> %{
> %}
>
> %%
> stop print("Stop!! recieved
n");
> start print("Start -> recieved
n");
> %%

the fix for this should be to add
#include
#include

between %{ and %} but this doesn't work because
lex includes stdio.h before it processes %{ %}.
you'll need to write a shim, fixlex.c, that goes like this

#include
#include
#include "lex.yy.c"

that is unless you want to dive into the lex source. :-)

- erik