[PATCH] CGA/VGA improvements
Erik van der Kouwe
To be able to run Windows I'll need more graphics capabilities. This
patch is the first step. Changes made:
- Text resolution is dynamic and can be changed by the guest (frontend
is optionally notified)
- Video memory address can be selected by the guest (0xA0000, 0xB0000 or
0xB8000)
- All CGA/VGA IO ports can now be properly read from and written to
(although most are still ignored)
- Graphics modes are not supported yet, but at least they are reported
to the user on the text screen
- Graphics wrap around the video memory boundary properly
- It seems I fixed some bug as I no longer need the cursor-position
workaround to detect missed updates in the curses console (this makes it
more efficient because there are no more spurious updates)
I've tried to retain passthrough capabilities everywhere, but
unfortunately I couldn't test this on MINIX.
Since devices/cga.c has changed a lot, I've included the entire file to
potentially make merging easier (although it is also in the patch, which
is based on revision 9c9370627c5a95e3abaa1b4a6b78f6f5846f53cc, the
latest I can obtain here).
With kind regards,
Erik