Writing Assembly Language Programs
Assembler Output
2-6
DSP ASSEMBLER REFERENCE MANUAL
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MOTOROLA
2.4.7
Comment Field
Comments are not considered significant to the Assembler, but can be included in the
source file for documentation purposes. A comment field is composed of any characters
(not part of a literal string) that are preceded by a semicolon (
;
). A comment starting in the
first column of the source file will be aligned with the label field in the listing file. Otherwise,
the comment will be shifted right and aligned with the comment field in the listing file, un-
less the
NOPP
option is used (see the
OPT
directive, Chapter 6). Comments preceded
by two consecutive semicolons (
;;
) will not be reproduced on the Assembler listing and
will not be saved as part of a macro definition.
2.5
ASSEMBLER OUTPUT
The Assembler output consists of an optional listing of the source program and an optional
object file. Appendix D contains the description of the source listing format and Appendix
E contains the description of the object file format.
The assembly source program listing contains the original source statements, formatted
for easier reading, as well as additional information which is generated by the Assembler.
Most lines in the listing correspond directly to a source statement. Lines which do not cor-
respond directly to source statements include page headings, error messages, and ex-
pansions of macro calls or directives such as
DC
(
D
efine
C
onstant; see Chapter 6).
The assembly listing optionally may contain a symbol table or a cross-reference table of
all non-local symbols appearing in the program. These are always printed after the end of
source input or the
END
directive (whichever occurs first) if either the symbol table or
cross-reference table options are in effect (see the
OPT
directive, Chapter 6). The symbol
table contains the name of each symbol, along with its defined value. The cross-reference
table additionally contains the Assembler-maintained source line number of every refer-
ence to every non-local symbol (local symbols may be included in the cross-reference list-
ing by using the
LOC
option; see the
OPT
directive, Chapter 6). The format of the cross-
reference table is shown in Appendix D.
If the
MU
option is enabled (see the
OPT
directive, Chapter 6), the Assembler generates
a report of load and runtime memory utilization. The report shows beginning and ending
addresses of allocated memory areas, along with their lengths and associated symbol
names, if applicable. A separate report is generated for each memory space where data
has been reserved for use by the program. The format of the report is given in Appendix D.
The Assembler object file is a binary COFF (Common Object File Format) file, with exten-
sions and adaptations to support symbolic debugging and to make DSP object files trans-
portable among host platforms. COFF is a formal definition for the structure of machine
code files. It is derived from AT&T UNIX System V and represents a quasi-de facto stan-
dard for object file formats. Refer to Appendix E for more information on Motorola DSP
COFF structure and layout.
F
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n
.