Atlas - SDL_dspaudio.c
Home / ext / SDL2 / src / audio / dsp Lines: 8 | Size: 9394 bytes [Download] [Show on GitHub] [Search similar files] [Raw] [Raw (proxy)][FILE BEGIN]1/* 2 Simple DirectMedia Layer 3 Copyright (C) 1997-2018 Sam Lantinga <[email protected]> 4 5 This software is provided 'as-is', without any express or implied 6 warranty. In no event will the authors be held liable for any damages 7 arising from the use of this software. 8 9 Permission is granted to anyone to use this software for any purpose, 10 including commercial applications, and to alter it and redistribute it 11 freely, subject to the following restrictions: 12 13 1. The origin of this software must not be misrepresented; you must not 14 claim that you wrote the original software. If you use this software 15 in a product, an acknowledgment in the product documentation would be 16 appreciated but is not required. 17 2. Altered source versions must be plainly marked as such, and must not be 18 misrepresented as being the original software. 19 3. This notice may not be removed or altered from any source distribution. 20*/ 21#include "../../SDL_internal.h" 22 23#if SDL_AUDIO_DRIVER_OSS 24 25/* Allow access to a raw mixing buffer */ 26 27#include <stdio.h> /* For perror() */ 28#include <string.h> /* For strerror() */ 29#include <errno.h> 30#include <unistd.h> 31#include <fcntl.h> 32#include <signal.h> 33#include <sys/time.h> 34#include <sys/ioctl.h> 35#include <sys/stat.h> 36 37#if SDL_AUDIO_DRIVER_OSS_SOUNDCARD_H 38/* This is installed on some systems */ 39#include <soundcard.h> 40#else 41/* This is recommended by OSS */ 42#include <sys/soundcard.h> 43#endif 44 45#include "SDL_timer.h" 46#include "SDL_audio.h" 47#include "../SDL_audio_c.h" 48#include "../SDL_audiodev_c.h" 49#include "SDL_dspaudio.h" 50 51 52static void 53DSP_DetectDevices(void) 54{ 55 SDL_EnumUnixAudioDevices(0, NULL); 56} 57 58 59static void 60DSP_CloseDevice(_THIS) 61{ 62 if (this->hidden->audio_fd >= 0) { 63 close(this->hidden->audio_fd); 64 } 65 SDL_free(this->hidden->mixbuf); 66 SDL_free(this->hidden); 67} 68 69 70static int 71DSP_OpenDevice(_THIS, void *handle, const char *devname, int iscapture) 72{ 73 const int flags = ((iscapture) ? OPEN_FLAGS_INPUT : OPEN_FLAGS_OUTPUT); 74 int format; 75 int value; 76 int frag_spec; 77 SDL_AudioFormat test_format; 78 79 /* We don't care what the devname is...we'll try to open anything. */ 80 /* ...but default to first name in the list... */ 81 if (devname == NULL) { 82 devname = SDL_GetAudioDeviceName(0, iscapture); 83 if (devname == NULL) { 84 return SDL_SetError("No such audio device"); 85 } 86 } 87 88 /* Make sure fragment size stays a power of 2, or OSS fails. */ 89 /* I don't know which of these are actually legal values, though... */ 90 if (this->spec.channels > 8) 91 this->spec.channels = 8; 92 else if (this->spec.channels > 4) 93 this->spec.channels = 4; 94 else if (this->spec.channels > 2) 95 this->spec.channels = 2; 96 97 /* Initialize all variables that we clean on shutdown */ 98 this->hidden = (struct SDL_PrivateAudioData *) 99 SDL_malloc((sizeof *this->hidden)); 100 if (this->hidden == NULL) { 101 return SDL_OutOfMemory(); 102 } 103 SDL_zerop(this->hidden); 104 105 /* Open the audio device */ 106 this->hidden->audio_fd = open(devname, flags, 0); 107 if (this->hidden->audio_fd < 0) { 108 return SDL_SetError("Couldn't open %s: %s", devname, strerror(errno)); 109 } 110 111 /* Make the file descriptor use blocking i/o with fcntl() */ 112 { 113 long ctlflags; 114 ctlflags = fcntl(this->hidden->audio_fd, F_GETFL); 115 ctlflags &= ~O_NONBLOCK; 116 if (fcntl(this->hidden->audio_fd, F_SETFL, ctlflags) < 0) { 117 return SDL_SetError("Couldn't set audio blocking mode"); 118 } 119 } 120 121 /* Get a list of supported hardware formats */ 122 if (ioctl(this->hidden->audio_fd, SNDCTL_DSP_GETFMTS, &value) < 0) { 123 perror("SNDCTL_DSP_GETFMTS"); 124 return SDL_SetError("Couldn't get audio format list"); 125 } 126 127 /* Try for a closest match on audio format */ 128 format = 0; 129 for (test_format = SDL_FirstAudioFormat(this->spec.format); 130 !format && test_format;) { 131#ifdef DEBUG_AUDIO 132 fprintf(stderr, "Trying format 0x%4.4x\n", test_format); 133#endif 134 switch (test_format) { 135 case AUDIO_U8: 136 if (value & AFMT_U8) { 137 format = AFMT_U8; 138 } 139 break; 140 case AUDIO_S16LSB: 141 if (value & AFMT_S16_LE) { 142 format = AFMT_S16_LE; 143 } 144 break; 145 case AUDIO_S16MSB: 146 if (value & AFMT_S16_BE) { 147 format = AFMT_S16_BE; 148 } 149 break; 150#if 0 151/* 152 * These formats are not used by any real life systems so they are not 153 * needed here. 154 */ 155 case AUDIO_S8: 156 if (value & AFMT_S8) { 157 format = AFMT_S8; 158 } 159 break; 160 case AUDIO_U16LSB: 161 if (value & AFMT_U16_LE) { 162 format = AFMT_U16_LE; 163 } 164 break; 165 case AUDIO_U16MSB: 166 if (value & AFMT_U16_BE) { 167 format = AFMT_U16_BE; 168 } 169 break; 170#endif 171 default: 172 format = 0; 173 break; 174 } 175 if (!format) { 176 test_format = SDL_NextAudioFormat(); 177 } 178 } 179 if (format == 0) { 180 return SDL_SetError("Couldn't find any hardware audio formats"); 181 } 182 this->spec.format = test_format; 183 184 /* Set the audio format */ 185 value = format; 186 if ((ioctl(this->hidden->audio_fd, SNDCTL_DSP_SETFMT, &value) < 0) || 187 (value != format)) { 188 perror("SNDCTL_DSP_SETFMT"); 189 return SDL_SetError("Couldn't set audio format"); 190 } 191 192 /* Set the number of channels of output */ 193 value = this->spec.channels; 194 if (ioctl(this->hidden->audio_fd, SNDCTL_DSP_CHANNELS, &value) < 0) { 195 perror("SNDCTL_DSP_CHANNELS"); 196 return SDL_SetError("Cannot set the number of channels"); 197 } 198 this->spec.channels = value; 199 200 /* Set the DSP frequency */ 201 value = this->spec.freq; 202 if (ioctl(this->hidden->audio_fd, SNDCTL_DSP_SPEED, &value) < 0) { 203 perror("SNDCTL_DSP_SPEED"); 204 return SDL_SetError("Couldn't set audio frequency"); 205 } 206 this->spec.freq = value; 207 208 /* Calculate the final parameters for this audio specification */ 209 SDL_CalculateAudioSpec(&this->spec); 210 211 /* Determine the power of two of the fragment size */ 212 for (frag_spec = 0; (0x01U << frag_spec) < this->spec.size; ++frag_spec); 213 if ((0x01U << frag_spec) != this->spec.size) { 214 return SDL_SetError("Fragment size must be a power of two"); 215 } 216 frag_spec |= 0x00020000; /* two fragments, for low latency */ 217 218 /* Set the audio buffering parameters */ 219#ifdef DEBUG_AUDIO 220 fprintf(stderr, "Requesting %d fragments of size %d\n", 221 (frag_spec >> 16), 1 << (frag_spec & 0xFFFF)); 222#endif 223 if (ioctl(this->hidden->audio_fd, SNDCTL_DSP_SETFRAGMENT, &frag_spec) < 0) { 224 perror("SNDCTL_DSP_SETFRAGMENT"); 225 } 226#ifdef DEBUG_AUDIO 227 { 228 audio_buf_info info; 229 ioctl(this->hidden->audio_fd, SNDCTL_DSP_GETOSPACE, &info); 230 fprintf(stderr, "fragments = %d\n", info.fragments); 231 fprintf(stderr, "fragstotal = %d\n", info.fragstotal); 232 fprintf(stderr, "fragsize = %d\n", info.fragsize); 233 fprintf(stderr, "bytes = %d\n", info.bytes); 234 } 235#endif 236 237 /* Allocate mixing buffer */ 238 if (!iscapture) { 239 this->hidden->mixlen = this->spec.size; 240 this->hidden->mixbuf = (Uint8 *) SDL_malloc(this->hidden->mixlen); 241 if (this->hidden->mixbuf == NULL) { 242 return SDL_OutOfMemory(); 243 } 244 SDL_memset(this->hidden->mixbuf, this->spec.silence, this->spec.size); 245 } 246 247 /* We're ready to rock and roll. :-) */ 248 return 0; 249} 250 251 252static void 253DSP_PlayDevice(_THIS) 254{ 255 struct SDL_PrivateAudioData *h = this->hidden; 256 if (write(h->audio_fd, h->mixbuf, h->mixlen) == -1) { 257 perror("Audio write"); 258 SDL_OpenedAudioDeviceDisconnected(this); 259 } 260#ifdef DEBUG_AUDIO 261 fprintf(stderr, "Wrote %d bytes of audio data\n", h->mixlen); 262#endif 263} 264 265static Uint8 * 266DSP_GetDeviceBuf(_THIS) 267{ 268 return (this->hidden->mixbuf); 269} 270 271static int 272DSP_CaptureFromDevice(_THIS, void *buffer, int buflen) 273{ 274 return (int) read(this->hidden->audio_fd, buffer, buflen); 275} 276 277static void 278DSP_FlushCapture(_THIS) 279{ 280 struct SDL_PrivateAudioData *h = this->hidden; 281 audio_buf_info info; 282 if (ioctl(h->audio_fd, SNDCTL_DSP_GETISPACE, &info) == 0) { 283 while (info.bytes > 0) { 284 char buf[512]; 285 const size_t len = SDL_min(sizeof (buf), info.bytes); 286 const ssize_t br = read(h->audio_fd, buf, len); 287 if (br <= 0) { 288 break; 289 } 290 info.bytes -= br; 291 } 292 } 293} 294 295static int 296DSP_Init(SDL_AudioDriverImpl * impl) 297{ 298 /* Set the function pointers */ 299 impl->DetectDevices = DSP_DetectDevices; 300 impl->OpenDevice = DSP_OpenDevice; 301 impl->PlayDevice = DSP_PlayDevice; 302 impl->GetDeviceBuf = DSP_GetDeviceBuf; 303 impl->CloseDevice = DSP_CloseDevice; 304 impl->CaptureFromDevice = DSP_CaptureFromDevice; 305 impl->FlushCapture = DSP_FlushCapture; 306 307 impl->AllowsArbitraryDeviceNames = 1; 308 impl->HasCaptureSupport = SDL_TRUE; 309 310 return 1; /* this audio target is available. */ 311} 312 313 314AudioBootStrap DSP_bootstrap = { 315 "dsp", "OSS /dev/dsp standard audio", DSP_Init, 0 316}; 317 318#endif /* SDL_AUDIO_DRIVER_OSS */ 319 320/* vi: set ts=4 sw=4 expandtab: */ 321[FILE END](C) 2025 0x4248 (C) 2025 4248 Media and 4248 Systems, All part of 0x4248 See LICENCE files for more information. Not all files are by 0x4248 always check Licencing.