Table 7-2, Truth table for alpha blending – AMD Geode SC2200 User Manual
Page 321
AMD Geode™ SC2200 Processor Data Book
333
Video Processor Module
32580B
Mixing/Blending Operation
Table 7-2 on page 333 shows the truth table used to create the flow diagram, Figure 7-12 on page 334, that the Mixer/
Blender logic uses to determine each pixels disposition.
Table 7-2. Truth Table for Alpha Blending
COLOR_
CHROMA_SEL
1
1.
COLOR_CHROMA_SEL: F4BAR0+Memory Offset 04h[20].
Windows
Configuration
2
2.
GFX_INS_VIDEO: F4BAR0+Memory Offset 4Ch[8].
ALPHAx_COLOR_REG_EN: F4BAR0+Memory Offsets 68h[24], 78h[24], and 88h[24].
Graphics
Data Match
Cursor
Color Key
Graphics
Data Match
Normal
Color Key
Video Data
Match
Normal
Color Key
Mixer Output
x
x
x
Yes
x
x
Cursor Color
x
Not in Video
Window
x
No
x
x
Graphics Data
Graphics Color
Key
(COLOR_
CHROMA_SEL
= 0)
Not in an Alpha
Window
GFX_INS_VIDEO = 0
No
Yes
x
Video Data
No
No
x
Graphics Data
GFX_INS_VIDEO = 1
No
x
x
Video Data
Inside Alpha
Window x
ALPHAx_COLOR_REG_EN = 1
No
Yes
x
Color from
Color Register
ALPHAx_COLOR_REG_EN = 0
No
Yes
x
Video Data
x
No
No
x
Alpha-blended
Data
Video Chroma
Key
(COLOR_
CHROMA_SEL
= 1)
Not in an Alpha
Window
GFX_INS_VIDEO = 0
No
x
Yes
Graphics Data
No
x
No
Video Data
GFX_INS_VIDEO = 1
No
x
x
Graphics Data
Inside Alpha
Window x
ALPHAx_COLOR_REG_EN = 1
No
x
Yes
Color from
Color Register
ALPHAx_COLOR_REG_EN = 0
No
x
Yes
Graphics Data
x
No
x
No
Alpha-blended
Data