Re: [Simulavr-devel] Adding UART support

[ken restivo]

-----BEGIN PGP SIGNED MESSAGE-----
Hash: SHA1

On Mon, Sep 09, 2002 at 09:39:42PM -0700, Theodore A. Roth wrote:
> [OT: Ken, can you try to make your email client wrap lines? This looks 
> aweful in the archives. Thanks.]

Just can't please 'em all. Hmm, can't make the archive bot do the wrapping? ;-)
I used to wrap, but got too many complaints from people about long URL's 
getting mangled. I guess I can manually wrap 'em for this list.

> 
> Sorry if I don't give much feed back on this right now. The wine makes it a 
> bit difficult to grasp what your saying. ;-)

DON'T DRINK AND CODE! :-) Drinking and emailing can be even more hazardous.

> 
> Go ahead and start hacking on this. I'd avoid tying into stdin/stdout if 
> possible. I know that I already do that with the port io but, I want it to 
> go away.

Will do. 

> 
> Also, I'm going to be doing some major refactoring of the way virtual 
> devices are mapped into the memory space. I hope this is won't be visible at 
> the level you want to work, but I don't know at this point, as it's only 
> been an idea brewing in my head and I haven't looked into details yet. 
> Hopefully I can make things easier and faster.

Sure. As long as the VDevice object interface doesn't change, it shouldn't
screw me up too bad.

- -ken
- -----------
> 
> 
> On Mon, 9 Sep 2002, ken restivo wrote:
> 
> :)Ted-
> :)
> :)I need to add UART support in order to simulate an app that is
> :)UART-centered.
> :)
> :)I was going to do my usual "quick 'n ugly" hack method, but then I thought
> :)it might be nice to try to do it "the right way", so that maybe it can get
> :)merged in and maybe I'll have a few less "M"'s and "C"'s showing up when I
> :)do a cvs update ;-)
> :)
> :)So, I notice there's no HOWTO for adding virtual device support, just an
> :)interesting README on external devices and some "FIXME: empty place
> :)holder" in the docs, but... perhaps this can be the start of one? I'll be
> :)glad to write up whatever I discover along the way, so that others may
> :)have an easier time of it.
> :)
> :)So far, I'm thinking of attaching the UART to either stdin/out by default,
> :)or a pty or fifo specified on the command line. I'm going to start with
> :)something simple: no interrupts, just a handler for when UDR is written,
> :)which writes the char out to the fd, and a handler for when UDR is read,
> :)which simply reads from the fd. As for reading chars, I need to be able to
> :)accept both literal bytes and hex representations of bytes in ASCII. I was
> :)going to do this by checking the input fd for the chars "0x", and dispatch
> :)anything up to a newline to the hex2nib() from gdbserver.c (er, and maybe
> :)moving hex2nib() to utils.c?). Probably need a switch on the command line
> :)to turn that escape sequence off, in cases where the simulated UART is
> :)talking to something that sends bytes literally. There are probably other
> :)(better?) ways to do this though.
> :)
> :)Of course, all this would assume that RXC is always set, which is hideous,
> :)but will work for the kind of tightly-polled I/O that my target app does.
> :)Adding RXC and interrupt support to the UART looks like it would get
> :)really hairy: the simulator would have to select/poll the fd, then set the
> :)RXC flag and trigger the IRQ_UART_RX interrupt, etc.  I'm not sure where
> :)such a function should reside. TXC might be OK to leave always set, or
> :)maybe later on pol the fd for writablity before setting it (maybe even
> :)hairier if it's a fifo).
> :)
> :)My apologies if the very discussion of all this slash-and-burn hacking
> :)makes you nauseous ;-). Please let me know what the "rules of good
> :)conduct" are for a new VDev, and I'll be glad to follow them.
> :)
> :)So here's what I think the steps might be:
> :)    - Create the new files (uart.[ch])
> :)    - Add them to the Makefile.am
> :)    - Put the object stuff in the .h file
> :)            - Define an enum for the base, size, and indexes for any regs 
> needed
> :)            - Create enums for the bits and masks for any regs needed
> :)            - Create the struct for the VDevice object
> :)                    - Include byte's for the registers indexed above
> :)                    - Read the simluavr object model docs several more 
> times ;-)
> :)            - Define new/consruct/destroy methods
> :)    - Write the object methods in the .c file
> :)    - Add the vdev to the devsupp.c file (?)
> :)    - Add the globals and command line-switches, if any, into main.c
> :)    - Write a short test program for test_c (or test_asm)
> :)            - Uh, make sure it works.
> :)    - Run the regression tests
> :)            - Install python ;-)
> :)    - Submit a nice clean patch to the list, if desired
> :)            - Follow the hacking guidelines in the docs
> :)                    - Er, *write* the hacking guidelines for the docs ;-)
> :)    - Anything else?
> :)
> :)
> :)Thanks for your patience.

- -- 
- ---------------
The world's most affordable web hosting.
http://www.nearlyfreespeech.net
-----BEGIN PGP SIGNATURE-----
Version: GnuPG v1.0.6 (GNU/Linux)
Comment: For info see http://www.gnupg.org

iD8DBQE9folre8HF+6xeOIcRAs08AKDbu8FvBuG6ggykeKFNnzUElbLFdwCgjQzg
uYbmvRvu3uGUchl9aijyiag=
=QQNa
-----END PGP SIGNATURE-----