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Table 7-3, Truth table for alpha blending – AMD Geode SC1201 User Manual

Page 327

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AMD Geode™ SC1200/SC1201 Processor Data Book

327

Video Processor Module

32579B

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.

Table 7-3. 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

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