Table 7-10. cursor memory organization -25 – Cirrus Logic EP93xx User Manual
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Copyright 2007 Cirrus Logic
Raster Engine With Analog/LCD Integrated Timing and Interface
EP93xx User’s Guide
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“Start” is the beginning word location of the part of the cursor image to be displayed first. The
image is 2-bits per pixel, and is stored linearly. The amount of storage space is dependent on
the width and height of the cursor. The two bits per pixel stored define screen image
(transparent), invert screen image, display color1, and display color2.
The 2-bits per pixel stored cursor image is displayed as:
00 - Transparent
01 - Invert video stream
10 - CursorColor1 during no blink or CursorBlinkColor1 during blink
11 - CursorColor2 during no blink or CursorBlinkColor2 during blink
“Reset” is the beginning word location of the part of the cursor which is displayed next after
reaching the last line of the cursor. These locations are necessary for dual scan display of
cursor information. If the cursor is totally in the upper half or lower half of the screen, the Start
and Reset locations are the same. Otherwise, the cursor will start being overlaid on the video
information at the start address, and when the dual scan height counter generates a carry,
the cursor overlay will jump to the reset value. The cursor will then continue to be overlaid
when the Y location is reached, and will jump to the start address value when the height
counter for the upper half generates a carry.
Offsetting these values and changing the width of the cursor to be different from the cursor
step value allows the right 48, 32, or 16 pixels of a larger cursor to be displayed only.
Furthermore, offsetting the starting X location off of the left edge of the screen will allow pixel
placement of the cursor off of the screen edge.
The size is specified as: width adjustable to 16, 32, 48, or 64 pixels, a height in lines up to 64
pixels (controls the top half of the screen only in dual scan mode), a step size for the number
of words in a cursor line (up to 4), and a height of up to 64 lines on the bottom half of the
screen (used in dual scan mode only).
The Y location value controls the starting vertical Y location of the cursor image. The value is
compared to the vertical line counter and should be set by software to be between the active
start and active stop vertical line values. The cursor hardware will clip the cursor at the
bottom of the screen. To prevent cursor distortion, the new Y location value will not be used
until the next frame.
Table 7-10. Cursor Memory Organization
32-bit Word
Byte
3
2
1
0
Bit
30
28
26
24
22
20
18
16
14
12
10
8
6
4
2
0
Pixel
15
14
13
12
11
10
9
8
7
6
5
4
3
2
1
0