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432 AMD Geode™ LX Processors Data Book
Video Processor Register Descriptions
33234H
6.8.3.15 Video Downscaler Control (VDC)
VXS Bit Descriptions
Bit Name Description
63:32 RSVD (RO) Reserved (Read Only). Reads back as 0.
31:20 X_ACC_INIT X Accumulator Initial Value. Load this value before each video line. Works with hori-
zontal scaling, in case a sub-pixel offset is required prior to displaying video. Pad 4 LSBs
with 0 when loading.
19:0 VID_X_SCL Video X Scale Factor. Bits [19:16] represent the integer part of horizontal scale factor of
the video window according to the following formula:
X_SCL_INT = 1/Xs
Where:
Xs = Arbitrary horizontal scaling factor.
Bits [5:0] represent the fractional part of horizontal scale factor of the video window
according to the following formula:
VID_X_SCL = FFFFh * 1/Xs
Note: If no scaling is intended, set to 10000h. Will be greater than 1000h when down-
scaling. Will be less than 10000h when upscaling.
VP Memory Offset 078h
Typ e R /W
Reset Value 00000000_00000000h
VDC Register Map
63 62 61 60 59 58 57 56 55 54 53 52 51 50 49 48 47 46 45 44 43 42 41 40 39 38 37 36 35 34 33 32
RSVD
313029282726252423222120191817161514131211109876543210
RSVD
DTS
RSVD
DFS
DCF
VDC Bit Descriptions
Bit Name Description
63:7 RSVD (RO) Reserved (Read Only). Reads back as 0.
6DTS Downscale Type Select.
0: Type A (downscale formula is 1/m + 1, m pixels are dropped, one pixel is kept).
1: Type B (downscale formula is m/m + 1, m pixels are kept, one pixel is dropped).
5 RSVD (RO) Reserved (Read Only). Reads back as 0.
4:1 DFS Downscale Factor Select. Determines the downscale factor to be programmed into
these bits, where m is used to derive the desired downscale factor depending on bit 6
(DTS). Only values up to 7 are valid.
0 DCF Downscaler and Filtering. Enables/disables downscaler and filtering logic.
0: Disable.
1: Enable.