Motorola dsp assembler Reference Manual

Writing Assembly Language Programs
Source Statement Format
MOTOROLA
DSP ASSEMBLER REFERENCE MANUAL
2-5
2.4.3
  Operand Field
The interpretation of the operand field is dependent on the contents of the operation field.
The operand field, if present, must follow the operation field, and must be preceded by at
least one space or tab.  The operand field may contain a symbol, an expression, or a com-
bination of symbols and expressions separated by commas.  There should be no inter-
vening whitespace characters separating operand elements.
 
The operand field of machine instructions is used to specify the addressing mode of the
instruction, as well as the operand of the instruction. The format of the operand field for a
particular instruction is given in Appendix A of the User Manual for the DSP in question
(.e.g. DSP56000/DSP56001 User’s Manual). The operand fields of Assembler directives
are described in Chapter 6. The operand fields of macros (Chapter 5) depend on the def-
inition of the macro.
2.4.4
  Operation 2 Field
DSP96000 only.  The second operation field occurs after the first operand field, and only
in conjunction with an FMPY instruction.  The field must be preceded by at least one space
or tab.  The second operation field may consist only of the instructions FADD, FSUB, and
FADDSUB.
2.4.5
  Operand 2 Field
DSP96000 only.  The interpretation of the second operand field is dependent on the con-
tents of the second operation field.  The second operand field, if present, must follow the
second operation field, and must be preceded by at least one space or tab.  The operand
field may contain only those register combinations appropriate to the second operation
field.
The operand field of machine instructions is used to specify the addressing mode of the
instruction, as well as the operand of the instruction.  The format of the operand field for
each DSP96000 instruction is described in Appendix A of the DSP96002 User’s Manual.
2.4.6
  Data Transfer Fields
Most opcodes can specify one or more data transfers to occur during the execution of the
instruction.  These data transfers are indicated by two addressing mode operands sepa-
rated by a comma, with no embedded blanks.  If two data transfers are specified, they
must be separated by one or more blanks or  tabs.  See the appropriate DSP User’s Man-
ual for a complete discussion of addressing modes that are applicable to data transfer
specifications.

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Writing Assembly Language Programs
Assembler Output
2-6
DSP ASSEMBLER REFERENCE MANUAL
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 (Define Constant; 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.

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