macro language, assembly language, system programming chapter 3

1. MACROS
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2. MACRO
 Macro instructions are single-line abbreviations for group of
instructions.
 Macro is an abbreviation for a sequence of operations .
 Syntax/structure
start of definition MACRO
macro name {
Sequence to be abbreviated }
End of definition MEND
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3. MACRO
 Example
:
:
A 1, DATA
A 2, DATA
:
A 1, DATA
A 2, DATA
:
DATA DC F’5’ 11/15/2016jaya
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4. MACRO
 Example(Macro definition)
Syntax example
MACRO MACRO
MACRO NAME INCR
INSTRUCTION 1 A 1, DATA
INSTRUCTION 2 A 2, DATA
.
.
.
MEND MEND
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5. MACRO Example(Macro call)
Macro call(SYNTAX) macro call(example)
MACRO MACRO
MACRO NAME INCR
INSTRUCTION 1 A 1, DATA
INSTRUCTION 2 A 2, DATA
:
:
MEND MEND
:
INSTRUCTION A 3, DATA
:
MACRO NAME INCR
: DATA DC F’5
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6. MACRO
 Example(Macro definition)
Syntax example
MACRO MACRO
MACRO NAME INCR
INSTRUCTION 1 A 1, DATA
INSTRUCTION 2 A 2, DATA
.
.
.
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7. CONDITIONAL MACRO EXPANSION
 Two pseudo-ops are used
 AIF:- It is conditional branch pseudo-op that performs an
arithmetic test and branches to specified macro-label only if test is
true.
 AGO:- It is unconditional branch pseudo-op. It is equivalent to go-
to statement.
 .FINI:- Labels starting with a period(.), such as .FINI, are macro
label do not appear in the output of the macro processor.
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8. MACRO
: macro definition :
LOOP1 A 1,DATA1 MACRO
A 2,DATA2 ARG0 VARY &COUNT,&ARG1,&ARG2,&ARG3
A 3,DATA3 &ARG0 A 1,&ARG1
: AIF (&COUNT EQ 1).FINI
LOOP2 A 1,DATA3 A 2,&ARG2
A 2,DATA2 AIF (&COUNT EQ 2).FINI
: A 3,&ARG3
LOOP3 A 1,DATA1 .FINI MEND
: macro call :
DATA1 DC F’5’ LOOP1 VARY 3,DATA1,DATA2,DATA3
DATA2 DC F’10’ :
DATA3 DC F’15’ LOOP2 VARY 2,DATA3,DATA2
: :
LOOP3 VARY 1,DATA1
:
DATA1 DC F’5’
DATA2 DC F’10’
DATA3 DC F’15’
Pgm with macro definition
(macro call)
example
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9. MACRO
: :
MACRO MACRO
&ARG0 VARY &COUNT,&ARG1,&ARG2,&ARG3 &ARGO VARY &COUNT,&ARG1,&ARG2,&ARG3
&ARG0 A 1,&ARG1 &ARG0 A 1,&ARG1
AIF (&COUNT EQ 1).FINI AIF (&COUNT EQ 1).FINI
A 2,&ARG2 A 2,&ARG2
AIF (&COUNT EQ 2).FINI AIF (&COUNT EQ 2).FINI
A 3,&ARG3 A 3.&ARG3
.FINI MEND .FINI MEND 3,&ARG3
: :
LOOP1 VARY 3,DATA1,DATA2,DATA3 LOOP1 A 1,DATA1
: A 2,DATA2
LOOP2 VARY 2,DATA3,DATA2 A 3,DATA3
: :
LOOP3 VARY 1,DATA1 LOOP2 A 1,DATA3
: A 2,DATA2
DATA1DC F’5’ :
DATA2DC F’10’ LOOP3 A 1,DATA1
DATA3DC F’15’ :
Macro call
Macro expansion
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10. MACRO CALLS WITHIN MACROS
:
L 1,DATA1
A 1,=F’1’
ST 1,DATA1
L 1,DATA2
A 1,=F’1’
ST 1,DATA2
L 1,DATA3
A 1,=F’1’
ST 1,DATA3
:
:
DATA1 DC F’5’
DATA2 DC F’10’
DATA3 DC F’15’
:
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11. MACRO CALLS WITHIN MACROS
MACRO
ADD1 &ARG
L 1,&ARG
A 1,=F’1’
ST 1,&ARG
MEND
MACRO
ADDS &ARG1,&ARG2,&ARG3
ADD1 &ARG1
ADD1 &ARG2
ADD1 &ARG3
MEND
Macro call
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12. MACRO EXPANSION
SOURCE
:
MACRO
ADD1 &ARG
L 1,&ARG
A 1,=F’1’
ST 1,&ARG
MEND
MACRO
ADDS &ARG1,&ARG2,
&ARG3
ADD1 &ARG1 : :
ADD1 &ARG2
ADD1 &ARG3 L 1,DATA1
: ADD1 DATA1 A 1,=F’1’
: ST 1,DATA1
: L 1,DATA2
: ADD1 DATA2 A 1,=F’1’
ADDS DATA1,DATA2, ST 1,DATA2
DATA3 ADD1 DATA3 L 1,DATA3
A 1,=F’1’
: ST 1,DATA3
:
:
: :
: :
DATA1 DC F’5’ DATA1 DC F’5’
DATA2 DC F’10’ DATA2 DC F’10’
DATA3 DC F’15’ DATA3 DC F’15’
Expanded
source of
ADDS
Expanded
source of
ADD1
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13. MACRO DEFINITION WITHIN MACRO DEFINITION
MACRO
DEFINE &SUB
MACRO
&SUB &Y
CNOP 0,4
BAL 1,*+8
DC A(&Y)
L 15,=V(&SUB)
BALR 14,15
MEND
MEND
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14. MACRO DEFINITION WITHIN MACRO
DEFINITION
 Inner macro will not be defined until outer macro is called.
 Macro call sequence
 DEFINE COS
 The statement expands into a new macro definition
 COS AR
 The macro processor will generate the calling sequence:
BAL 1,*+8
DC A(AR)
L 15,=V(COS)
BALR 14,15
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15. IMPLEMENTATION
STATEMENT OF PROBLEM
SPECIFICATION OF DATA BASES
SPECIFICATION OF DATA BASE FORMAT
ALGORITHM
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16. STATEMENT OF PROBLEM
 Macro processor is a system program which accepts an assembly
language program with macro definition and macro calls and produce
an equivalent assembly language program in which all macro calls are
expanded.
 Four basic tasks of macro instruction processor
 Recognize macro definitions
 Save the definition
 Recognize calls
 Expand calls and substitute arguments
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17. STATEMENT OF PROBLEM
 Macro processor performs expansion using 2 passes
 Pass I
 It examines every operation code
 Save all macro definitions in a macro definition table
and macro name table
 Save a copy of the input text , minus macro definition
 Pass II
 Identify macro calls
 Replace each macro name with the appropriate text
from macro definition(expand macro call)
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18. SPECIFICATION OF DATA BASE
 PASS I
 The input macro source deck
 Output macro source deck copy for use by pass2
 Macro Definition Table(MDT)
 Macro Name Table(MNT)
 Macro Definition Table Counter(MDNTC)
 Macro Name Table Counter(MNTC)
 Argument List Array(ALA)
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19. SPECIFICATION OF DATA BASE
 PASS II
 The copy input macro source deck
 Output expanded source deck copy for use by
assembler
 Macro Definition Table(MDT) created by pass1
 Macro Name Table(MNT) created by pass1
 Macro Definition Table Pointer(MDNTP)
 Argument List Array(ALA)
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20. PASS 1- PROCESSING MACRO
DEFINITIONS
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21. EXAMPLE
MACRO
&LAB INCR &ARG1,&ARG2,&ARG3
&LAB A 1,&ARG1
A 2,&ARG2
A 3,&ARG3
MEND
|
|
INCR
Index Contents(80 bytes per entry)
5 &LAB INCR &ARG1,&ARG2,&ARG3
6 #0 A 2,#1
7 A 3,#2
8 A 2,#3
9 MEND
10
INDEX NAME(8
bytes)
0 #0(&LAB)
1 #1(&ARG1)
2 #2(&ARG2)
3 #3(&ARG3)
INDEX NAME( 8
bytes
MDT
POSITION(
4 bytes)
1 INCR 5
2
3
Macro Definition Table
Argument List Array
Macro Name Table
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22. PASS 2 – PROCESSING MACRO CALLS AND EXPANSION
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23. EXAMPLE
MACRO
&LAB INCR &ARG1,&ARG2,&ARG3
&LAB A 1,&ARG1
A 2,&ARG2
A 3,&ARG3
MEND
|
|
LOOP1 INCR DATA1,DATA2,DATA3
Index Contents ( 80 bytes per entry)
5 &LAB INCR &ARG1,&ARG2,&ARG3
6 #0 A 2,#1
7 A 3,#2
8 A 2,#3
9 MEND
10
INDEX NAME (
8 bytes)
0 “LOOP1bbb”
1 “DATA1bbb”
2 “DATA2bbb”
3 “DATA3bbb”
INDEX NAME ( 8 bytes) MDT
POSITION
( 4 byte)
1 “INCRbbb” 5
2
3
Macro Definition Table
Argument List Array
Macro Name Table
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24. MACRO
&LAB INCR &ARG1,&ARG2,&ARG3
&LAB A 1,&ARG1
A 2,&ARG2
A 3,&ARG3
MEND
|
|
LOOP1 INCR DATA1,DATA2,DATA3
LOOP1 A 1,DATA1
A 2, DATA2
A 3,DATA3
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25. IMPLEMENTATION OF MACRO
CALL WITHIN MACRO
 Basic problem in implementing macro calls within
macros is “recursion”
 Need to expand both macro
 Each call might be expanded by another macro
 More macros vs single macro
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26.  Example with 2 macros ADDS and ADD1
MACRO
ADD1 &ARG
L 1,&ARG
A 1,=F’1’
ST 1,&ARG
MEND
MACRO
ADDS &ARG1,&ARG2,&ARG3
ADD1 &ARG1
ADD2 &ARG2
ADD3 &ARG3
MEND
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27.  MDT(Macro Definition Table)
Index Contents
1 ADD1 &ARG
2 L 1,#1
3 A 1,=F’1’
4 ST 1,#1
5 MEND
6 ADDS &ARG1,&ARG2,&ARG3
7 ADD1 #1
8 ADD2 #2
9 ADD3 #3
10 MEND
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28. IMPLEMENTATION WITHIN AN
ASSEMBLER
 Macro processor can be added as a pre-processor to
an assembler
 Combining similar functions
 Ex- MNT+MOT/POT
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29. MACRO PROCESSOR COMBINED WITH
ASSEMBLER PASS 1
PASS 1!
Search Pseudo-Op Table
(POT)!
Search Macro Name Table
(MNT)!!
GO TO PASS2!
Search Machine -Op Table
(MOT)!
Process machine instruction
Type?
Process macro definition
Set up macro stack frame ,
etc.
Process pseudo-ops
READ *R
R
R
R R
END pseudo-op
Found
others
Not macro call
Not pseudo op
Found macro call
Macro pseudo op
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30. ADVANTAGES & DISADVANTAGES
OF INCORPORATING MACRO INTO
PASS1
 Advantages
 functions do not have to implemented twice
 Less overhead during processing
 More flexible for programmer
 Disadvantages
 Large program
 More complex
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31. SINGLE PASS ALGORITHM
 Problem of macro definition with macros
 Combine pass1 and pass2
 Two additional variables
 MDI(Macro Definition Input) indicator
 MDLC(Macro Definition Level Counter)
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32. One-pass macro processor
MDTC  1
MNTC  1
MDI  “OFF”
MDLC  0
Search MNT for match with
operation code
MDTP  MDT index from MNT
entry
READ
Macr
o
name
found
MDI  “ON”
Set up macro call argument list array
Macr
o
pseu
do-op
?
READ*
Enter macro name & current value of
MDTC in MNT entry number MNTC
MNTC  MNTC+1
Prepare macro definition argument list
array
Enter macro name card into MDT
MDTC MDTC+1
MDLC MDLC+1
READ*
MDTC MDTC+1
Substitute index notation for argument
in definition
Enter line into MDT
Macro
pseudo
-op ?
MEN
D
pseud
o-op ?
MDLC MDLC+1
MDLC MDLC-1
MDLC
 0 ?
MNTC  MNTC+1
END
Pseudo
-op?
Supply expanded source file to
processing
a
a
a
no
Yes macro call
no
no
yes
yes
no
yes
no
yes
no
Yes macro definition

33. READ *
subroutine
MDI =
“OFF”
?
Read next source card from
input file
Return to main processing
Increment MDT pointer to
next entry MDTP 
MDTP + 1
MDI  “OFF”
Get next card from MDT
Substitute arguments from
macro call
Process AIF or AGO set new value
to MDTP
MDLC
= 0 ?
MEND
pseudo-
op ?
AIF
or
AGO
?
yes
yes
yes
yes
No within
macro call
no
no
no
Detail of read function used
for macro expansion
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34. One-pass macro processor
MDTC  1
MNTC  1
MDI  “OFF”
MDLC  0
Search MNT for match with
operation code
SP  SP+N+2
READ
Macr
o
name
found
S(SP+N+2) SP
Set up macro call argument list
array in S(SP+2)---- S(SP+N+1)
where N = total number of
arguments
Macr
o
pseu
do-
op ?
READ*
Enter macro name & current value of
MDTC in MNT entry number MNTC
Prepare macro definition argument list
array
Enter macro name card into MDT
MDLC MDLC+1
READ*
Substitute index notation for
argument in definition
Enter line into MDT
Macro
pseudo
-op ?
MEN
D
pseud
o-op ?
MDLC MDLC+1
MDLC MDLC-1
MDLC
 0 ?
MNTC  MNTC+1
END
Pseudo
-op?
Supply expanded source file to
processing
a
a
a
no
Yes macro call
no
no
yes
yes
no
yes
no
yes
no
Yes macro definition
S(SP+1) MDT index from MNT
entry
b
b
b
One pass macro processor capable
of handling macro calls within macro
definitions
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35. READ *
subroutine
SP = -
1
Read next source card from
input file
Return to main processing
Increment MDT pointer to
next entry S(SP+1)+1
Get next card from MDT ;
pointer is S(SP+1)
Substitute arguments from macro
call S(SP+2)…S(SP+N+1)
N  SP – S(SP)-2
AIF or
AGO ? MEND
pseudo-
op ?
MDL
C = 0
?
yes
yes
yes
No within
macro call
no
no
yes
Process AIF or AGO set new value
to MDTP
SP  S(SP)
yes
no
b
b
Detail of read
function for
recursive
macro
expansion
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