If you need to reassign EVM events after they are created,
received, or read, you must know how an event is held in memory.
The EvmEvent_t type defines a pointer to
a short handle structure that holds some control information and
a pointer to the event body. When you use EvmEventCreate() or any related function to create a new event, the following
functions are performed:
Allocates heap
memory separately for the handle and the event body
Stores the address of the event body in the handle
Returns the address of the handle as the function's EvmEvent_t output
argument
You must use the returned pointer any time you need to refer
to the event.
If you modify the event by adding a variable, for example, it
is likely that the space used by the event body may be freed and
reallocated in a new location. If this happens, the address stored
in the handle is automatically updated to reflect the new location.
As a result, the reallocation is completely transparent to your
program. The location of the handle remains unchanged for the life
of the event.
If you need to transfer an event from one variable to another,
you can use a simple C-language assignment statement between variables
of type EvmEvent_t. Because the value you hold
is simply a pointer to a constant location — the event's
handle — you can continue to use both of the variables
to refer to the event. However, if you subsequently use EvmEventDestroy() to destroy the event, you must discard both references.
Reassigning an event copies only the reference to its handle;
it does not copy the event body. If you need to make a completely
independent copy of the event, use the EvmEventDup() function call.
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