Writing Linked-in drivers that also work on Enea OSE is very similar for how you would do it for Unix. The difference from Unix is that driver_select, ready_input and ready_output all work with signals instead of file descriptors. This means that the driver_select is used to specify which type of signal should trigger calls to ready_input/ready_output. The functions described below are available to driver programmers on Enea OSE to facilitate this.
ErlDrvEventis a handle to a signal number and id combination. It is passed to driver_select(3).
union SIGNAL * erl_drv_ose_get_signal(ErlDrvEvent drv_event)
Fetch the next signal associated with
Signals will be returned in the order which they were received and
when no more signals are available
NULL will be returned.
Use this function in the ready_input/ready_output callbacks
to get signals.
ErlDrvEvent erl_drv_ose_event_alloc(SIGSELECT signo, ErlDrvOseEventId id, ErlDrvOseEventId (*resolve_signal)(union SIGNAL* sig), void *extra)
Create a new
ErlDrvEvent associated with
id and uses the
resolve_signal function to extract
id from a signal with
parameter can be used for additional data. See
Signals in a Linked-in driver in the OSE User's Guide.
void erl_drv_ose_event_free(ErlDrvEvent drv_event)
ErlDrvEvent. This should always be done in the
callback when the event is no longer being used.
void erl_drv_ose_event_fetch(ErlDrvEvent drv_event, SIGSELECT *signo, ErlDrvOseEventId *id, void **extra)
Write the signal number, id and any extra data associated with
NULL can be
also passed as
id in order to ignore that field.