Inter-Overlay Calls; Inter-Processor Calls - Analog Devices VisualDSP++ 3.5 Manual

Memory Management Using Overlays
When the reference and the definition reside in the same executable file,
the linker does not generate PLIT code. However, you can force the linker
to output a PLIT, even when all references can be resolved locally. The
command sets up data for the overlay manager, which first loads the
.plit
overlay that defines the desired symbol, and then branches to that symbol.

Inter-Overlay Calls

PLITs allow you to resolve inter-overlay calls, as shown in
page 5-25. Structure the
generated for inter-overlay function references is part of the
for , which is stored in non-overlay memory.
main()
L
Always store the
The linker resolves all references to variables in overlays, and the PLIT
allows an overlay manager to handle the overhead of loading and unload-
ing overlays.
Placing global variables in non-overlay memory optimizes overlays. This
action ensures that the proper overlay is loaded before a global variable is
called.

Inter-Processor Calls

PLITs resolve inter-processor overlay calls, as shown in
tems that permit one processor to access the memory of another processor.
When one processor calls into another processor's overlay, the call
increases the size of the
the overlay.
5-24
file in a way that ensures the PLIT code
.LDF
section in non-overlay memory.
.plit
section in the executable file that manages
.plit
VisualDSP++ 3.5 Linker and Utilities Manual
Figure 5-4 on
section
.plit
Figure 5-5, for sys-
for 16-Bit Processors