Using Plit{} And Overlay Manager - Analog Devices VisualDSP++ 3.5 Manual

Memory Management Using Overlays
L
The overlay managers in these examples are used universally. Spe-
cific applications may require some modifications, which may let
you eliminate of some instructions. For instance, if your applica-
tion allows the free use of registers, you may not need a run-time
stack.

Using PLIT{} and Overlay Manager

The command inserts assembly instructions that handle calls to
PLIT{}
functions in overlays. The instructions are specific to an overlay and are
executed each time a call to a function in that overlay is detected.
Refer to "PLIT{}" on page 3-38
"Introduction to Memory Overlays" on page 5-5
on overlays.
Figure 5-3 shows the interaction between a PLIT and an overlay manager.
To make this kind of interaction possible, the linker generates special sym-
bols for overlays. These overlay symbols are:
•
_ov_startaddress_#
•
_ov_endaddress_#
•
_ov_size_#
•
_ov_word_size_run_#
•
_ov_word_size_live_#
•
_ov_runtimestartaddress_#
The indicates the overlay number.
#
L
Overlay numbers start at 1 (not 0) to avoid confusion when these
elements are placed into an array or buffer used by an overlay
manager.
5-22
for basic syntax information. Refer to
VisualDSP++ 3.5 Linker and Utilities Manual
for detailed information
for 16-Bit Processors