A lot of thanks for anyone's comments.

aka j,

Unfortunatly I am not so familiar with assembler of a uCU
that using. But your positive results in assembler give me
a hope to get it in C too.

As to variable block length, it is not going to be as
variable since a s_ptr could be used to link to a proper
menu string instead of the actual string inside of structure.
My problem is to unify activated functions. The functions
should return the same types and to have the same signatures,
but actually it is not so. It may be useful to integrate the
linked list(s) technicue with machine state one.

Sorry, not clear what do you mean "hard coding"? Is that using
some constant address values instead of values that could be
calculated by linker from function/structure identifiers?
If so, it's clear. Even more, I do not see any way right now
to perform the "hard coding" in C.

Thank you!
Best regards,
Oleg