Dear Philipp and Maarten, I was just checking and got this far: the assembler contains a special case for mcs51 (I think ds390 is essentially the same thing). After making a simple general change in the assembler, the rel files look ok, but the rst file still is broken. So there probably is a similar special case in the linker. But I have not checked that code yet.
The relevant code in the assembler is in asout.c, look for R_MSB and R_HIB handling with thrdbyte(). Eric > -----Oorspronkelijk bericht----- > Van: Philipp Klaus Krause [mailto:p...@spth.de] > Verzonden: donderdag 29 maart 2018 13:44 > Aan: sdcc-user@lists.sourceforge.net > Onderwerp: Re: [Sdcc-user] How to deal bytewise with 24-bit symbols in > asxxxx? > > > Am 29.03.2018 um 13:08 schrieb Maarten Brock: > >> Am 24.03.2018 um 20:21 schrieb Philipp Klaus Krause: > >>> Am 24.03.2018 um 20:00 schrieb Maarten Brock: > >>>> How about what the mcs51 back end does: just shift right by 8: > >>>> ; genAssign > >>>> mov dptr,#___fail_PARM_2 > >>>> mov a,#___str_3 > >>>> movx @dptr,a > >>>> mov a,#(___str_3 >> 8) > >>>> inc dptr > >>>> movx @dptr,a > >>>> > >>>> Maarten > >>> > >>> I some places the stm8 backend deos the same. But AFAIK > #___str_3 is the > >>> full symbol, and onlybecasue of the assignment to a do > the upper bits > >>> get thrown away. This might create issues for peephole rules that > >>> combine two 8-bit loads into a 16-bit load. > >>> > >>> Philipp > >> > >> Unfortunately, it seems 24-bit symbols are simply not > really supported > >> in the assembler. > >> > >> #(s >> 8) gets the middle byte, just like #>s. #(s >> 16) > gets the lower > >> byte, jsut like #<s. Using #(s >> 8) where a 16-bit value is needed > >> results in the following instruction being overwritten in > the linker. > >> > >> That means that the stm8 large memory model will have to do without > >> function pointers. > >> > >> Full support for function pointers would need: > >> 1) A way to get individual bytes of 24-bit symbols > >> 2) A way to get the upper 16 bits of 24-bit symbols > >> > >> Philipp > > > > If that is true, then the ds390 target is totally broken > and the huge > > model for mcs51 is broken as well. I'm sure this used to work. > > > > ISTR that the assembler has support for every odd kind of > number of bits > > per address word, including 24 bit. Is the address size maybe set up > > incorrectly? > > > > Maarten > > I had also tested with ds390, and it seemed to work there. Maybe there > is some functionality in the ds390 assembler that would have to be > ported to the stm8 one. > > Philipp > > > -------------------------------------------------------------- > ---------------- > 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 > ------------------------------------------------------------------------------ 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
