Re: scroll modes

["Antonino A. Daplas" <adaplas@gmail.com>]

Knut Petersen wrote:
> Antonino A. Daplas schrieb:
> 
>> Knut Petersen wrote:
>>  
>>
>>> Geert Uytterhoeven wrote:
>>>
>>>   
>>>> Ywrap has been working fine with amifb since ages (unless someone
>>>> broke it very
>>>> recently).     
>>> We are talking about scrollmode = SCROLL_WRAP_MOVE ?
>>>   
>>
>> Try this patch.
>>
>>  
>>
> It doesn´t help. I cecked the values for rows and vrows and believe that
> they are ok.
> To be sure that we are not talking about different things: How _should_
> this mode
> work? If I use ywrap, why is it called scroll_wrap_MOVE? It should not
> be necessary
> to move anything around  when using ywrap ...

You still have to, because the console can ask for a partial scroll.
For example, assume you have a screen of 20 lines, the console can, for
example, ask to scroll rows 5-10 up by 1 line to row 4-9, leave rows 0-3 and
11-19 in the same place. So fbcon will adjust the yoffset, but has to move
rows 0-3 and 11-19 so they appear stationary to the user.

However, if the request for scrolling is a screenful at at time (ie,
move entire screen contents up by 1 line), then I don't think any
bmoves will be called.  Here's a snippet from the fbcon_scroll
(comments are mine):

	if (t > 0) /* if top is at origin, do not move */
		fbcon_bmove(vc, 0, 0, count, 0, t,
			    vc->vc_cols);
	ywrap_up(vc, count); /* adjust yoffset */

	if (vc->vc_rows - b > 0) /* if bottom is at end, do not move */
		fbcon_bmove(vc, b - count, 0, b, 0,
			    vc->vc_rows - b,
			    vc->vc_cols);

Tony

P.S: Ywrapping is very old code, and I think Geert can explain the code
much better than I.


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