ALgetfd(3dm)

NAME
     ALgetfd - (obsolete) get the file descriptor for an audio port

SYNOPSIS
     #include <dmedia/audio.h>

     int ALgetfd(ALport port)

PARAMETER
     port   expects the ALport structure whose file descriptor you desire.
            This structure is the returned value of an ALopenport(3dm) call.

DESCRIPTION
     ALgetfd is obsolete and is provided for backward compatibility. The
     preferred function is alGetFD(3dm).

     ALgetfd() returns a file descriptor that you can use to construct the
     arguments to a select(2)  or poll(2) call. These calls are used when you
     want to give up control of the CPU (letting other processes use the CPU)
     until the device fills/empties the audio port buffer past the fillpoint.
     At that time, select(2) and poll(2) return, and your code can continue
     processing the audio ports.  If the device has already filled/emptied the
     audio port buffer past the fillpoint when you make the call, control
     returns to your program immediately.

     When using select(2), an input port's file descriptor is used in a read
     fdset and an output port's file descriptor is used in a write fdset.

     When using poll(2), an input port's file descriptor is used with the
     POLLIN event flag and an output port's file descriptor is used with a
     POLLOUT event flag.

     Several AL functions implicitly change the current fillpoint value.
     Therefore, ALsetfillpoint(3dm) must be called immediately before a
     select(2) or poll(2) call which uses an audio file descriptor.

     ALgetfd(3dm) can fail for the following reason:

     AL_BAD_PORT   port is either invalid or null.

DIAGNOSTICS
     Upon successful completion, ALgetfd(3dm) returns a valid file descriptor.
     Otherwise, ALgetfd(3dm) returns -1 and sets an error number which can be
     retrieved with oserror(3C).

SEE ALSO
     ALsetfillpoint(3dm), ALgetfillpoint(3dm), ALopenport(3dm), select(2),
     poll(2), oserror(3C)