Allocating Space For Plits - Analog Devices VisualDSP++ 3.5 Manual

Advanced LDF Commands
After the setup and variable identification are completed, the overlay itself
is brought (via DMA transfer) into run-time memory. This process is con-
trolled by assembly code called an overlay manager .
The branch instruction, such as
the last instruction in the

Allocating Space for PLITs

The file must allocate space in memory to hold PLITs built by the
.LDF
linker. Typically, that memory resides in the program code memory seg-
ment. A typical LDF declaration for that purpose is:
// ... [In the SECTIONS command for Processor P0]
// Plit code is to reside and run in mem_program segment
.plit {} > mem_program
A command may appear in the global LDF scope, within a
PLIT{}
command or within a
PROCESSOR{}
• No input section is associated with the
LDF allocates space for linker-generated routines, which do not
contain (input) data objects.
• This segment allocation does not take any parameters. You write
the structure of this command according to the PLIT syntax. The
linker creates an instance of the command for each symbol that
resolves to an overlay. The linker stores each instance in the
output section, which becomes part of the program code's memory
segment.
5-36
jump OverlayManager
command.
PLIT{}
SECTIONS{}
VisualDSP++ 3.5 Linker and Utilities Manual
, is normally
command.
output section. The
.PLIT
for 16-Bit Processors
.PLIT