Analog Devices VisualDSP++ 5.0 Service Manual page 270

Theory of Operation
6
Figure 6-4. Selecting a 16 x 8 Block of Data From a Video Frame of
Size N x M
To select each row of the 16 x 8 block, the inner loop of the required 2-D
DMA configuration has 16 values (
The outer loop comprises 8 values (
N-15 (A + B in
jump from the end of one row to the start of the next.
It is also possible to extract interleaved data (for example, RGB values for
a video frame) by modifying both the x and y
to receive a stream of R,G,B,R,G,B,... values from an N x M frame,
consider Figure
6-30
6
16
data
B
Figure 6-4) chosen to instruct the DMA controller to
6-5.
VisualDSP++ 5.0 Device Drivers and System
N
8
) and a stride (
XCOUNT=16
) and a stride (
YCOUNT=8
modify
Services Manual for Blackfin Processors
A
M
frame
) of 1.
XMODIFY
) of
YMODIFY
values. For example,