Parametric G42 G41 lead in

The G41 and G42 lead ins have many conditions to respect, does anyone have a subroutine to call to make a lead in with the least movement possible according to tool diameter and direction of next movement?

this is given by the CAM module
like in FreeCAD with Roll on roll off LEAD in on any point of the contour
or as well in heekscad
the tool diameter needs to be specified by a user as well as the direction
outside inside left right climb conventionell

so there are many options

and ofcause you can do it easy by hand

i got videos online to show an all the above cam systems on how2