PXD20RM Datasheet, PDF (423/1628 Pages) Freescale Semiconductor, Inc – PXD20 Microcontroller

output_val = output_val >>7;
if ((output_val & 0x1) == 0x1))
output_val = output_val + 0x2;
output_val = output_val >> 1;
The blend can apply to pixels with no alpha channel (RGB) or with an alpha channel (ARGB) in different
ways.
Table 11-72 defines how the settings of the BB and AB bit fields affect the pixels in the layer; RGB formats
are RGB565, and RGB888; ARGB formats are 1 bpp, 2 bpp, 4 bpp, 8 bpp, APAL8, ARGB1555,
ARGB4444, and BGRA8888. Pixels in YCbCr format are treated as RGB pixels for the purposes of the
blend.
Table 11-72. Blend options for BB and AB configurations
Case
BB
1
0
2
1
3
0
4
1
5
0
6
1
7
0
8
1
9
0
10
1
11
0
12
1
13
0
14
1
15
0
16
1
AB
Format
Function
00
RGB No blending, underlying pixels are obscured
00
RGB Selected pixels are completely removed
01
RGB The value in TRANS becomes the alpha channel of all pixels
on the layer
01
RGB The value in TRANS becomes the alpha channel of the
selected pixels on the layer
10
RGB Same as case 3
10
RGB Selected pixels are completely removed and the value in
TRANS becomes the alpha channel of the non-selected pixels
on the layer
11
RGB Reserved
11
RGB Reserved
00
ARGB No blending, pixel alpha is ignored and underlying pixels are
obscured
00
ARGB Selected pixels are completely removed, pixel alpha is ignored
01
ARGB Pixel alpha is used to blend layer with underlying pixels. Value
in TRANS is ignored.
01
ARGB Uses the pixel alpha of the selected pixels only to blend layer
with underlying pixels. Value in TRANS is ignored.
10
ARGB The value in TRANS is multiplied with the pixel alpha value and
the resultant alpha is used to blend all the pixels
10
ARGB Selected pixels are completely removed, the value in TRANS
is multiplied with the pixel alpha value and the resultant alpha
is used to blend the non-selected pixels on the layer
11
ARGB Reserved
11
ARGB Reserved
Freescale Semiconductor
PXD20 Microcontroller Reference Manual, Rev. 1
Preliminary—Subject to Change Without Notice
11-89