[OpenBIOS] Incorrect implementation of b?branch?

[Mark Cave-Ayland]

Stefan Reinauer wrote:

> I think you indeed hit a bug. b?branch in openbios only works in word
> definitions, not in interpretion mode. It needs similar handling as
> setup-tmp-comp/execute-tmp-comp in the definition of "if" in bootstrap.fs.

No way! I was actually looking at the code in bootstrap.fs thinking that 
the code assumed it was working inside a temporary buffer, and wondering 
if the setup-tmp-comp word would help me. Thanks for the pointer.

> In addition to that your example contains non-valid code. A b?branch
> always needs to point behind a b(>resolve) as in the below example.
> 
> here
> cc c,                   \ offset16
> \ a4 c,                 \ -1
> a5 c,                   \ 0
> 14 c, 00 c, 05 c,       \ b?branch
> 02 c, 16 c,             \ abort
> b2 c,                   \ b(>resolve)
> 9f c,                   \ .s
> 00 c,                   \ end0
> 1 byte-load

Indeed, that is my mistake. Please find the attached patch, which when 
used with your code example above now seems to do the right thing for 
b?branch:


0 > here  ok
1 > cc c,  ok
1 > a5 c,  ok
1 > 14 c, 00 c, 05 c,  ok
1 > 02 c, 16 c,  ok
1 > b2 c,  ok
1 > 9f c,  ok
1 > 00 c,  ok
1 > 1 byte-load <e> -1 1 0 -1 0 0 0 ffd79378 0 0 0 0 0 0
  ok


0 > here  ok
1 > cc c,  ok
1 > a4 c,  ok
1 > 14 c, 00 c, 05 c,  ok
1 > 02 c, 16 c,  ok
1 > b2 c,  ok
1 > 9f c,  ok
1 > 00 c,  ok
1 > 1 byte-load
byte-load: exception caught!
  ok


At least now if I find similar errors, I have an idea of how to fix them :)


Many thanks,

Mark.

-- 
Mark Cave-Ayland
Sirius Corporation - The Open Source Experts
http://www.siriusit.co.uk
T: +44 870 608 0063
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