The cc65 tool chain comes with V.24 drivers so it seems reasonable to use the existing Contiki SLIP driver to implement network access via SLIP as alternative to Ethernet.
Some notes:
- The Ethernet configuration was simplified in order to allow share it with SLIP.
- The Contiki SLIP driver presumes an interrupt driven serial receiver to write into the SLIP buffer. However the cc65 V.24 drivers aren't up to that. Therefore the main loops were extended to pull received data from the V.24 buffers and push it into the SLIP buffer.
- As far as I understand the serial sender is supposed to block until the data is sent. Therefore a loop calls the non-blocking V.24 driver until the data is sent.
On all platforms there's only one V.24 driver available. Therefore V.24 drivers are always loaded statically.
On the Apple][ the mouse driver is now loaded statically - independently from SLIP vs. Ethernet. After all there's only one mouse driver available. However there's a major benefit with SLIP: Here all drivers are loaded statically. Therefore the dynamic module loader isn't necessary at all. And without the loader the heap manager isn't necessary at all. This allows for a reduction in code size roughly compensating for the size of the SLIP buffer.
- The default mouse driver is now always named 'contiki.mou'.
- Alternative mouse drivers are present in the disk images.
- Users can select their mouse driver by renaming the files.
Both the source code and the cc65 compiler have changed. So it made sense to review which object files are to be compiled for placement in the Language Card.
Relevant cc65 changes...
General:
- The compiler generates "extended" dependency info (like gcc) so there's no need for postprocessing whatsoever :-)
- The linker is very pernickety regarding the ordering of cmdline options so a custom linker rule is necessary :-(
Apple2:
- The various memory usage scenarios aren't specified anymore via separate linker configs but via defines overriding default values in the builtin linker config.
Atari:
- The builtin linker config allows to override the start addr so there no more need for a custom linker config.
- The C library comes with POSIX directory access. So there's no more need for for a custom coding.
CBM:
- The C library comes with POSIX directory access. So there's no more need for for a custom coding.
Contiki now leverages that feature to place process.o, etimer.o and uip_arp.o in HIGHCODE. These files were carefully chosen as:
- they are necessary for all Ethernet apps
- their size doesn't depend on configuration macros
- they fill the available space nicely (with a little reserve for changes in the source or the compiler)
ProDOS requires for each opened file a user-supplied page-aligned 1024 byte i/o buffer. This makes the generic POSIX file i/o library contained in the cc65 C-library quite heavyweight.
In contrast the lightweight pfs implementation uses the uIP packet buffer as ProDOS i/o buffer. Therefore:
- Only one file may be open at any time.
- That file may not be open while the uIP packet buffer is used by uIP. The open()/read()/close() sequence should be completed before Contiki event scheduling or inside handling a single Contiki event.
- The uIP packet buffer must be large enough to hold the ProDOS I/O buffer. Depending on the position of the uIP buffer in memory this means between 1024 and 1024 + 256 bytes. Therefore in an Ethernet environment setting the MTU_SIZE to at least 1266 is safe (So the default of 1500 is just fine).
