1 /*
2 SDL - Simple DirectMedia Layer
3 Copyright (C) 1997-2012 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 This library is distributed in the hope that it will be useful,
11 but WITHOUT ANY WARRANTY; without even the implied warranty of
12 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
13 Lesser General Public License for more details.
14
15 You should have received a copy of the GNU Lesser General Public
16 License along with this library; if not, write to the Free Software
17 Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
18
19 Sam Lantinga
20 slouken@libsdl.org
21
22 Modified in Oct 2004 by Hannu Savolainen
23 hannu@opensound.com
24 */
25 #include "SDL_config.h"
26
27 /* Allow access to a raw mixing buffer */
28
29 #include <stdio.h> /* For perror() */
30 #include <string.h> /* For strerror() */
31 #include <errno.h>
32 #include <unistd.h>
33 #include <fcntl.h>
34 #include <signal.h>
35 #include <sys/time.h>
36 #include <sys/ioctl.h>
37 #include <sys/stat.h>
38
39 #if SDL_AUDIO_DRIVER_OSS_SOUNDCARD_H
40 /* This is installed on some systems */
41 #include <soundcard.h>
42 #else
43 /* This is recommended by OSS */
44 #include <sys/soundcard.h>
45 #endif
46
47 #include "SDL_timer.h"
48 #include "SDL_audio.h"
49 #include "../SDL_audiomem.h"
50 #include "../SDL_audio_c.h"
51 #include "../SDL_audiodev_c.h"
52 #include "SDL_dspaudio.h"
53
54 /* The tag name used by DSP audio */
55 #define DSP_DRIVER_NAME "dsp"
56
57 /* Open the audio device for playback, and don't block if busy */
58 #define OPEN_FLAGS (O_WRONLY|O_NONBLOCK)
59
60 /* Audio driver functions */
61 static int DSP_OpenAudio(_THIS, SDL_AudioSpec *spec);
62 static void DSP_WaitAudio(_THIS);
63 static void DSP_PlayAudio(_THIS);
64 static Uint8 *DSP_GetAudioBuf(_THIS);
65 static void DSP_CloseAudio(_THIS);
66
67 /* Audio driver bootstrap functions */
68
Audio_Available(void)69 static int Audio_Available(void)
70 {
71 int fd;
72 int available;
73
74 available = 0;
75 fd = SDL_OpenAudioPath(NULL, 0, OPEN_FLAGS, 0);
76 if ( fd >= 0 ) {
77 available = 1;
78 close(fd);
79 }
80 return(available);
81 }
82
Audio_DeleteDevice(SDL_AudioDevice * device)83 static void Audio_DeleteDevice(SDL_AudioDevice *device)
84 {
85 SDL_free(device->hidden);
86 SDL_free(device);
87 }
88
Audio_CreateDevice(int devindex)89 static SDL_AudioDevice *Audio_CreateDevice(int devindex)
90 {
91 SDL_AudioDevice *this;
92
93 /* 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 if ( (this == NULL) || (this->hidden == NULL) ) {
101 SDL_OutOfMemory();
102 if ( this ) {
103 SDL_free(this);
104 }
105 return(0);
106 }
107 SDL_memset(this->hidden, 0, (sizeof *this->hidden));
108 audio_fd = -1;
109
110 /* Set the function pointers */
111 this->OpenAudio = DSP_OpenAudio;
112 this->WaitAudio = DSP_WaitAudio;
113 this->PlayAudio = DSP_PlayAudio;
114 this->GetAudioBuf = DSP_GetAudioBuf;
115 this->CloseAudio = DSP_CloseAudio;
116
117 this->free = Audio_DeleteDevice;
118
119 return this;
120 }
121
122 AudioBootStrap DSP_bootstrap = {
123 DSP_DRIVER_NAME, "OSS /dev/dsp standard audio",
124 Audio_Available, Audio_CreateDevice
125 };
126
127 /* This function waits until it is possible to write a full sound buffer */
DSP_WaitAudio(_THIS)128 static void DSP_WaitAudio(_THIS)
129 {
130 /* Not needed at all since OSS handles waiting automagically */
131 }
132
DSP_PlayAudio(_THIS)133 static void DSP_PlayAudio(_THIS)
134 {
135 if (write(audio_fd, mixbuf, mixlen)==-1)
136 {
137 perror("Audio write");
138 this->enabled = 0;
139 }
140
141 #ifdef DEBUG_AUDIO
142 fprintf(stderr, "Wrote %d bytes of audio data\n", mixlen);
143 #endif
144 }
145
DSP_GetAudioBuf(_THIS)146 static Uint8 *DSP_GetAudioBuf(_THIS)
147 {
148 return(mixbuf);
149 }
150
DSP_CloseAudio(_THIS)151 static void DSP_CloseAudio(_THIS)
152 {
153 if ( mixbuf != NULL ) {
154 SDL_FreeAudioMem(mixbuf);
155 mixbuf = NULL;
156 }
157 if ( audio_fd >= 0 ) {
158 close(audio_fd);
159 audio_fd = -1;
160 }
161 }
162
DSP_OpenAudio(_THIS,SDL_AudioSpec * spec)163 static int DSP_OpenAudio(_THIS, SDL_AudioSpec *spec)
164 {
165 char audiodev[1024];
166 int format;
167 int value;
168 int frag_spec;
169 Uint16 test_format;
170
171 /* Make sure fragment size stays a power of 2, or OSS fails. */
172 /* I don't know which of these are actually legal values, though... */
173 if (spec->channels > 8)
174 spec->channels = 8;
175 else if (spec->channels > 4)
176 spec->channels = 4;
177 else if (spec->channels > 2)
178 spec->channels = 2;
179
180 /* Open the audio device */
181 audio_fd = SDL_OpenAudioPath(audiodev, sizeof(audiodev), OPEN_FLAGS, 0);
182 if ( audio_fd < 0 ) {
183 SDL_SetError("Couldn't open %s: %s", audiodev, strerror(errno));
184 return(-1);
185 }
186 mixbuf = NULL;
187
188 /* Make the file descriptor use blocking writes with fcntl() */
189 { long flags;
190 flags = fcntl(audio_fd, F_GETFL);
191 flags &= ~O_NONBLOCK;
192 if ( fcntl(audio_fd, F_SETFL, flags) < 0 ) {
193 SDL_SetError("Couldn't set audio blocking mode");
194 DSP_CloseAudio(this);
195 return(-1);
196 }
197 }
198
199 /* Get a list of supported hardware formats */
200 if ( ioctl(audio_fd, SNDCTL_DSP_GETFMTS, &value) < 0 ) {
201 perror("SNDCTL_DSP_GETFMTS");
202 SDL_SetError("Couldn't get audio format list");
203 DSP_CloseAudio(this);
204 return(-1);
205 }
206
207 /* Try for a closest match on audio format */
208 format = 0;
209 for ( test_format = SDL_FirstAudioFormat(spec->format);
210 ! format && test_format; ) {
211 #ifdef DEBUG_AUDIO
212 fprintf(stderr, "Trying format 0x%4.4x\n", test_format);
213 #endif
214 switch ( test_format ) {
215 case AUDIO_U8:
216 if ( value & AFMT_U8 ) {
217 format = AFMT_U8;
218 }
219 break;
220 case AUDIO_S16LSB:
221 if ( value & AFMT_S16_LE ) {
222 format = AFMT_S16_LE;
223 }
224 break;
225 case AUDIO_S16MSB:
226 if ( value & AFMT_S16_BE ) {
227 format = AFMT_S16_BE;
228 }
229 break;
230 #if 0
231 /*
232 * These formats are not used by any real life systems so they are not
233 * needed here.
234 */
235 case AUDIO_S8:
236 if ( value & AFMT_S8 ) {
237 format = AFMT_S8;
238 }
239 break;
240 case AUDIO_U16LSB:
241 if ( value & AFMT_U16_LE ) {
242 format = AFMT_U16_LE;
243 }
244 break;
245 case AUDIO_U16MSB:
246 if ( value & AFMT_U16_BE ) {
247 format = AFMT_U16_BE;
248 }
249 break;
250 #endif
251 default:
252 format = 0;
253 break;
254 }
255 if ( ! format ) {
256 test_format = SDL_NextAudioFormat();
257 }
258 }
259 if ( format == 0 ) {
260 SDL_SetError("Couldn't find any hardware audio formats");
261 DSP_CloseAudio(this);
262 return(-1);
263 }
264 spec->format = test_format;
265
266 /* Set the audio format */
267 value = format;
268 if ( (ioctl(audio_fd, SNDCTL_DSP_SETFMT, &value) < 0) ||
269 (value != format) ) {
270 perror("SNDCTL_DSP_SETFMT");
271 SDL_SetError("Couldn't set audio format");
272 DSP_CloseAudio(this);
273 return(-1);
274 }
275
276 /* Set the number of channels of output */
277 value = spec->channels;
278 if ( ioctl(audio_fd, SNDCTL_DSP_CHANNELS, &value) < 0 ) {
279 perror("SNDCTL_DSP_CHANNELS");
280 SDL_SetError("Cannot set the number of channels");
281 DSP_CloseAudio(this);
282 return(-1);
283 }
284 spec->channels = value;
285
286 /* Set the DSP frequency */
287 value = spec->freq;
288 if ( ioctl(audio_fd, SNDCTL_DSP_SPEED, &value) < 0 ) {
289 perror("SNDCTL_DSP_SPEED");
290 SDL_SetError("Couldn't set audio frequency");
291 DSP_CloseAudio(this);
292 return(-1);
293 }
294 spec->freq = value;
295
296 /* Calculate the final parameters for this audio specification */
297 SDL_CalculateAudioSpec(spec);
298
299 /* Determine the power of two of the fragment size */
300 for ( frag_spec = 0; (0x01U<<frag_spec) < spec->size; ++frag_spec );
301 if ( (0x01U<<frag_spec) != spec->size ) {
302 SDL_SetError("Fragment size must be a power of two");
303 DSP_CloseAudio(this);
304 return(-1);
305 }
306 frag_spec |= 0x00020000; /* two fragments, for low latency */
307
308 /* Set the audio buffering parameters */
309 #ifdef DEBUG_AUDIO
310 fprintf(stderr, "Requesting %d fragments of size %d\n",
311 (frag_spec >> 16), 1<<(frag_spec&0xFFFF));
312 #endif
313 if ( ioctl(audio_fd, SNDCTL_DSP_SETFRAGMENT, &frag_spec) < 0 ) {
314 perror("SNDCTL_DSP_SETFRAGMENT");
315 }
316 #ifdef DEBUG_AUDIO
317 { audio_buf_info info;
318 ioctl(audio_fd, SNDCTL_DSP_GETOSPACE, &info);
319 fprintf(stderr, "fragments = %d\n", info.fragments);
320 fprintf(stderr, "fragstotal = %d\n", info.fragstotal);
321 fprintf(stderr, "fragsize = %d\n", info.fragsize);
322 fprintf(stderr, "bytes = %d\n", info.bytes);
323 }
324 #endif
325
326 /* Allocate mixing buffer */
327 mixlen = spec->size;
328 mixbuf = (Uint8 *)SDL_AllocAudioMem(mixlen);
329 if ( mixbuf == NULL ) {
330 DSP_CloseAudio(this);
331 return(-1);
332 }
333 SDL_memset(mixbuf, spec->silence, spec->size);
334
335 /* Get the parent process id (we're the parent of the audio thread) */
336 parent = getpid();
337
338 /* We're ready to rock and roll. :-) */
339 return(0);
340 }
341