RE: [lwip-users] TCP checksumming

[Bill Auerbach]

> > One problem however: If I define LWIP_CHKSUM in my sys_arch.h,
> > inet_chksum.c doesn't know about it. I had to add #include
> > "sys_arch.h" to inet_chksum.c. In order to override LWIP_CHKSUM
> > without changing source code, shouldn't include sys_arch.h?
> >
> I don't think so: sys_arch.h is supposed to provide things needed for
> the sys layer (like threads, mboxes and semaphores). When compiling with
> NO_SYS=1, the whole stack should still be compilable without the whole
> sys_arch.h file. You will have to put the definition somewhere else.

Is the comment in inet_chksum.c wrong then?

 * If you create
 * your own version, link it in and in your sys_arch.h put:
 * 
 * #define LWIP_CHKSUM <your_checksum_routine>

Sounds like LWIP_CHKSUM doesn't belong in sys_arch.h.  If it does (and maybe
should because it's probably CPU-dependent), how will inet_chksum know about
it without having an #include "sys_arch.h" in inet_chksum.c?

I don't think this is a NO_SYS issue.  If you say it is, why?  Checksumming
is a basic function whether we use an OS or not.

Bill