The document outlines the design and functioning of a macro assembler, detailing its three passes: macro definition processing, macro expansion, and target code generation. It discusses the advantages such as reduced overhead and increased flexibility, while also mentioning drawbacks like potential size issues in combined pass 1 and complexity. Additionally, it compares single-pass and two-pass macro processors and describes the tables generated during macro processing.

1. BIRLA INSTITUE OF TECHNOLOGY,MESRA
JAIPUR CAMPUS
TOPIC : MACRO ASSEMBLER
BY
MEGHAJ KUMAR MALLICK
(MCA/25017/18)
MCA 2ND YEAR, 4TH SEMESTER

2. Design of a Macro Assembler

3. Design of Macro Assembler
• 3 passes in macro Assembler.
Pass 1:
– Macro definition processing.
– SYMTAB construction.
Pass 2:
– Macro expansion.
– Memory allocation & LC processing.
– Processing of Literals.
– Intermediate Code Generation.

4. pass 3:
– Target code Generation.
– Macro processor can be added asa
processor to an assembler.
– It is implemented in pass 1 of the
assembler.
Design of Macro AssembleR

5. Advantages:
– Many functions don’t have to be
implemented twice.
– Less overhead during processing.(by
removing intermediate code)
– More flexibility is available to the
programmer.
Design of Macro AssembleR

6. Disadvantages:
• Combined pass 1 of the assembler &
macro processor may be too large for a
program to fit into core of some
machine.
• Complexity of such program maybe
overwhelming.
Design of Macro AssembleR

7. PAPASSSPASS 1
R
SeSeararcchh
ppsseeuuddoo-o-oppTTablabl
Search
pseudo-op Table
SeSeararcchh
MMacacrroonnamamee TTaablbl
Search
Macro name Table
SeSeararcchh
mmaacchihinnee-o-opp TTbllee
Search
machine-op Table
GGoo ttoo
PAPASSS
S22
Go to
PASS 2Type ?
Process
Process
Pseudo-ops
Process
Machine instruction
Setup macro
stack frame ,etc.
READ
R
R
R
Maccro definition
Found, macro
calls R
Found
Not
Not
End
pseudo-op
Others
Macro
pseudo-op

8. Microsoft Macro Assembler
 MASM is an assembler for the x86 family of microprocessors,
originally produced MS-DOS operating system. The MASM is the
example of high level assembler. It supports following main
features-
i) A wide variety of macro facilities
ii) Structure programming idioms
iii)High level constructions for looping, procedure calls , and
alteration
The later versions of MASM added the capability of producing
program for the windows operating system. The example of this
type is MASM – 32 which work on the program which already
written API based code in windows .

9. Comparison of Macro Processors
Design
Single pass
 every macro must be defined before it is called
 one-pass processor can alternate between macro definition and
macro expansion
 nested macro definitions may be allowed but nested calls are
not
 Two pass
 Pass1: Recognize macro definitions
 Pass2: Recognize macro calls
 nested macro definitions are not allowed

10. Tables generated while macro
processing
The macro processing leads to generation of three
types of tables –
1. DEFTAB – the definition of the macro is stored in
this table.
2. NAMTAB – the name of the macro is stored in
this table.
3. ARGTAB – all the arguments of macro is stored
in this table.