cctech Digest, Vol 54, Issue 43

[Jeff Erwin]

>
> I came up with the following from another source.  Assumes ascii byte in
> A, returns binary in lower nibble of A


sui   3ch   ; subtract the ascii base
cpi   0ah   ; check for 0-9
rc
sui   07h   ; subtract further for A-F
ret

Jeff Erwin

pretty short and seems to work as long as valid ascii is being sent.

>
>
> > Really this is pretty easy (this does NO error checking, and only
> accepts upper
> > case characters):
>
> Okay, being a dumb ol' bit-twiddler, I couldn't resist:
>
> (input character in A)
>
> adi 0c0h
> mov b,a
> sbb a
> ani 09h
> add b
> ani 0fh
>
> Okay, folks--anyone got a shorter sans-jump one?  One that perhaps
> doesn't require an extra register?  How about one that uses a DAA to
> do something sneaky?
>
> Cheers,
> Chuck
>
>
>
>