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Video Processor Module
Mixing/Blending Operation
Table 7-3 on page 327 shows the truth table used to create the flow diagram, Figure 7-12 on page 328, that the Mixer/
Blender logic uses to determine each pixels disposition.
COLOR_
1
CHROMA_SEL
Windows
x
x
x
Not in Video
Window
Graphics Color
Not in an Alpha
Key
Window
(COLOR_
CHROMA_SEL
Inside Alpha
= 0)
Window x
Video Chroma
Not in an Alpha
Key
Window
(COLOR_
CHROMA_SEL
Inside Alpha
= 1)
Window x
1.
COLOR_CHROMA_SEL: F4BAR0+Memory Offset 04h[20].
2.
GFX_INS_VIDEO: F4BAR0+Memory Offset 4Ch[8].
ALPHAx_COLOR_REG_EN: F4BAR0+Memory Offsets 68h[24], 78h[24], and 88h[24].
AMD Geode™ SC1200/SC1201 Processor Data Book
Table 7-3. Truth Table for Alpha Blending
2
Configuration
x
x
GFX_INS_VIDEO = 0
GFX_INS_VIDEO = 1
ALPHAx_COLOR_REG_EN = 1
ALPHAx_COLOR_REG_EN = 0
x
GFX_INS_VIDEO = 0
GFX_INS_VIDEO = 1
ALPHAx_COLOR_REG_EN = 1
ALPHAx_COLOR_REG_EN = 0
x
32579B
Graphics
Graphics
Data Match
Data Match
Cursor
Normal
Color Key
Color Key
Yes
x
No
x
No
Yes
No
No
No
x
No
Yes
No
Yes
No
No
No
x
No
x
No
x
No
x
No
x
No
x
Video Data
Match
Normal
Color Key
Mixer Output
x
Cursor Color
x
Graphics Data
x
Video Data
x
Graphics Data
x
Video Data
x
Color from
Color Register
x
Video Data
x
Alpha-blended
Data
Yes
Graphics Data
No
Video Data
x
Graphics Data
Yes
Color from
Color Register
Yes
Graphics Data
No
Alpha-blended
Data
327
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