2 gamma ram, 3 video processor module display interface, 4 video interface – AMD Geode LX [email protected] User Manual
Page 397: Table 6-60, Truth table for alpha-blending
AMD Geode™ LX Processors Data Book
397
Video Processor
33234H
Table 6-60 represents the same logic that is displayed in Figure 6-28 on page 396.
6.7.5.2
Gamma RAM
Either the graphics or video stream can be routed through
an integrated palette RAM for gamma-correction of the
data stream or (for video data) contrast/brightness adjust-
ments.
A bypass path is provided for either the graphics or video
stream (depending on which is sent through the gamma
RAM).
6.7.5.3
Video Processor Module Display
Interface
The Video Processor module connects directly to either the
internal CRT DACs, or provides a standard digital TFT
interface.
6.7.5.4
Video Interface
The VP uses a two-wire protocol to control the sequence of
data on the video port. This protocol consists of VID_VAL
and VID_RDY. VID_VAL indicates the DC has placed valid
data on the 32-bit VID_DATA bus. VID_RDY indicates the
VP is ready to accept video data for the next video source
line. The VP typically starts fetching video data five scan
lines before the data is required for display.
Table 6-60. Truth Table for Alpha-Blending
VG_CK
(Note 1)
Note 1.
VG_CK is bit 20 in the Display Configuration register (VP Memory Offset 0008h).
Windows
Configuration (Note 2)
Note 2.
GFX_INS_VIDEO is bit 8 in the Video De-interlacing and Alpha Control register (VP Memory Offset 0098h).
ALPHAx_COLOR_REG_EN are bit 24 in the Alpha Window Color registers (VP Memory Offsets 0D0h, 0F0h, and 110h).
Graphics
Data
Match
Cursor
Color Key
Graphics
[31:24] =
00h
Per-pixel
Alpha
Blending
Enabled
Video Data
Match
Normal
Color Key
Mixer Output
x (Note 3)
Note 3.
x = Don’t care.
x
x
Yes
x
x
x
Cursor color
x
Not in Video
Window
x
No
x
x
x
Graphic data
Graphics
Color Key
(VG_CK = 0)
Not in Alpha
Window
GFX_INS_VIDEO = 0
No
Yes
x
x
Video data
No
No
x
x
Graphic data
GFX_INS_VIDEO = 1
No
x
x
x
Video data
Inside Alpha
Window x
ALPHAx_COLOR_REG_EN = 1
No
Yes
x
x
Color from color
register
ALPHAx_COLOR_REG_EN = 0
No
Yes
x
x
Video data
x
No
No
No
x
Window alpha-
blended data
x
No
No
Yes
x
Per-pixel alpha-
blended data
Video
Chroma Key
(VG_CK = 1)
Not in Alpha
Window
GFX_INS_VIDEO = 0
No
x
x
Yes
Graphic data
No
x
x
No
Video data
GFX_INS_VIDEO = 1
No
x
x
x
Graphic data
Inside Alpha
Window x
ALPHAx_COLOR_REG_EN = 1
No
x
x
Yes
Color from color
register
ALPHAx_COLOR_REG_EN = 0
No
x
x
Yes
Graphic data
x
No
x
Yes
No
Per-pixel alpha-
blended data
x
No
x
No
No
Window alpha-
blended data