| | Open Sound System |
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ioctl(fd, SNDCTL_DSP_SETDUPLEX, NULL);
The above code fragment lacks all error checks for clarity. Real world applications must always check for the errors and handle them as described below. Also most OSS ioctl calls will return information in the argument variable and it's usually necessary to check it too.
Do not use this ioctl call any more. It was necessary with some ancient sound cards in dark 90's but has not been implemented after that. This call has no efect.
Please look at the When OSS audio ioctl calls can be made section for information about DSP ioctl call ordering.
The return value from the OSS ioctl calls will be -1 if a fatal error occurred. Other values mean that the ioctl call was more or less successful. However in most cases the application must check the value returned in the argument to see what was the accepted value.
Please see the Possible error codes (errno) returned by OSS calls section for more info about the error codes returned by OSS.
| fulldup.c | Full duplex sample program using the single device approach. |