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SubjectRe: [PATCH RFC v3] auxdisplay: charlcd: Fix and clean up handling of x/y commands
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On 27 Feb 2018 23:09, Miguel Ojeda wrote:> @@ -469,24 +543,11 @@ static
inline int handle_lcd_special_code(struct charlcd *lcd)
> }
> case 'x': /* gotoxy : LxXXX[yYYY]; */
> case 'y': /* gotoxy : LyYYY[xXXX]; */
> - if (!strchr(esc, ';'))
> - break;

Might want to keep this. It's in line with all other cases and prevents
calling parse_xy with input that has no chance of being correct due to
missing final ';'.

> + /* If the command is valid, move to the new address */
> + if (parse_xy(esc, &priv->addr.x, &priv->addr.y))
> + charlcd_gotoxy(lcd);

While not in the original code, the inputs are now not clamped to width
and height.
That means for a two-line display ^[[Ly02; will actually end up on line
y = 1, not y = 2 % 2 = 0, because the four-line display logic bumps the
address up.
The same goes for going over lcd->width/lcd->bwidth in the x coordinate.
For four-line displays that ends up going to the line y + 2, because the
buffer is split in the middle.
The distinction between lcd->width and lcd->bwidth depends on whether it
makes sense to put the cursor outside the visible area or not.

Regards,

Robert

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