On 2020-07-03 13:19, Johnny Billquist wrote:
On 2020-07-03 13:14, Lars Brinkhoff wrote:
Johnny Billquist wrote:
I am not at all sure I agree with that... I think you too should look
at the VT100 technical manual and see how soft scrolling is done, as
an example of a place where the hardware emulation can actually become
rather tricky...
Now I'm curious. If you have a title and a page number, I will take a
look.
I posted this last night, but here it comes again:
You really should check out of smooth scrolling on the VT100 is
accomplished...
(http://www.bitsavers.org/pdf/dec/terminal/vt100/EK-VT100-TM-003_VT100_Technical_Manual_Jul82.pdf,
page 4-97, section 4.7.9 - "Split Screen Smooth Scrolling". Emulating
those hardware tricks are not going to be easy...
Oh, and just for the people who don't want to read a lot of
documentation, the smooth scrolling is essentially done by the terminal
by changing where the source of the video signal generation picks up
font information, so that you actually start scanning at a specific line
of the font definition for characters at the video generation stage. And
then you do additional trickery so that you start scanning the next line
data as well, so that compared to the line above, this line is generated
using data from two lines, and your picking up font definition lines
with offsets, and then you need a bit of special casing for the first
and last lines of the region.
I hope that made sense... :-)
Johnny
--
Johnny Billquist || "I'm on a bus
|| on a psychedelic trip
email: b...@softjar.se || Reading murder books
pdp is alive! || tryin' to stay hip" - B. Idol
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