mirror of
https://github.com/hsoft/collapseos.git
synced 2024-12-26 15:38:05 +11:00
2f1e635b9d
Pushed all words directly interfacing with ports and memory offsets to low level layers. This saves us the need for keeping those variables in runtime memory.
17 lines
695 B
Plaintext
17 lines
695 B
Plaintext
# Z-Offset
|
|
|
|
This LCD has a "Z-Offset" parameter, allowing to offset rows on
|
|
the screen however we wish. This is handy because it allows us
|
|
to scroll more efficiently. Instead of having to copy the LCD
|
|
ram around at each linefeed (or instead of having to maintain
|
|
an in-memory buffer), we can use this feature.
|
|
|
|
The Z-Offet goes upwards, with wrapping. For example, if we
|
|
have an 8 pixels high line at row 0 and if our offset is 8,
|
|
that line will go up 8 pixels, wrapping itself to the bottom of
|
|
the screen.
|
|
|
|
The principle is this: The active line is always the bottom
|
|
one. Therefore, when active row is 0, Z is FNTH+1, when row is
|
|
1, Z is (FNTH+1)*2, When row is 8, Z is 0. (cont.)
|