[Coco] os9/drivewire driver problems
aawolfe at gmail.com
Sun Nov 8 06:58:32 EST 2009
First, please don't laugh, I am new and surely making many simple mistakes here.
Second, I cannot say thank you enough to everyone who has made
NitrOS9, the toolshed and drivewire possible. I'm very impressed by
how well the tools work.
I am trying to add to drivewire the ability to act as a serial port
under NitrOS9. I've managed to setup a build environment and create a
device descriptor and driver for the new device. I added the op codes
and handling routines on the server side, etc. I have write working,
but that's the easy part since the dw printer driver already did that
and I mostly just copied it.
So, I can do things like: LIST STARTUP > /T2
and everything works great.
However, read is another story. I can't seem to get anything working
properly and after several hours I am stumped.
Here's what I think I've figured out about how dw works, I might have
some things wrong.
To read a character, I think I am supposed to put my opcode in A,
pointer for the incoming data in X (usually my stack, i think?), the
number of bytes to read in Y.
Then, jsr to the DWSUB and let the magic happen? At least this is
what I think I've gleaned from the source of other modules.
According to the OS9 dev manual, the Read routine should return a
character in reg A.
So, my first attempt was:
I may be doing stupid things here, I haven't done 6809 assembler in
many years. I'm not sure what the 6, and 3, in the JSRs is for, it
seems like every write uses 6 and read uses 3 in the other modules.. ?
This "works" in the sense that the server sees the call and sends back
a byte. However, I've botched something because the process calling
read always gets a null character. If I spawn a shell on /T2, it
reads and writes bytes constantly (I think it's echoing the character
it thinks I typed) but its all null chars.
So, I thought to test I would just:
(#OP_SERREAD is the character 'C'). I was hoping then that something
like LIST /T2 would give me a stream of Cs. But instead I get Error
208, Illegal service request.
Hopefully this makes some kind of sense, I'm sure I've done something
silly but if I make Read just put a constant in A and clear B (no
errors), shouldn't I get a character every time I call Read?
Thanks for any pointers
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