Texas Instruments TMS320C54x User Manual page 176

Syntax
Description
symbol .usect " section name " , size in words [, [ blocking flag ] [, alignment flag ]]
The .usect directive reserves space for variables in an uninitialized, named
section. This directive is similar to the .bss directive; both simply reserve space
for data and have no contents. However, .usect defines additional sections
that can be placed anywhere in memory, independently of the .bss section.
symbol
points to the first location reserved by this invocation of the
.usect directive. The symbol corresponds to the name of
the variable for which you're reserving space.
section name must be enclosed in double quotes. This parameter
names the uninitialized section. The name can be up to
200 characters. For COFF1 formatted files, only the first
8 characters are significant. A section name can contain
a subsection name in the form section name : subsection
name .
size in words is an expression that defines the number of words that are
reserved in section name.
blocking flag
is an optional parameter. If specified and nonzero, the flag
means that this section will be blocked. Blocking is an ad-
dress mechanism similar to alignment, but weaker. It
means a section is guaranteed to not cross a page bound-
ary (128 words) if it is smaller than a page, and to start on
a page boundary if it is larger than a page. This blocking
applies to the section, not to the object declared with this
instance of the .usect directive.
alignment flag is an optional parameter. This flag causes the assembler
to allocate size on long word boundaries.
Note: Specifying an Alignment Flag Only
To specify an alignment flag without a blocking flag, you must insert two com-
mas before the alignment flag, as shown in the syntax.
Other sections directives (.text, .data, and .sect) end the current section and
tell the assembler to begin assembling into another section. The .usect and the
.bss directives, however, do not affect the current section. The assembler as-
sembles the .usect and the .bss directives and then resumes assembling into
the current section.
Variables that can be located contiguously in memory can be defined in the
same specified section; to do so, repeat the .usect directive with the same sec-
tion name.
Reserve Uninitialized Space
Assembler Directives
.usect
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