SDL_dspaudio.c
1
2
/*
SDL - Simple DirectMedia Layer
3
Copyright (C) 1997-2006 Sam Lantinga
4
5
This library is free software; you can redistribute it and/or
6
modify it under the terms of the GNU Lesser General Public
7
License as published by the Free Software Foundation; either
8
version 2.1 of the License, or (at your option) any later version.
9
10
11
12
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
13
Lesser General Public License for more details.
15
16
17
You should have received a copy of the GNU Lesser General Public
License along with this library; if not, write to the Free Software
Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
18
19
Sam Lantinga
20
slouken@libsdl.org
21
22
23
Modified in Oct 2004 by Hannu Savolainen
hannu@opensound.com
24
*/
25
#include "SDL_config.h"
26
27
28
/* Allow access to a raw mixing buffer */
29
30
#include <stdio.h> /* For perror() */
#include <string.h> /* For strerror() */
31
32
33
34
35
36
37
#include <errno.h>
#include <unistd.h>
#include <fcntl.h>
#include <signal.h>
#include <sys/time.h>
#include <sys/ioctl.h>
#include <sys/stat.h>
38
39
#if SDL_AUDIO_DRIVER_OSS_SOUNDCARD_H
40
41
42
43
/* This is installed on some systems */
#include <soundcard.h>
#else
/* This is recommended by OSS */
44
#include <sys/soundcard.h>
47
#include "SDL_timer.h"
48
#include "SDL_audio.h"
49
50
51
#include "../SDL_audiomem.h"
#include "../SDL_audio_c.h"
#include "../SDL_audiodev_c.h"
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
#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)
{
85
86
SDL_free(device->hidden);
SDL_free(device);
87
88
89
90
91
92
93
}
static SDL_AudioDevice *Audio_CreateDevice(int devindex)
{
SDL_AudioDevice *this;
/* Initialize all variables that we clean on shutdown */
94
this = (SDL_AudioDevice *)SDL_malloc(sizeof(SDL_AudioDevice));
95
if ( this ) {
96
SDL_memset(this, 0, (sizeof *this));
97
this->hidden = (struct SDL_PrivateAudioData *)
98
SDL_malloc((sizeof *this->hidden));
99
100
101
102
}
if ( (this == NULL) || (this->hidden == NULL) ) {
SDL_OutOfMemory();
if ( this ) {
103
SDL_free(this);
104
105
106
}
return(0);
}
107
SDL_memset(this->hidden, 0, (sizeof *this->hidden));
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
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)
{
130
/* Not needed at all since OSS handles waiting automagically */
131
132
133
134
}
static void DSP_PlayAudio(_THIS)
{
135
136
137
if (write(audio_fd, mixbuf, mixlen)==-1)
{
perror("Audio write");
138
139
this->enabled = 0;
}
141
#ifdef DEBUG_AUDIO
142
fprintf(stderr, "Wrote %d bytes of audio data\n", mixlen);
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
#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;
168
int frag_spec;
169
170
171
172
173
174
175
176
177
178
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;
179
180
181
182
183
184
/* 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");
185
DSP_CloseAudio(this);
186
187
188
189
return(-1);
}
}
190
191
/* Get a list of supported hardware formats */
if ( ioctl(audio_fd, SNDCTL_DSP_GETFMTS, &value) < 0 ) {
192
perror("SNDCTL_DSP_GETFMTS");
193
SDL_SetError("Couldn't get audio format list");
194
DSP_CloseAudio(this);
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
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;
221
222
223
224
225
226
227
228
229
230
#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;
231
232
233
234
235
236
237
238
239
240
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;
242
default:
243
format = 0;
244
245
246
247
248
249
250
251
break;
}
if ( ! format ) {
test_format = SDL_NextAudioFormat();
}
}
if ( format == 0 ) {
SDL_SetError("Couldn't find any hardware audio formats");
252
DSP_CloseAudio(this);
253
254
255
256
257
258
259
260
return(-1);
}
spec->format = test_format;
/* Set the audio format */
value = format;
if ( (ioctl(audio_fd, SNDCTL_DSP_SETFMT, &value) < 0) ||
(value != format) ) {
261
perror("SNDCTL_DSP_SETFMT");
262
SDL_SetError("Couldn't set audio format");
263
DSP_CloseAudio(this);
264
265
266
267
268
269
return(-1);
}
/* Set the number of channels of output */
value = spec->channels;
if ( ioctl(audio_fd, SNDCTL_DSP_CHANNELS, &value) < 0 ) {
270
271
perror("SNDCTL_DSP_CHANNELS");
SDL_SetError("Cannot set the number of channels");
272
DSP_CloseAudio(this);
273
return(-1);
274
275
276
}
spec->channels = value;
277
278
279
280
281
/* 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");
282
DSP_CloseAudio(this);
283
284
285
286
287
288
289
290
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 */
291
292
for ( frag_spec = 0; (0x01U<<frag_spec) < spec->size; ++frag_spec );
if ( (0x01U<<frag_spec) != spec->size ) {
293
SDL_SetError("Fragment size must be a power of two");
294
DSP_CloseAudio(this);
295
296
return(-1);
}
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
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");
}
#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
316
317
318
319
320
/* Allocate mixing buffer */
mixlen = spec->size;
mixbuf = (Uint8 *)SDL_AllocAudioMem(mixlen);
if ( mixbuf == NULL ) {
321
DSP_CloseAudio(this);
322
323
return(-1);
}
324
SDL_memset(mixbuf, spec->silence, spec->size);
325
326
327
328
329
330
331
/* Get the parent process id (we're the parent of the audio thread) */
parent = getpid();
/* We're ready to rock and roll. :-) */
return(0);
}