCK;
if ( fcntl(audio_fd, F_SETFL, flags) < 0 ) {
SDL_SetError("Couldn't set audio blocking mode");
190
DSP_CloseAudio(this);
191
192
193
194
return(-1);
}
}
195
196
/* Get a list of supported hardware formats */
if ( ioctl(audio_fd, SNDCTL_DSP_GETFMTS, &value) < 0 ) {
197
perror("SNDCTL_DSP_GETFMTS");
198
SDL_SetError("Couldn't get audio format list");
199
DSP_CloseAudio(this);
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
return(-1);
}
/* Try for a closest match on audio format */
format = 0;
for ( test_format = SDL_FirstAudioFormat(spec->format);
! format && test_format; ) {
#ifdef DEBUG_AUDIO
fprintf(stderr, "Trying format 0x%4.4x\n", test_format);
#endif
switch ( test_format ) {
case AUDIO_U8:
if ( value & AFMT_U8 ) {
format = AFMT_U8;
}
break;
case AUDIO_S16LSB:
if ( value & AFMT_S16_LE ) {
format = AFMT_S16_LE;
}
break;
case AUDIO_S16MSB:
if ( value & AFMT_S16_BE ) {
format = AFMT_S16_BE;
}
break;
226
227
228
229
230
231
232
233
234
235
#if 0
/*
* These formats are not used by any real life systems so they are not
* needed here.
*/
case AUDIO_S8:
if ( value & AFMT_S8 ) {
format = AFMT_S8;
}
break;
236
237
238
239
240
241
242
243
244
245
case AUDIO_U16LSB:
if ( value & AFMT_U16_LE ) {
format = AFMT_U16_LE;
}
break;
case AUDIO_U16MSB:
if ( value & AFMT_U16_BE ) {
format = AFMT_U16_BE;
}
break;
246
#endif
247
default:
248
format = 0;
249
250
251
252
253
254
255
256
break;
}
if ( ! format ) {
test_format = SDL_NextAudioFormat();
}
}
if ( format == 0 ) {
SDL_SetError("Couldn't find any hardware audio formats");
257
DSP_CloseAudio(this);
258
259
260
261
262
263
264
265
return(-1);
}
spec->format = test_format;
/* Set the audio format */
value = format;
if ( (ioctl(audio_fd, SNDCTL_DSP_SETFMT, &value) < 0) ||
(value != format) ) {
266
perror("SNDCTL_DSP_SETFMT");
267
SDL_SetError("Couldn't set audio format");
268
DSP_CloseAudio(this);
269
270
271
272
273
274
return(-1);
}
/* Set the number of channels of output */
value = spec->channels;
if ( ioctl(audio_fd, SNDCTL_DSP_CHANNELS, &value) < 0 ) {
275
276
perror("SNDCTL_DSP_CHANNELS");
SDL_SetError("Cannot set the number of channels");
277
DSP_CloseAudio(this);
278
return(-1);
279
280
281
}
spec->channels = value;
282
283
284
285
286
/* Set the DSP frequency */
value = spec->freq;
if ( ioctl(audio_fd, SNDCTL_DSP_SPEED, &value) < 0 ) {
perror("SNDCTL_DSP_SPEED");
SDL_SetError("Couldn't set audio frequency");
287
DSP_CloseAudio(this);
288
289
290
291
292
293
294
295
296
297
298
return(-1);
}
spec->freq = value;
/* Calculate the final parameters for this audio specification */
SDL_CalculateAudioSpec(spec);
/* Determine the power of two of the fragment size */
for ( frag_spec = 0; (0x01<<frag_spec) < spec->size; ++frag_spec );
if ( (0x01<<frag_spec) != spec->size ) {
SDL_SetError("Fragment size must be a power of two");
299
DSP_CloseAudio(this);
300
301
return(-1);
}
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
frag_spec |= 0x00020000; /* two fragments, for low latency */
/* Set the audio buffering parameters */
#ifdef DEBUG_AUDIO
fprintf(stderr, "Requesting %d fragments of size %d\n",
(frag_spec >> 16), 1<<(frag_spec&0xFFFF));
#endif
if ( ioctl(audio_fd, SNDCTL_DSP_SETFRAGMENT, &frag_spec) < 0 ) {
perror("SNDCTL_DSP_SETFRAGMENT");
fprintf(stderr, "Warning: Couldn't set audio fragment size\n");
}
#ifdef DEBUG_AUDIO
{ audio_buf_info info;
ioctl(audio_fd, SNDCTL_DSP_GETOSPACE, &info);
fprintf(stderr, "fragments = %d\n", info.fragments);
fprintf(stderr, "fragstotal = %d\n", info.fragstotal);
fprintf(stderr, "fragsize = %d\n", info.fragsize);
fprintf(stderr, "bytes = %d\n", info.bytes);
}
#endif
322
323
324
325
326
/* Allocate mixing buffer */
mixlen = spec->size;
mixbuf = (Uint8 *)SDL_AllocAudioMem(mixlen);
if ( mixbuf == NULL ) {
327
DSP_CloseAudio(this);
328
329
330
331
332
333
334
335
336
337
return(-1);
}
memset(mixbuf, spec->silence, spec->size);
/* Get the parent process id (we're the parent of the audio thread) */
parent = getpid();
/* We're ready to rock and roll. :-) */
return(0);
}