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0
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1 /*
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2 SDL - Simple DirectMedia Layer
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3 Copyright (C) 1997, 1998, 1999, 2000, 2001 Sam Lantinga
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4
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5 This library is free software; you can redistribute it and/or
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6 modify it under the terms of the GNU Library General Public
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7 License as published by the Free Software Foundation; either
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8 version 2 of the License, or (at your option) any later version.
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9
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10 This library is distributed in the hope that it will be useful,
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11 but WITHOUT ANY WARRANTY; without even the implied warranty of
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12 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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13 Library General Public License for more details.
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14
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15 You should have received a copy of the GNU Library General Public
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16 License along with this library; if not, write to the Free
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17 Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
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18
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19 Sam Lantinga
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20 slouken@devolution.com
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21 */
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22
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23 #ifdef SAVE_RCSID
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24 static char rcsid =
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25 "@(#) $Id$";
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26 #endif
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27
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28 /* Allow access to a raw mixing buffer */
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29
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30 #include <stdlib.h>
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31 #include <stdio.h>
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32 #include <string.h>
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33 #include <errno.h>
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34 #include <unistd.h>
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35 #include <fcntl.h>
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36 #include <signal.h>
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37 #include <sys/time.h>
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38 #include <sys/ioctl.h>
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39 #include <sys/stat.h>
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40 #include <sys/soundcard.h>
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41
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42 #include "SDL_audio.h"
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43 #include "SDL_error.h"
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44 #include "SDL_audiomem.h"
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45 #include "SDL_audio_c.h"
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46 #include "SDL_timer.h"
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47 #include "SDL_audiodev_c.h"
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48 #include "SDL_dspaudio.h"
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49
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50 /* The tag name used by DSP audio */
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51 #define DSP_DRIVER_NAME "dsp"
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52
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53 /* Open the audio device for playback, and don't block if busy */
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54 /*#define USE_BLOCKING_WRITES*/
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55 #ifdef USE_BLOCKING_WRITES
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56 #define OPEN_FLAGS O_WRONLY
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57 #else
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58 #define OPEN_FLAGS (O_WRONLY|O_NONBLOCK)
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59 #endif
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60
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61 /* Audio driver functions */
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62 static int DSP_OpenAudio(_THIS, SDL_AudioSpec *spec);
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63 static void DSP_WaitAudio(_THIS);
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64 static void DSP_PlayAudio(_THIS);
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65 static Uint8 *DSP_GetAudioBuf(_THIS);
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66 static void DSP_CloseAudio(_THIS);
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67
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68 /* Audio driver bootstrap functions */
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69
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70 static int Audio_Available(void)
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71 {
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72 int fd;
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73 int available;
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74
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75 available = 0;
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76 fd = SDL_OpenAudioPath(NULL, 0, OPEN_FLAGS, 0);
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77 if ( fd >= 0 ) {
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78 available = 1;
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79 close(fd);
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80 }
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81 return(available);
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82 }
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83
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84 static void Audio_DeleteDevice(SDL_AudioDevice *device)
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85 {
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86 free(device->hidden);
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87 free(device);
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88 }
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89
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90 static SDL_AudioDevice *Audio_CreateDevice(int devindex)
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91 {
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92 SDL_AudioDevice *this;
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93
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94 /* Initialize all variables that we clean on shutdown */
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95 this = (SDL_AudioDevice *)malloc(sizeof(SDL_AudioDevice));
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96 if ( this ) {
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97 memset(this, 0, (sizeof *this));
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98 this->hidden = (struct SDL_PrivateAudioData *)
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99 malloc((sizeof *this->hidden));
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100 }
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101 if ( (this == NULL) || (this->hidden == NULL) ) {
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102 SDL_OutOfMemory();
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103 if ( this ) {
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104 free(this);
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105 }
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106 return(0);
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107 }
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108 memset(this->hidden, 0, (sizeof *this->hidden));
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109 audio_fd = -1;
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110
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111 /* Set the function pointers */
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112 this->OpenAudio = DSP_OpenAudio;
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113 this->WaitAudio = DSP_WaitAudio;
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114 this->PlayAudio = DSP_PlayAudio;
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115 this->GetAudioBuf = DSP_GetAudioBuf;
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116 this->CloseAudio = DSP_CloseAudio;
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117
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118 this->free = Audio_DeleteDevice;
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119
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120 return this;
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121 }
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122
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123 AudioBootStrap DSP_bootstrap = {
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124 DSP_DRIVER_NAME, "OSS /dev/dsp standard audio",
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125 Audio_Available, Audio_CreateDevice
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126 };
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127
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128 /* This function waits until it is possible to write a full sound buffer */
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129 static void DSP_WaitAudio(_THIS)
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130 {
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131 #ifndef USE_BLOCKING_WRITES /* Not necessary because of blocking writes */
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132 fd_set fdset;
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133
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134 /* Check to see if the thread-parent process is still alive */
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135 { static int cnt = 0;
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136 /* Note that this only works with thread implementations
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137 that use a different process id for each thread.
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138 */
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139 if (parent && (((++cnt)%10) == 0)) { /* Check every 10 loops */
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140 if ( kill(parent, 0) < 0 ) {
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141 this->enabled = 0;
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142 }
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143 }
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144 }
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145
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146 /* See if we need to use timed audio synchronization */
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147 if ( frame_ticks ) {
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148 /* Use timer for general audio synchronization */
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149 Sint32 ticks;
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150
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151 ticks = ((Sint32)(next_frame - SDL_GetTicks()))-FUDGE_TICKS;
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152 if ( ticks > 0 ) {
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153 SDL_Delay(ticks);
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154 }
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155 } else {
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156 /* Use select() for audio synchronization */
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157 struct timeval timeout;
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158 FD_ZERO(&fdset);
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159 FD_SET(audio_fd, &fdset);
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160 timeout.tv_sec = 10;
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161 timeout.tv_usec = 0;
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162 #ifdef DEBUG_AUDIO
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163 fprintf(stderr, "Waiting for audio to get ready\n");
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164 #endif
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165 if ( select(audio_fd+1, NULL, &fdset, NULL, &timeout) <= 0 ) {
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166 const char *message =
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167 "Audio timeout - buggy audio driver? (disabled)";
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168 /* In general we should never print to the screen,
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169 but in this case we have no other way of letting
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170 the user know what happened.
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171 */
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172 fprintf(stderr, "SDL: %s\n", message);
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173 this->enabled = 0;
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174 /* Don't try to close - may hang */
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175 audio_fd = -1;
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176 #ifdef DEBUG_AUDIO
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177 fprintf(stderr, "Done disabling audio\n");
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178 #endif
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179 }
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180 #ifdef DEBUG_AUDIO
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181 fprintf(stderr, "Ready!\n");
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182 #endif
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183 }
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184 #endif /* !USE_BLOCKING_WRITES */
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185 }
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186
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187 static void DSP_PlayAudio(_THIS)
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188 {
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189 int written;
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190
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191 /* Write the audio data, checking for EAGAIN on broken audio drivers */
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192 do {
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193 written = write(audio_fd, mixbuf, mixlen);
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194 if ( (written < 0) && ((errno == 0) || (errno == EAGAIN)) ) {
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195 SDL_Delay(1); /* Let a little CPU time go by */
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196 }
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197 } while ( (written < 0) &&
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198 ((errno == 0) || (errno == EAGAIN) || (errno == EINTR)) );
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199
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200 /* If timer synchronization is enabled, set the next write frame */
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201 if ( frame_ticks ) {
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202 next_frame += frame_ticks;
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203 }
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204
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205 /* If we couldn't write, assume fatal error for now */
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206 if ( written < 0 ) {
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207 this->enabled = 0;
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208 }
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209 #ifdef DEBUG_AUDIO
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210 fprintf(stderr, "Wrote %d bytes of audio data\n", written);
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211 #endif
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212 }
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213
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214 static Uint8 *DSP_GetAudioBuf(_THIS)
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215 {
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216 return(mixbuf);
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217 }
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218
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219 static void DSP_CloseAudio(_THIS)
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220 {
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221 if ( mixbuf != NULL ) {
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222 SDL_FreeAudioMem(mixbuf);
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223 mixbuf = NULL;
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224 }
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225 if ( audio_fd >= 0 ) {
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226 close(audio_fd);
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227 audio_fd = -1;
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228 }
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229 }
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230
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231 static int DSP_ReopenAudio(_THIS, const char *audiodev, int format,
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232 SDL_AudioSpec *spec)
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233 {
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234 int frag_spec;
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235 int value;
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236
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237 /* Close and then reopen the audio device */
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238 close(audio_fd);
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239 audio_fd = open(audiodev, O_WRONLY, 0);
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240 if ( audio_fd < 0 ) {
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241 SDL_SetError("Couldn't open %s: %s", audiodev, strerror(errno));
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242 return(-1);
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243 }
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244
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245 /* Calculate the final parameters for this audio specification */
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246 SDL_CalculateAudioSpec(spec);
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247
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248 /* Determine the power of two of the fragment size */
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249 for ( frag_spec = 0; (0x01<<frag_spec) < spec->size; ++frag_spec );
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250 if ( (0x01<<frag_spec) != spec->size ) {
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251 SDL_SetError("Fragment size must be a power of two");
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252 return(-1);
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253 }
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254 frag_spec |= 0x00020000; /* two fragments, for low latency */
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255
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256 /* Set the audio buffering parameters */
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257 #ifdef DEBUG_AUDIO
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258 fprintf(stderr, "Requesting %d fragments of size %d\n",
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259 (frag_spec >> 16), 1<<(frag_spec&0xFFFF));
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260 #endif
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261 if ( ioctl(audio_fd, SNDCTL_DSP_SETFRAGMENT, &frag_spec) < 0 ) {
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262 fprintf(stderr, "Warning: Couldn't set audio fragment size\n");
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263 }
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264 #ifdef DEBUG_AUDIO
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265 { audio_buf_info info;
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266 ioctl(audio_fd, SNDCTL_DSP_GETOSPACE, &info);
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267 fprintf(stderr, "fragments = %d\n", info.fragments);
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268 fprintf(stderr, "fragstotal = %d\n", info.fragstotal);
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269 fprintf(stderr, "fragsize = %d\n", info.fragsize);
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270 fprintf(stderr, "bytes = %d\n", info.bytes);
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271 }
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272 #endif
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273
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274 /* Set the audio format */
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275 value = format;
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276 if ( (ioctl(audio_fd, SNDCTL_DSP_SETFMT, &value) < 0) ||
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277 (value != format) ) {
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278 SDL_SetError("Couldn't set audio format");
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279 return(-1);
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280 }
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281
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282 /* Set the number of channels of output */
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283 value = spec->channels;
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284 #ifdef SNDCTL_DSP_CHANNELS
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285 if ( ioctl(audio_fd, SNDCTL_DSP_CHANNELS, &value) < 0 ) {
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286 #endif
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287 value = (spec->channels > 1);
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288 ioctl(audio_fd, SNDCTL_DSP_STEREO, &value);
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289 value = (value ? 2 : 1);
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290 #ifdef SNDCTL_DSP_CHANNELS
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291 }
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292 #endif
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293 if ( value != spec->channels ) {
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294 SDL_SetError("Couldn't set audio channels");
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295 return(-1);
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296 }
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297
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298 /* Set the DSP frequency */
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299 value = spec->freq;
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300 if ( ioctl(audio_fd, SOUND_PCM_WRITE_RATE, &value) < 0 ) {
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301 SDL_SetError("Couldn't set audio frequency");
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302 return(-1);
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303 }
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304 spec->freq = value;
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305
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306 /* We successfully re-opened the audio */
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307 return(0);
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308 }
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309
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310 static int DSP_OpenAudio(_THIS, SDL_AudioSpec *spec)
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311 {
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312 char audiodev[1024];
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313 int format;
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314 int value;
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315 Uint16 test_format;
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316
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317 /* Reset the timer synchronization flag */
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318 frame_ticks = 0.0;
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319
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320 /* Open the audio device */
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321 audio_fd = SDL_OpenAudioPath(audiodev, sizeof(audiodev), OPEN_FLAGS, 0);
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322 if ( audio_fd < 0 ) {
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323 SDL_SetError("Couldn't open %s: %s", audiodev, strerror(errno));
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324 return(-1);
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325 }
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326 mixbuf = NULL;
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327
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328 /* Get a list of supported hardware formats */
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329 if ( ioctl(audio_fd, SNDCTL_DSP_GETFMTS, &value) < 0 ) {
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330 SDL_SetError("Couldn't get audio format list");
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331 return(-1);
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332 }
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333
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334 /* Try for a closest match on audio format */
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335 format = 0;
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336 for ( test_format = SDL_FirstAudioFormat(spec->format);
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337 ! format && test_format; ) {
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338 #ifdef DEBUG_AUDIO
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339 fprintf(stderr, "Trying format 0x%4.4x\n", test_format);
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340 #endif
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341 switch ( test_format ) {
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342 case AUDIO_U8:
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343 if ( value & AFMT_U8 ) {
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344 format = AFMT_U8;
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345 }
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346 break;
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347 case AUDIO_S8:
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348 if ( value & AFMT_S8 ) {
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349 format = AFMT_S8;
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350 }
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351 break;
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352 case AUDIO_S16LSB:
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353 if ( value & AFMT_S16_LE ) {
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354 format = AFMT_S16_LE;
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355 }
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356 break;
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357 case AUDIO_S16MSB:
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358 if ( value & AFMT_S16_BE ) {
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359 format = AFMT_S16_BE;
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360 }
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361 break;
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362 case AUDIO_U16LSB:
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363 if ( value & AFMT_U16_LE ) {
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364 format = AFMT_U16_LE;
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365 }
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366 break;
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367 case AUDIO_U16MSB:
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368 if ( value & AFMT_U16_BE ) {
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369 format = AFMT_U16_BE;
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370 }
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371 break;
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372 default:
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373 break;
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374 }
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375 if ( ! format ) {
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376 test_format = SDL_NextAudioFormat();
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377 }
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378 }
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379 if ( format == 0 ) {
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380 SDL_SetError("Couldn't find any hardware audio formats");
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381 return(-1);
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382 }
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383 spec->format = test_format;
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384
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385 /* Set the audio format */
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386 value = format;
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387 if ( (ioctl(audio_fd, SNDCTL_DSP_SETFMT, &value) < 0) ||
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388 (value != format) ) {
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389 SDL_SetError("Couldn't set audio format");
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390 return(-1);
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391 }
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392
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393 /* Set the number of channels of output */
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394 value = spec->channels;
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395 #ifdef SNDCTL_DSP_CHANNELS
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396 if ( ioctl(audio_fd, SNDCTL_DSP_CHANNELS, &value) < 0 ) {
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397 #endif
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398 value = (spec->channels > 1);
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399 ioctl(audio_fd, SNDCTL_DSP_STEREO, &value);
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400 value = (value ? 2 : 1);
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401 #ifdef SNDCTL_DSP_CHANNELS
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402 }
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403 #endif
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404 spec->channels = value;
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405
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406 /* Because some drivers don't allow setting the buffer size
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407 after setting the format, we must re-open the audio device
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408 once we know what format and channels are supported
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409 */
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410 if ( DSP_ReopenAudio(this, audiodev, format, spec) < 0 ) {
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411 /* Error is set by DSP_ReopenAudio() */
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412 return(-1);
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413 }
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414
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415 /* Allocate mixing buffer */
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416 mixlen = spec->size;
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417 mixbuf = (Uint8 *)SDL_AllocAudioMem(mixlen);
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418 if ( mixbuf == NULL ) {
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419 return(-1);
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420 }
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421 memset(mixbuf, spec->silence, spec->size);
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422
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423 #ifndef USE_BLOCKING_WRITES
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424 /* Check to see if we need to use select() workaround */
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425 { char *workaround;
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426 workaround = getenv("SDL_DSP_NOSELECT");
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427 if ( workaround ) {
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428 frame_ticks = (float)(spec->samples*1000)/spec->freq;
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429 next_frame = SDL_GetTicks()+frame_ticks;
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430 }
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431 }
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432 #endif /* !USE_BLOCKING_WRITES */
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433
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434 /* Get the parent process id (we're the parent of the audio thread) */
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435 parent = getpid();
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436
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437 /* We're ready to rock and roll. :-) */
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438 return(0);
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439 }
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