[TUHS] Introduction
Jose R. Valverde
jrvalverde at cnb.csic.es
Wed Jun 25 19:40:40 AEST 2008
Oliver:
Right, it seems that I mistransliterated the code in a hurry or confusion.
I notice that on prf.c *adx is a pointer to be assigned to s, whereas in
sys2.c uap->linkname is the pointer itself thas is assigned to u.u_dirp.l
So my initial transliteration was wrong as I was assigning *uap->linkname
instead of uap->linkname.
Reviewing the assembler you submitted I notice it looks almost like what you
wanted but for @rr2 instead of rr2 so it might have been the extra * I
wrongly added in front of the parenthesized & expression and the erroneously
placed parenthesis (which I also got wrong) the reason for not getting what
you wanted.
If on prf.c you have in printf
register unsigned int *adx;
char *s;
adx = &x1;
...
s = (char *) * adx;
and was recoded on WEGA in printfv
register unsigned *adx;
register char *s;
adx = x1;
...
s = (char *)(*(long *)adx & 0x7F00FFFF);
then maybe the right code on sys.c would be a change from
caddr_t u.u_dirp; /* char *, from param.h user.h */
register struct a {
char *target;
char *linkname;
} *uap;
...
u.u_dirp.l = (caddr_t) uap->linkname;
to
caddr_t u.u_dirp.l; /* char *, from param.h user.h */
register struct a {
char *target;
char *linkname;
} *uap;
...
u.u_dirp.l = (caddr_t) ) ((long *) uap->linkname & 0x7F00FFFF);
Note also the difference in parenthesis usage with what you said you had
tried on http://pofo.de/P8000/problems.php
u.u_dirp.l = (caddr_t)(((long)uap->linkname) & 0x7F00FFFF);
I fear that I was too tired when I wrote my previous posting and made two
many mistakes.
Anyway, the first step should be to check what prf.c generates as assembler
at these & lines when compiled. If it matches the sample code you mention you
have in other places then it means the same device was used to generate it
(which I would guess is the case) and then it should be a matter of thinking
clearly of what is being assigned. I do believe the surviving trace in prf.c
is the key to understanding the problem assembly code.
j
On Mon, 23 Jun 2008 18:11:01 +0200 Oliver Lehmann <lehmann at ans-netz.de>
wrote:
> Hi Jose,
>
> Jose R. Valverde wrote:
>
> >
> > u.u_dirp.l = (caddr_t) (*((long *)(uap->linkname &0x7F00FFFF)))
> >
>
> leads to:
>
> "sys2.c":305: operands of "&" have incompatible types
> Error in file sys2.c: Error. No assembly.
>
>
> I've changed it to:
> u.u_dirp.l = (caddr_t) (*((long *)((long)uap->linkname &0x7F00FFFF)));
>
> and this produces:
>
> ldl rr2,rr8(#4)
> and r2,#32512
> ldl rr4, at rr2
> ldl _u+78,rr4
>
> not exactly the wanted code :(
>
> Greetings, Oliver
>
> --
> Oliver Lehmann
> http://www.pofo.de/
> http://wishlist.ans-netz.de/
--
These opinions are mine and only mine. Hey man, I saw them first!
José R. Valverde
De nada sirve la Inteligencia Artificial cuando falta la Natural
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