[OpenBIOS] PIC Passthough( VGA )

[Segher Boessenkool]

On Tue, Dec 19, 2017 at 11:20:57AM -0500, Jd Lyons wrote:
> > On Dec 19, 2017, at 10:56 AM, Segher Boessenkool <segher at kernel.crashing.org> wrote:
> > On Tue, Dec 19, 2017 at 10:40:08AM -0500, Jd Lyons wrote:
> >> Looks like the spot were I’m stuck is:
> >> 
> >> b(;) ( 0x0c2 ) 
> >> 25612: b(') ( 0x011 ) (unnamed-fcode) [0xc84] 
> >> 25613: b(to) ( 0x0c3 ) (unnamed-fcode) [0x9a9] 
> >> 25614: (unnamed-fcode) [0xe34] 
> >> 25615: (unnamed-fcode) [0xdff] 
> >> 25616: (unnamed-fcode) [0x93d] 
> >> 25617: b(lit) ( 0x010 ) 0xf
> >> 25618: <> ( 0x03d ) 
> >> 25619: b?branch ( 0x014 ) 0x0026 ( =dec 38)
> >> 25620:     (unnamed-fcode) [0x9bd] 
> >> 25621:     b(lit) ( 0x010 ) 0xff
> >> 25622:     and ( 0x023 ) 
> >> 25623:     my-space ( 0x103 ) 
> >> 25624:     + ( 0x01e ) 
> >> 25625:     (unnamed-fcode) [0xa08] 
> >> 25626:     b(lit) ( 0x010 ) 0x6
> >> 25627:     and ( 0x023 ) 
> >> 25628:     b(lit) ( 0x010 ) 0x4
> >> 25629:     = ( 0x03c ) 
> >> 25630:     b?branch ( 0x014 ) 0x0009 ()
> >> 25631:         b(') ( 0x011 ) (unnamed-fcode) [0x9c1] 
> >> 25632:         b(to) ( 0x0c3 ) (unnamed-fcode) [0x9c0] 
> >> 25633:     b(>resolve) ( 0x0b2 ) 
> >> 25634: b(>resolve) ( 0x0b2 ) 
> >> 
> >> It seems to break right here……………………………….
> > 
> > Those b?branch are in interpret mode, I don't know if that is handled
> > correctly (it is tricky to get right).
> > 
> 
> So, is it hanging at b(>resolve) ( 0x0b2 ) or (unnamed-fcode) [0xddf] ?
> 
> Do we need to work on how Openbios handles  b?branch?

That is my suspicion yes.

>From fcode.fs:
===
\ b?branch ( continue? -- )
\   Conditional branch FCode. Followed by FCode-offset.

: b?branch
  fcode-offset 0< if \ if we jump backwards, we can forsee where it goes
    ['] do?branch ,
    resolve-dest
    execute-tmp-comp
  else
    setup-tmp-comp ['] do?branch ,
    here 0
    0 ,
  then-
  ; immediate
===

This is not compliant; it should behave differently in interpretation
state (just skip stuff).  This matters if e.g. the stuff inside the "if"
does not compile properly, etc. (it can be used to implement "[if]").

> Is there anyway to make detok be less verbose, and just print the raw Forth?

It's a simple matter of coding ;-)

The thing is, those words do not have names in the compiled FCode.  The
things I detokenised by hand I gave names like "xddf" which is friendlier;
but your program might actually have names like that, too...


Segher