Example 4: Generating a Boot Table for LP Core Devices
C-18
The sections that the compiler creates are divided into two categories: initial-
ized sections (sections that contain data or code) and uninitialized sections
(sections that reserve space but contain no actual data). Initialized sections
created by the TMS320C54x C compiler include .text, .cinit, .const, and .data.
Uninitialized sections are ignored by the hex conversion utility and are not
converted.
Most applications require that .text and .cinit sections are included in the boot.
This allows code and information for the C boot routine (c_int00 defined in
boot.asm) to load and run, initializing the C environment and branching to the
main function in the applications code.
The .cinit section contains the initialization data and tables for all global or
static C symbols that were declared with an initial value (i.e. int x = 5; ). Note
that the linker handles the .cinit section differently than the other sections.
When the linker encounters a .cinit section specified as an
output section in
the link, it automatically:
-
Sets the symbol cinit to point to the start of the included .cinit section
-
Appends a single word to the end of the section
This last word contains a zero that is used to mark the end of the initialization
table. However, if .cinit is included as an
input section only, the linker sets cinit
to –1, indicating that no initialization tables were loaded. Therefore, the C boot
routine, c_int00, does not attempt to initialize any of the global or static C
symbols.
When linking the .cinit section into an output section other than .cinit, the linker
does not perform the automatic functions listed above. Therefore, these func-
tions must be implemented explicitly within the linker command file.
Example C–14 shows a linker command file for a ’C54xLP device.
Summary of Contents for TMS320C54x
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