Texas Instruments TMS320C54x User Manual page 31

The syntax for these directives is:
.bss symbol, size in words [, [ blocking flag ] [, alignment flag ]]
symbol .usect " section name " , size in words [, [ blocking flag ] [, alignment flag ]]
symbol
points to the first word reserved by this invocation of the .bss
or .usect directive. The symbol corresponds to the name of
the variable that you're reserving space for. It can be refer-
enced by any other section and can also be declared as a
global symbol (with the .global assembler directive).
size in words
is an absolute expression.
-
-
blocking flag is an optional parameter. If you specify a value greater than
0 for this parameter, the assembler associates size words
contiguously; the allocated space will not cross a page
boundary, unless size is greater than a page, in which case
the object will start on a page boundary.
alignment flag is an optional parameter. If you specify a value greater than
0 for this parameter, the section is aligned to a long word
boundary.
section name
tells the assembler which named section to reserve space
in. For more information about named sections, see
subsection 2.3.3, Named Sections , on page 2-7.
The .text, .data, and .sect directives tell the assembler to stop assembling into
the current section and begin assembling into the indicated section. The .bss
and .usect directives, however, do not end the current section and begin a new
one; they simply escape temporarily from the current section. The .bss and
.usect directives can appear anywhere in an initialized section without
affecting its contents.
Uninitialized subsections are created with the .usect directive. The assembler
treats uninitialized subsections in the same manner as uninitialized sections.
See subsection 2.3.4, Subsections , on page 2-8 for more information on
creating subsections.
How the Assembler Handles Sections
The .bss directive reserves size words in the .bss sec-
tion.
The .usect directive reserves size words in section
name.
Introduction to Common Object File Format 2-5