Analog Devices VisualDSP++ 3.5 Manual page 229

Memory Overlays and Advanced LDF Commands
The two functions in
linker generates PLIT code only when an unresolved function reference is
resolved to a function definition in overlay memory.
Non-Overlay Memory
Overlay 1 Storage
Overlay 2 Storage
Run-time Overlay Memory
Figure 5-3. PLITs and Overlay Memory; main() Calls to Overlays
The function calls functions
main
lay memory. Because the linker cannot resolve these functions locally, the
linker replaces the symbols
references to
X
VisualDSP++ 3.5 Linker and Utilities Manual
for 16-Bit Processors
Figure 5-3 are on different overlays. By default, the
main()
{
int (*pf)() = X;
Y();
}
/* PLIT & overlay manager handle calls,
using the PLIT to resolve calls
and load overlays as needed */
.plt_X: call OM
.plt_Y: call OM
X() {...}
Y() {...}
and
X
and are resolved to
Y
// function X defined
// function Y defined
// currently loaded overlay
and , which are defined in over-
X() Y()
with and
Y .plit_X
and
.plit_X .plit_Y
. Unresolved
.plit_Y
.
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