Texas Instruments TMS320C54x, User Manual

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Overlay Pages
7-51 Linker Description
Within a page, you can bind output sections or use named memory areas in
the usual way. In Example 7–11, S1 could have been allocated:
S1 : load = 01200h, page = 1 { . . . }
This binds S1 at address 1200h in page 1. You can also use page as a qualifier
on the address. For example:
S1 : load = (01200h PAGE 1) { . . . }
If you do not specify any binding or named memory range for the section, the
linker allocates the section into the page wherever it can (just as it normally
does with a single memory space). For example, S2 could also be specified
as:
S2 : PAGE 2 { . . . }
Because OVR_MEM is the only memory on page 2, it is not necessary (but
acceptable) to specify = OVR_MEM for the section.
7.11.3 Page Definition Syntax
To specify overlay pages as illustrated in Example 7–10 and Example 7–11,
use the following syntax for the MEMORY directive:
MEMORY
{
PAGE 0 : name 1 [(attr)] : origin = constant , length = constant;
PAGE n : name n [(attr)] : origin = constant , length = constant;
}
Each page is introduced by the keyword PAGE and a page number, followed
by a colon and a list of memory ranges the page contains. Bold portions must
be entered as shown. Memory ranges are specified in the normal way. You can
define up to 255 overlay pages.
Because each page represents a completely independent address space,
memory ranges on different pages can have the same name. Configured
memory on any page can overlap configured memory on any other page.
Within a single page, however, all memory ranges must have unique names
and must not overlap.