Re: Making a BSD system more braille friendly

[Michael <macallan%netbsd.org@localhost>]

Hello,

On Sat, 31 Dec 2016 15:03:08 +0100 (CET)
Enrico Mioso <mrkiko.rs%gmail.com@localhost> wrote:

> Hello to all of you reading this message.
> 
> Sorry for my possibly ugly message: english isn't my native language.
> My name is Enrico: and I am a blind computer user. I currently am
> using Linux, with the help of a software called BRLTTY (of which
> NetBSD has a port): so I can read what's on the screen via a device
> called Braille Display. There are different vendors of such devices,
> and each one uses it's protocol in general. Different models may need
> different protocols, too.

> The problem, as you'll know, is that in a *BSD kernel, there is no
> such interface allowing an user-space process to inspect the content
> of the console. On Linux systems, this is feabible via the /dev/vcs*
> interface (VCS(4)), which is infact used by BRLTTY. On BSD, the used
> approach was to patch an user-space application, namely GNU screen,
> to be able to access it's memory.

Actually, wsdisplay can do that, more or less, under the right
conditions. Many wsdisplay drivers use text buffers, and support
ioctl(WSDISPLAYIO_GETWSCHAR) to read those buffers, one character at a
time. Of course that's far from perfect for what you need but it's
probably enough.
For something less kludgy, it would not be all that hard to put those
text ( and attribute ) buffers into their own pages and allow userland
to mmap() them. Supporting vcs(4) doesn't sound overly difficult
either - would be a bit hackish though, since vcs apparently expects
VGA-ish attributes and characters, while most wsdisplay drivers use
something entirely different.

have fun
Michael