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NXP Semiconductors
PNX15xx/952x Series
Volume 1 of 1
Chapter 20: 2D Drawing Engine
PNX15XX_PNX952X_SER_N_4
NXP B.V. 2007. All rights reserved.
Product data sheet
Rev. 4.0 — 03 December 2007
20-634
When Depth is 16, PFormat[3] enables dithering the results of an alpha blend
operation. All alpha blend operations are done with 8 bits of precision for each
component. The components of the source pixels are expanded to 8 bits by
replicating the high-order bits into the low-order bits. The results of the computations
can be thought of as being in xed point, with 3, 4, 5 or 6 bits of precision to the left of
the decimal point, depending on the component and color format. When dithering is
enabled, a 4x4 dither is applied by adding a constant fraction to each component and
truncating the results to t in the resulting pixel. The constant fraction is taken from
the following table, based on the X and Y coordinates of the destination pixel.
This register is used to load the linear source address for a BLT operation.
It must be loaded with a pixel aligned address. Note that loading the SrcXY register
actually causes this register to be loaded with the proper linear pixel address.
This register is interpreted as a byte address, except during a monochrome host to
screen bit BLT, or a 4-bit or 8-bit expand alpha BLT. In the monochrome BLT case,
Adr[4:0] species the rst valid bit within the rst DWORD transferred by the host.
Adr[4:3] species the correct byte and Adr[2:0] specify the correct bit. In the 4-bit
expand case, Adr[3:0] species the rst valid nibble within the alpha data transferred
by the host. In the 8-bit expand case, Adr[2:0] species the rst valid byte within the
alpha data transferred by the host. This register is unchanged by drawing operations.
Table 12: Dithering
Format
X mod 4 = 0
X mod 4 = 1
X mod 4 = 2
X mod 4 = 3
Y mod 4 = 0
7/8
3/8
1/8
5/8
Y mod 4 = 1
1/8
5/8
7/8
3/8
Y mod 4 = 2
5/8
7/8
3/8
1/8
Y mod 4 = 3
3/8
1/8
5/8
7/8
Table 13: Source Linear
Bit
Symbol
Acces
s
Value
Description
Offset 0x04 F40C
Source Linear
31:24
Reserved
23:16
Adr[22:16]
R/W
-
Used to load the linear source address for a BLT operation.
15:8
Adr[15:8]
R/W
-
7:0
Adr[7:0]
R/W
-
Table 14: Destination Linear
Bit
Symbol
Acces
s
Value
Description
Offset 0x04 F410
Destination Linear
31:24
Reserved
23:16
Adr[22:16]
R/W
0
Used to load the starting linear pixel address for a vector or the
destination linear address for a BLT operation.
15:8
Adr[15:8]
R/W
0
7:0
Adr[7:0]
R/W
0