Passing the table name as a function argument in PLPGSQL

Hello,

Is it possible to pass the name of the table to update to a given function ?

For example, how can I do something like:

CREATE FUNCTION compute_ipaddr(CHARACTER VARYING, INET)
AS $_$
DECLARE
tbl_name ALIAS FOR $1;
module_ipaddr ALIAS FOR $2;
BEGIN
UPDATE tbl_name SET ipaddr = module_ipaddr ....

END;
$_$
LANGUAGE PLPGSQL;

Since this does not work, I have to do

IF tbl_name = 'controller' THEN
UPDATE controller SET ipaddr = module_ipaddr ...
ELSE IF tbl_name = 'server' THEN
UPDATE server SET ipaddr = module_ipaddr ...
[ ...]

Is there a technique to pass the table name and so make the code more
generic ?

Thanks for your help

Vincent