[A89] Re: _rowread
[Prev][Next][Index][Thread]
[A89] Re: _rowread
thanks for the help, the 0x0021 was a typo
on my part and thats why it didn't work.
---- On Tue, 4 Jun 2002, Joel Thompson
(joelt49@yahoo.com) wrote:
>
> OK, in order to understand _rowread, learn
something about the hardware. First, the
chart in the docs
> of _rowread of TIGCC are very useful. Now:
>
> at 0x600018 is the mask. It masks out rows
corresponding to which bits are 1. So, if
only bit 0 is 0,
> then it will only check the first row. It
returns what keys have been pressed in the
rows that
> haven't been masked out (i.e. the bit
number corresponding to the row number has
0) in 0x60001b. So,
> if you want only the key in column 0, put
a 0 in that bit number and and it with
peekIO (0x60001b),
> and it will tell you if it has been
pressed. _rowread inverts the byte at
0x60001b, so you don't have
> to do it. You got the first part
correctly, but the value you are anding it
with also allows for the
> up arrow to be pressed: 0x0021 is 00100001
in binary, so you are checking whether the
key in column 0
> or 5 is being pressed. You only want the
5th column, so and it with 0x20 instead, and
it will work
> correctly. I gave this long explanation
because understanding it helped me
understand the _rowread
> function better. If you still have
questions, refer to j89hw.txt at
http://alh.dhs.org/ti
>
89/download.php?file=http://m101.ryd.student.liu.se/J89hw.txt.
Also, you should redirect ai5 to a
> dummy handler. However, it is much easier
to use the _keytest macro instead:
>
> while (!_keytest (RR_SHIFT)) {}
>
> It handles notting bits and stuff for you.
>
>
>
> ---------------------------------
> Do You Yahoo!?
> Sign-up for Video Highlights of 2002 FIFA
World Cup
>
>
>
>
________________________________________________
Get your own "800" number
Voicemail, fax, email, and a lot more
http://www.ureach.com/reg/tag