[Coco] questions about sharing memory amongst device drivers in os-9

[Aaron Wolfe]

Hi,

I've updated the server code and drivewire nitros-9 drivers to allow
up to seven "virtual" serial ports over the bitbanger.  Each virtual
port is terminated on the host in its own PTY.

In order to do this, I created additional device descriptors with
different V.PORT values but pointing to the same scwdt driver. I use
the port in calls to the driver to distinguish between them.

Everything works fine for writes, since these do not require any
coordination between devices.  I can simultaneously list out multiple
files on the coco to separate windows/session on my PC, no problem.
Drivewire really is fast!

However, for incoming data I have an issue that I could use some
guidance with.  Each device creates its own memory area.  The first
device to use the scwdt driver shares it's area with the driver, so
they can see the same memory, where the input buffers, status flags
etc are.  I can run a shell on the first port I iniz, whichever port
that might be, and everything's great.

The second third etc ports are getting their own separate device
memory area, I guess this makes sense in a real world device where
they would have separate interrupt handlers.  But in this project, I
need to use a single interrupt handler to feed multiple "devices".

Here's an example of what I mean, T1 and T2 have different static mem
areas, but both use scdwt.  Since T1 has the same addr (6000) as the
IRQ handler, it can do writes.  T2 can only do reads:

{T1|03}/DD:devs

Device Table at: 6D00

Device Desc  Driver Static  File    Usr
Name   Port  Name      Mem  Manager Cnt
-----------  -------------  ------- ---
DD   070000  rbdw3    6B00  RBF      05
Term 07FFA0  VTIO     6A00  SCF      04
T1   07FF01  scdwt    6000  SCF      03
T2   07EE02  scdwt    5E00  SCF      01

{T1|03}/DD:irqs

Polling Table at: 6EFB
 Device Table at: 6D00

 Device    Driver  IRQ   Flip
Port Mem   Name  Vector  &Mask Pty
---- ----  ------------  ----- ---
60B4 6000  scdwt   E5C6  00 01  0A


All I really need is some shared memory or other means to get bytes
into each device's buffer from the central interrupt handler, or let
the devices come get the data from a central set of buffers,
whichever.. and then the ISR needs to know the process IDs (V.BUSYs
basically) of each device so it can send the wake signal.   Actually I
have the signal handler written already but no way to get the PIDs
into it's table.

Is there a standard os-9 way to do such a thing?  Am I missing
something that would make this simpler? I've studied the os9 terch ref
and everything else I can find but nothing has become obvious to me
yet.  Any advice is much appreciated.
-Aaron