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