Question

I have the following code, which works fine and has been in use for a quite a while now… but I have no idea what it means.

struct event_param
{
    int task:3;
    int param1;
    int param2;
};

#define SV_DRIVER_EVENTS_MASK_SIZE (SV_DRIVER_EVENT_LAST*sizeof(struct event_param))
typedef struct event_param driver_event_mask[SV_DRIVER_EVENTS_MASK_SIZE];
typedef driver_event_mask DriverEventMask;

• What does driver_event_mask represent?
• Why is there sizeof(struct event_param) inside the array?

Answer 1

how to typedef strcuts array in c?

How to define is already shown in your question, for why refer below:-

If a typedef name denotes a variable length array type, the length of
the array is fixed at the time the typedef name is defined, not each
time it is used:

what does DriverEventMask represents

DriverEventMask represent struct event_param

why there are sizeof(struct event_param)

So that SV_DRIVER_EVENTS_MASK_SIZE will represent the size of struct
event_param. This struct contain bit fields and the way it is arranged
is not sure until we know if there are any compiler directives to
avoid padding.