User's Manual

Intel® 815 Chipset: Graphics Controller PRM, Rev 1.0
R
55
The BLT engine can alter the order in which source data is read and destination data is written when
necessary to avoid source data corruption problems when the source and destination locations overlap.
The command packets provide the ability to change the point at which the BLT engine begins reading
and writing data from the upper left-hand corner (the usual starting point) to one of the other three
corners. The BLT engine may be set to read data from the source and write it to the destination starting at
any of the four corners of the panel.
Figure 10. Correctly Performed BLT with Overlapping Source and Destination Locations
(i)
Source
Destination
(a)
Source
Destination
b_blt3.vsd
(e)
(b)
(c)
(d)
(f)
(g)
(h)