check source of trigger

Hello,

I have a question about trigger. I have tables with the following structure:

create table A (  e_codeA char(5) default '' not null,  n_codeA varchar(20) default '' not null,  constraint A_pkey
primarykey ( e_codeA )
 
);

create table B (  e_codeB char(5) default '' not null,  e_codeA char(5) default '' not null     constraint e_codeA_ref
referencesA( e_codeA )     on delete cascade on update cascade,  n_codeB varchar(20) default '' not null,  constraint
B_pkeyprimary key ( e_tranB, e_codeA )
 
);

I have trigger and procedure on table B to capture any change and insert
into table logB:   create trigger trigger_b before insert or update or delete on B for each
row execute procedure log_change();

When I update e_codeA in table A, the constrain trigger will update e_codeA
in B. My trigger, trigger_b, also was trigged and procedure will record
change into table logB too.
How to write a code in my db procedure to check whether the procedure was
called by normal SQL or was called by cascade trigger.

Regards,
wit