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AMD Geode™ LX Processors Data Book 341
Display Controller Register Descriptions
33234H
6.6.10 Graphics Scaling Control Registers
6.6.10.1 DC Graphics Filter Scale (DC_GFX_SCALE)
DC Memory Offset 090h
Typ e R /W
Reset Value 40004000h
DC_GFX_SCALE Register Map
313029282726252423222120191817161514131211109876543210
V_SCALE H_SCALE
DC_GFX_SCALE Bit Descriptions
Bit Name Description
31:16 V_SCALE Vertical Filter Scale. The value in this field, represents the number of vertical lines of
source data that are consumed for every line of filtered data produced by the scaler filter.
This field is treated as a rational number, with the decimal point between bits 30 and 29.
To determine the value to be programmed into this field, use the following formula:
V_SCALE = (V_SOURCE / (V_DEST-1)) << 14
Where V_SOURCE is the height (in scan lines) of the frame buffer and V_DEST is the
height (in scan lines) of the destination field.
The default value of this field (4000h) represents 1:1 scaling. This value must be pro-
grammed when the vertical filter is disabled.
The value in this field must not exceed 8000h, which represents a 2:1 downscale ratio. If
the width of the source image is more than 1024 pixels, scaling is not supported.
15:0 H_SCALE Horizontal Filter Scale. The value in this field, represents the number of (horizontal) pix-
els of source data that are consumed for every pixel of data produced by the scaler filter.
This field is treated as a rational number, with the decimal point between bits 14 and 13.
To determine the value to be programmed into this field, use the following formula:
H_SCALE = (H_SOURCE/(H_DEST-1)) << 14
Where H_SOURCE is the width (in pixels) of the frame buffer and H_DEST is the width
(in pixels) of the destination image.
The default value of this field (4000h) represents 1:1 scaling. This value must be pro-
grammed when the horizontal filter is disabled.
The value in this field must never exceed 8000h, which represents a 2:1 horizontal down-
scale. If the width of the source image is greater than 1024 pixels, scaling is not sup-
ported.