AMD Geode LX 600@0.7W Data Book page 444

33234H
Bit Name
16 ALPHA2_WIN_
EN
15:8 ALPHA2_INC
7:0 ALPHA2_MUL
6.8.3.31 Alpha Window 3 X Position (A3X)
VP Memory Offset 100h
Type R/W
Reset Value 00000000_00000000h
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
31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16 15 14 13 12 11 10
RSVD
Bit Name
63:28 RSVD (RO)
27:16 ALPHA3_X_
END
15:12 RSVD (RO)
11:0 ALPHA3_X_
START
Note 1. H_TOTAL and H_SYNC_END are values programmed in the Display Controller module registers.
The value of (H_TOTAL – H_SYNC_END) is sometimes referred to as "horizontal back porch."
444
A2T Bit Descriptions (Continued)
Description
Alpha Window 2 Enable. Enable bit for alpha window 2.
0: Disable alpha window 2.
1: Enable alpha window 2.
Alpha Window 2 Increment. Specifies the alpha value increment/decrement. This is a
signed 8-bit value that is added to the alpha value for each frame. The MSB (bit 15) indi-
cates the sign (i.e., increment or decrement). When this value reaches either the maxi-
mum or the minimum alpha value (255 or 0) it keeps that value (i.e., it is not incremented/
decremented) until it is reloaded via LOAD_ALPHA (bit 17).
Alpha Window 2 Value. Specifies the alpha value to be used for this window.
A3X Register Map
ALPHA3_X_END
A3X Bit Descriptions
Description
Reserved (Read Only). Reads back as 0.
Alpha Window 3 X End. Indicates the horizontal end position of alpha window 3. This
value is calculated according to the following formula:
Value = Desired screen position + (H_TOTAL – H_SYNC_END) – 1. (Note 1)
Reserved (Read Only). Reads back as 0.
Alpha Window 3 X Start. Indicates the horizontal start position of alpha window 3. This
value is calculated according to the following formula:
Value = Desired screen position + (H_TOTAL – H_SYNC_END) – 2. (Note 1)
Video Processor Register Descriptions
RSVD
RSVD
AMD Geode™ LX Processors Data Book
9 8 7 6 5 4 3 2
ALPHA3_X_START
1 0