src/audio/arts/SDL_artsaudio.c
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FUNCTIONS
This source file includes following functions.
- Audio_Available
- Audio_DeleteDevice
- Audio_CreateDevice
- ARTSC_WaitAudio
- ARTSC_PlayAudio
- ARTSC_GetAudioBuf
- ARTSC_CloseAudio
- ARTSC_OpenAudio
1 /*
2 SDL - Simple DirectMedia Layer
3 Copyright (C) 1997, 1998, 1999, 2000, 2001 Sam Lantinga
4
5 This library is free software; you can redistribute it and/or
6 modify it under the terms of the GNU Library General Public
7 License as published by the Free Software Foundation; either
8 version 2 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 Library General Public License for more details.
14
15 You should have received a copy of the GNU Library General Public
16 License along with this library; if not, write to the Free
17 Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
18
19 Sam Lantinga
20 slouken@devolution.com
21 */
22
23 #ifdef SAVE_RCSID
24 static char rcsid =
25 "@(#) $Id: SDL_artsaudio.c,v 1.1.2.6 2001/02/28 12:06:11 hercules Exp $";
26 #endif
27
28 /* Allow access to a raw mixing buffer */
29
30 #include <sys/types.h>
31 #include <stdlib.h>
32 #include <stdio.h>
33 #include <string.h>
34 #include <errno.h>
35 #include <signal.h>
36 #include <unistd.h>
37
38 #include "SDL_audio.h"
39 #include "SDL_error.h"
40 #include "SDL_audiomem.h"
41 #include "SDL_audio_c.h"
42 #include "SDL_timer.h"
43 #include "SDL_audiodev_c.h"
44 #include "SDL_artsaudio.h"
45
46 /* The tag name used by artsc audio */
47 #define ARTSC_DRIVER_NAME "artsc"
48
49 /* Audio driver functions */
50 static int ARTSC_OpenAudio(_THIS, SDL_AudioSpec *spec);
51 static void ARTSC_WaitAudio(_THIS);
52 static void ARTSC_PlayAudio(_THIS);
53 static Uint8 *ARTSC_GetAudioBuf(_THIS);
54 static void ARTSC_CloseAudio(_THIS);
55
56 /* Audio driver bootstrap functions */
57
58 static int Audio_Available(void)
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59 {
60 if(arts_init())
61 return 0;
62 else
63 return 1;
64 }
65
66 static void Audio_DeleteDevice(SDL_AudioDevice *device)
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67 {
68 free(device->hidden);
69 free(device);
70 }
71
72 static SDL_AudioDevice *Audio_CreateDevice(int devindex)
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73 {
74 SDL_AudioDevice *this;
75
76 /* Initialize all variables that we clean on shutdown */
77 this = (SDL_AudioDevice *)malloc(sizeof(SDL_AudioDevice));
78 if ( this ) {
79 memset(this, 0, (sizeof *this));
80 this->hidden = (struct SDL_PrivateAudioData *)
81 malloc((sizeof *this->hidden));
82 }
83 if ( (this == NULL) || (this->hidden == NULL) ) {
84 SDL_OutOfMemory();
85 if ( this ) {
86 free(this);
87 }
88 return(0);
89 }
90 memset(this->hidden, 0, (sizeof *this->hidden));
91 stream = 0;
92
93 /* Set the function pointers */
94 this->OpenAudio = ARTSC_OpenAudio;
95 this->WaitAudio = ARTSC_WaitAudio;
96 this->PlayAudio = ARTSC_PlayAudio;
97 this->GetAudioBuf = ARTSC_GetAudioBuf;
98 this->CloseAudio = ARTSC_CloseAudio;
99
100 this->free = Audio_DeleteDevice;
101
102 return this;
103 }
104
105 AudioBootStrap ARTSC_bootstrap = {
106 ARTSC_DRIVER_NAME, "Analog Realtime Synthesizer",
107 Audio_Available, Audio_CreateDevice
108 };
109
110 /* This function waits until it is possible to write a full sound buffer */
111 static void ARTSC_WaitAudio(_THIS)
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112 {
113 Sint32 ticks;
114
115 /* Check to see if the thread-parent process is still alive */
116 { static int cnt = 0;
117 /* Note that this only works with thread implementations
118 that use a different process id for each thread.
119 */
120 if (parent && (((++cnt)%10) == 0)) { /* Check every 10 loops */
121 if ( kill(parent, 0) < 0 ) {
122 this->enabled = 0;
123 }
124 }
125 }
126
127 /* Use timer for general audio synchronization */
128 ticks = ((Sint32)(next_frame - SDL_GetTicks()))-FUDGE_TICKS;
129 if ( ticks > 0 ) {
130 SDL_Delay(ticks);
131 }
132 }
133
134 static void ARTSC_PlayAudio(_THIS)
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135 {
136 int written;
137
138 /* Write the audio data */
139 written = arts_write(stream, mixbuf, mixlen);
140
141 /* If timer synchronization is enabled, set the next write frame */
142 if ( frame_ticks ) {
143 next_frame += frame_ticks;
144 }
145
146 /* If we couldn't write, assume fatal error for now */
147 if ( written < 0 ) {
148 this->enabled = 0;
149 }
150 #ifdef DEBUG_AUDIO
151 fprintf(stderr, "Wrote %d bytes of audio data\n", written);
152 #endif
153 }
154
155 static Uint8 *ARTSC_GetAudioBuf(_THIS)
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156 {
157 return(mixbuf);
158 }
159
160 static void ARTSC_CloseAudio(_THIS)
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161 {
162 if ( mixbuf != NULL ) {
163 SDL_FreeAudioMem(mixbuf);
164 mixbuf = NULL;
165 }
166 if ( stream ) {
167 arts_close_stream(stream);
168 stream = 0;
169 }
170 }
171
172 static int ARTSC_OpenAudio(_THIS, SDL_AudioSpec *spec)
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173 {
174 int bits, frag_spec;
175 Uint16 test_format, format;
176
177 /* Reset the timer synchronization flag */
178 frame_ticks = 0.0;
179
180 mixbuf = NULL;
181
182 /* Try for a closest match on audio format */
183 format = 0;
184 bits = 0;
185 for ( test_format = SDL_FirstAudioFormat(spec->format);
186 ! format && test_format; ) {
187 #ifdef DEBUG_AUDIO
188 fprintf(stderr, "Trying format 0x%4.4x\n", test_format);
189 #endif
190 switch ( test_format ) {
191 case AUDIO_U8:
192 bits = 8;
193 format = 1;
194 break;
195 case AUDIO_S16LSB:
196 bits = 16;
197 format = 1;
198 break;
199 default:
200 format = 0;
201 break;
202 }
203 if ( ! format ) {
204 test_format = SDL_NextAudioFormat();
205 }
206 }
207 if ( format == 0 ) {
208 SDL_SetError("Couldn't find any hardware audio formats");
209 return(-1);
210 }
211 spec->format = test_format;
212
213 stream = arts_play_stream(spec->freq, bits, spec->channels, "SDL");
214
215 /* Calculate the final parameters for this audio specification */
216 SDL_CalculateAudioSpec(spec);
217
218 /* Determine the power of two of the fragment size */
219 for ( frag_spec = 0; (0x01<<frag_spec) < spec->size; ++frag_spec );
220 if ( (0x01<<frag_spec) != spec->size ) {
221 SDL_SetError("Fragment size must be a power of two");
222 return(-1);
223 }
224 frag_spec |= 0x00020000; /* two fragments, for low latency */
225
226 #ifdef ARTS_P_PACKET_SETTINGS
227 arts_stream_set(stream, ARTS_P_PACKET_SETTINGS, frag_spec);
228 #else
229 arts_stream_set(stream, ARTS_P_PACKET_SIZE, frag_spec&0xffff);
230 arts_stream_set(stream, ARTS_P_PACKET_COUNT, frag_spec>>16);
231 #endif
232 spec->size = arts_stream_get(stream, ARTS_P_PACKET_SIZE);
233
234 /* Allocate mixing buffer */
235 mixlen = spec->size;
236 mixbuf = (Uint8 *)SDL_AllocAudioMem(mixlen);
237 if ( mixbuf == NULL ) {
238 return(-1);
239 }
240 memset(mixbuf, spec->silence, spec->size);
241
242 /* Get the parent process id (we're the parent of the audio thread) */
243 parent = getpid();
244
245 /* We're ready to rock and roll. :-) */
246 return(0);
247 }