10 Dec
2005
10 Dec
'05
2 p.m.
I thought I saw all the postings in this thread, but I missed where
you posted that, Chuck. Sorry.
The advantage of the method, and yours below, is that they're
deterministic. Another is that it's position independent. Now,
admittedly, in 25+ years of writing software, I've only had one occasion
where I needed it to be deterministic, and it was on a 8051 (same method
works on any processor with DAA). I've never had to worry about it
having to be PIC.
I like using the DAA method for testing job candidates. It's not a
pass/fail sort of thing, but if they can get reasonably close to
figuring out what it's doing, they've earned points. I usually throw in
some other little questions like "What is Duffs Device" and a few
others, just to see how in-depth they are (I've never seen Duffs used in
real-world code, but it's useful trick to be aware of, and indicates a
good understanding of the way C can be twisted).
--jc
Chuck Guzis wrote:
On 12/10/2005 at 12:03 AM woodelf wrote:
It gets me confused before it returns. I think
I've seen the same code
in the 386 book I have.
If it is the program segment I am thinking of that is a cute trick if
it returns AL as a ascii character.
Didn't I just post that selfsame code yesterday, albeit in 8080?
How about:
and al,0fh
xlate hextable
hextable db '0123456789ABCDEF'
Straightforward and fewer instructions. Not only that, you can use ANY
character code (say, EBCDIC) for output.
Or even:
and al,0fh
movzx ebx,al
mov al,hextable[ebx]
--Chuck