Renesas SH7781 - Manual (Page 982)

19. Display Unit (DU)
Rev.1.00 Jan. 10, 2008 Page 952 of 1658
REJ09B0261-0100
19.4.14 Upper-Left Overflow Display
For each plane, a display start position in memory (PnSPXR, PnSPYR) and display size
(PnDSXR, PnDSYR) can be set arbitrarily, so that by combining and using these registers, areas
overflowing the upper-left relative to the monitor origin (upper-left corner) can be displayed
without overwriting display data in memory.
For a picture of size (DSX, DSY) and with start position (SPX, SPY), by setting the size to (DSX-
ΔX, DSY-ΔY) and the start position to (SPX+ΔX, SPY+ΔY), the ΔX part overflowing on the left
side and the
ΔY part overflowing on top can be displayed. At this time, the display position
(PnDPXR, PnDPYR) is fixed at 0.
SPY
SPX
DSY
DSX
Monitor
SPY + ΔY
SPX + ΔX DSY - ΔY
DSX - ΔX
Monitor
DSX
DSY
DSY - ΔY
DSX - ΔX
ΔY
ΔX
Display data in memory Monitor screen
(DPX,DPY)=(0,0)
(DPX,DPY)=(0,0)
Display area start address
Monitor origin
Overflow display
Figure 19.11 Schematic Diagram of Upper-Left Overflow Display