>> Am 19.02.2018 um 10:50 schrieb Maarten Brock: >> > >> > Do I understand correctly that your STM8 has code memory >> above 0xFFFF? >> > So the problem is that SDCC only generates 16 bit jump/call >> > instructions and thus cannot reach 0x10000 and above, but >> it can 'overflow' into that area. >> > >> > Does the STM8 have separate 24 bit jump/call instructions? >> >> Yes. They are mostly ok, but function calls get awkward. >> Where it gets really awkward is data above 64K. >> >> > Or is it a special mode like on the DS390? Or is one supposed >> > to use bank switching? >> > And are there also STM8 versions with only memory below 64k? >> >> Only very few STM8 have memory above 64K. > > All STM8 parts with more than 32 kB flash currently cannot be used to > their full potential with SDCC. > > Looking at the ST website, at the moment this means 58 of the 138 > variants. Including the interesting ones of course. ;-)
That is not a very few. As I understand it now flash and thus code memory always starts at 0x8000. > A while ago I did some experiments (sadly not completed yet) by adding a > 24 bit mode to the SDCC STM8 port. Instead of CALL/RET, CALLF/RETF are > emitted and the stack calculations need to cope with 3 instead of 2 > bytes for the return. For the constants section I cheated a bit and made > an option to place this segment before the code segment, so for most (of > my) programs no further changes would be needed. > > Eric That sounds like a sane approach (and not cheating). It is more or less how I would implement the large memory model as described by Philipp. Maarten ------------------------------------------------------------------------------ Check out the vibrant tech community on one of the world's most engaging tech sites, Slashdot.org! http://sdm.link/slashdot _______________________________________________ Sdcc-user mailing list Sdcc-user@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/sdcc-user
