Intel® 815 Chipset: Graphics Controller PRM, Rev 1.0

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15.4.12. Overlay Alpha Blend Window Position/Size Registers

These registers allow for the alpha blending of a subsection of the overlay window positioning of the overlay data relative to the graphics display or the secondary display active region. It allows pixel accurate positioning. The Overlay Alpha Blend Window must be programmed to be either equal or within the Overlay Window.

15.4.12.1. AWINPOS—Alpha Blend Window Position Register

Memory Address Offset:

 

70h (R/W)

 

 

 

 

 

 

On-chip Reg. Mem Addr Offset:

30170h (RO; debug path)

 

 

 

 

Default Value:

 

00h

 

 

 

 

 

 

Access:

 

 

see address offset above

 

 

 

 

Size:

 

 

32 bits

 

 

 

 

 

 

31

27

26

16

15

11

10

0

 

 

 

 

Reserved

Alpha Blend Vertical top

 

Reserved

 

Alpha Blend Horizontal

 

 

 

 

 

 

line

 

 

 

left pixel

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Bit

 

 

 

Description

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

31:27

Reserved.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

26:16

Alpha Blend Vertical top line. Determines where on the display screen coordinates the overlay

 

 

 

 

 

display are alpha blended.

 

 

 

 

 

 

 

 

 

 

Alpha Blend Vertical Top in lines 0 = begin at display first line

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

15:11

Reserved.

 

 

 

 

 

 

 

 

 

 

 

 

 

10:0

Alpha Blend Horizontal left pixel. Determines where on the display screen coordinates the overlay

 

 

 

 

display are alpha blended.

 

 

 

 

 

 

 

 

 

 

Alpha Blend Horizontal Left in pixels 0 = begin at display left edge

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

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Image 298
Intel 815 manual Overlay Alpha Blend Window Position/Size Registers, AWINPOS-Alpha Blend Window Position Register