sndout_oss.c 2.1 KB

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  1. /* sound output via OSS */
  2. #include <stdio.h>
  3. #include <sys/types.h>
  4. #include <sys/stat.h>
  5. #include <fcntl.h>
  6. #include <sys/ioctl.h>
  7. #include <sys/soundcard.h>
  8. #include <unistd.h>
  9. #include "sndout_oss.h"
  10. static int sounddev = -1, mixerdev = -1;
  11. int sndout_oss_init(void)
  12. {
  13. if (mixerdev >= 0) close(mixerdev);
  14. mixerdev = open("/dev/mixer", O_RDWR);
  15. if (mixerdev == -1)
  16. {
  17. perror("open(\"/dev/mixer\")");
  18. }
  19. return 0;
  20. }
  21. int sndout_oss_start(int rate, int bits, int stereo)
  22. {
  23. static int s_oldrate = 0, s_oldbits = 0, s_oldstereo = 0;
  24. int frag = 0, bsize, buffers, ret;
  25. // if no settings change, we don't need to do anything,
  26. // since audio is never stopped
  27. if (rate == s_oldrate && s_oldbits == bits && s_oldstereo == stereo)
  28. return 0;
  29. if (sounddev >= 0) close(sounddev);
  30. sounddev = open("/dev/dsp", O_WRONLY|O_ASYNC);
  31. if (sounddev == -1)
  32. {
  33. perror("open(\"/dev/dsp\")");
  34. return -1;
  35. }
  36. // calculate buffer size
  37. // this is tuned for GP2X
  38. buffers = 16;
  39. bsize = rate / 32;
  40. if (rate > 22050) { bsize*=4; buffers*=2; }
  41. while ((bsize>>=1)) frag++;
  42. frag |= buffers<<16; // 16 buffers
  43. ret = ioctl(sounddev, SNDCTL_DSP_SETFRAGMENT, &frag);
  44. if (ret) perror("SNDCTL_DSP_SETFRAGMENT failed");
  45. ret = ioctl(sounddev, SNDCTL_DSP_STEREO, &stereo);
  46. ret |= ioctl(sounddev, SNDCTL_DSP_SETFMT, &bits);
  47. ret |= ioctl(sounddev, SNDCTL_DSP_SPEED, &rate);
  48. if (ret) printf("failed to set audio format\n");
  49. usleep(192*1024);
  50. printf("gp2x_set_sound: %i/%ibit/%s, %i buffers of %i bytes\n",
  51. rate, bits, stereo?"stereo":"mono", frag>>16, 1<<(frag&0xffff));
  52. s_oldrate = rate; s_oldbits = bits; s_oldstereo = stereo;
  53. return 0;
  54. }
  55. int sndout_oss_write(const void *buff, int len)
  56. {
  57. return write(sounddev, buff, len);
  58. }
  59. void sndout_oss_sync(void)
  60. {
  61. ioctl(sounddev, SOUND_PCM_SYNC, 0);
  62. }
  63. void sndout_oss_setvol(int l, int r)
  64. {
  65. if (mixerdev < 0) return;
  66. l=l<0?0:l; l=l>255?255:l; r=r<0?0:r; r=r>255?255:r;
  67. l<<=8; l|=r;
  68. ioctl(mixerdev, SOUND_MIXER_WRITE_PCM, &l); /*SOUND_MIXER_WRITE_VOLUME*/
  69. }
  70. void sndout_oss_exit(void)
  71. {
  72. if (sounddev >= 0) close(sounddev); sounddev = -1;
  73. if (mixerdev >= 0) close(mixerdev); mixerdev = -1;
  74. }