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Updated screen Docu

This commit is contained in:
lucic71 2020-06-23 11:05:15 +03:00
parent 52415636f3
commit 8a1fb40613
1 changed files with 16 additions and 2 deletions
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18
modules/screen/Documentation.txt
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@ -30,6 +30,21 @@ Depending of the mode setup, attribute bit 7 may be used for blinking thus
only 3 bits remain for background color. Attribute bit 3 may be used for
foreground intensity. Attribute bit 0 may be used for underline.
Cursor
------
Moving the cursor on the framebuffer is done via two different I/O ports. The
cursor position is a 16 bit integer that must be sent to a 8 bit I/O port.
We do that in two turns.
First, we send a byte to the command port that tells it to receive the highest
8 bits of the position, then we send the byte to data port.
Second, we send another byte to the command port that tells it to receive the
lowest 8 bits of the position. then we send the byte to data port.
The above mentioned ports are defined as macros in include/cursor.h. The
command bytes are defined in the same header.
II. Implementations
------------------
@ -39,8 +54,7 @@ There are two main operation to perform: sinit and swrite.
sinit will initiate the screen by filing the framebuffer with whitespaces
(ASCII character 0x20).
swrite will put characters on the screen without updating the cursor (will
be fixed in future commits).
swrite will put characters on the screen and will update the cursor too.
III. Further work
-----------------