Table 6-60. Truth Table For Alpha-Blending - AMD Geode LX 600@0.7W Data Book

Video Processor
Table 6-60 represents the same logic that is displayed in Figure 6-28 on page 396.
VG_CK
(Note 1) Windows
x (Note 3) x
x Not in Video
Window
Graphics Not in Alpha
Color Key Window
(VG_CK = 0)
Inside Alpha
Window x
Video Not in Alpha
Chroma Key Window
(VG_CK = 1)
Inside Alpha
Window x
Note 1. VG_CK is bit 20 in the Display Configuration register (VP Memory Offset 0008h).
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).
Note 3. x = Don't care.
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.
AMD Geode™ LX Processors Data Book

Table 6-60. Truth Table for Alpha-Blending

Configuration (Note 2)
x
x
GFX_INS_VIDEO = 0
GFX_INS_VIDEO = 1
ALPHAx_COLOR_REG_EN = 1
ALPHAx_COLOR_REG_EN = 0
x
x
GFX_INS_VIDEO = 0
GFX_INS_VIDEO = 1
ALPHAx_COLOR_REG_EN = 1
ALPHAx_COLOR_REG_EN = 0
x
x
Graphics
Data Per-pixel
Match Graphics Alpha
Cursor [31:24] = Blending
Color Key 00h Enabled
Yes x
No x
No Yes
No No
No x
No Yes
No Yes
No No
No No Yes
No x
No x
No x
No x
No x
No x Yes
No x
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.
33234H
Video Data
Match
Normal
Color Key Mixer Output
x x Cursor color
x x Graphic data
x x Video data
x x Graphic data
x x Video data
x x Color from color
register
x x Video data
No x Window alpha-
blended data
x Per-pixel alpha-
blended data
x Yes Graphic data
x No Video data
x x Graphic data
x Yes Color from color
register
x Yes Graphic data
No Per-pixel alpha-
blended data
No No Window alpha-
blended data
397