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8/13/2019 Ss Unit 2 Notes
http://slidepdf.com/reader/full/ss-unit-2-notes 1/22
CS 2304 SYSTEM SOFTWARE G.PRABHAKARAN – AP/CSE
S.SELVARANI – AP/CSE
UNIT II ASSEMBLERS
Basi ass!"#$!% &'()i*(s
A si"+$! SIC ass!"#$!%
Ass!"#$!% a$,*%i)-" a( a)a s)%')'%!s
Ma-i(! !+!(!() ass!"#$!% &!a)'%!s
I(s)%')i*( &*%"a)s a( a%!ssi(, "*!s
P%*,%a" %!$*a)i*(
Ma-i(! i(!+!(!() ass!"#$!% &!a)'%!s
Li)!%a$s
S"#*$!&i(i(, s)a)!"!()s E1+%!ssi*(s
P%*,%a" #$*s
O(! +ass ass!"#$!%s a( M'$)i +ass ass!"#$!%s
I"+$!"!()a)i*( !1a"+$!s
MASM ass!"#$!%.
Assemblers1:
iT%a(s$a)i*( "(!"*(i *+!%a)i*( *!s )* )-!i% "a-i(! $a(,'a,! !5'i6a$!()s a(assi,(i(, "a-i(! a%!ss )* s"#*$i $a#!$s 's! # )-! +%*,%a""!%. iiT-!%! a%! s*"! &!a)'%!s *& a( ass!"#$!% $a(,'a,! )-a) -a6! (* i%!) %!$a)i*( )* "a-i(!
a%-i)!)'%!.
1. Basic Assembler Functions2:
STARTS+!i&i (a"! a( s)a%)i(, a%!ss &*% )-! +%*,%a".
EN7I(ia)! )-! !( *& )-! s*'%! +%*,%a" a( s+!i& )-! &i%s) !1!')a#$! i(s)%')i*( i()-! +%*,%a".
BYTEG!(!%a)! -a%a)!% *% -!1a!i"a$ *(s)a()8*'+i(, a( "a( #)!s as (!!! )*
%!+%!s!() )-! *(s)a().WOR7G!(!%a)! *(!9*% i()!,!% *(s)a().
RESBR!s!%6! )-! i(ia)! ('"#!% *& #)!s &*% a a)a a%!a.RESWR!s!%6! )-! i(ia)! ('"#!% *& 9*%s &*% a a)a a%!a.
2 MARKS
1.e!ine assembler.2. "#at are t#e basic !unctions in assembler. E$%lain.
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CS 2304 SYSTEM SOFTWARE G.PRABHAKARAN – AP/CSE
S.SELVARANI – AP/CSE
E$am%le: SIC assa"#$!% $a(,'a,! +%*,%a".
T-! +%*,%a" *()ai(s a "ai( %*')i(! )-a) %!as %!*%s &%*" a( i(+') !6i! a( *+i!s
)-!" )* a( *')+') !6i!.
T-is "ai( %*')i(! a$$s s'#%*')i(! R7REC )* %!a a %!*% i()* a #'&&!% a( s'#%*')i(!
WRREC )* 9%i)! )-! %!*% &%*" )-! #'&&!% )* )-! *')+') !6i!.
Ea- s'#%*')i(! "'s) )%a(s&!% )-! %!*% *(! -a%a)!% a) a )i"!.
B!a's! )-! *($ i(s)%')i*(s a6ai$a#$! a%! R7 a( W7.
T-! #'&&!% is (!!ssa% #!a's! )-! I/O %a)!s &*% )-! )9* !6i!s8s'- as a is a( a s$*9
+%i()i(, )!%"i(a$ "a #! 6!% i&&!%!(). T-! !( *& !a- %!*% is "a%! 9i)- a ('$$ -a%a)!%.I& a %!*% is $*(,!% )-a( )-! $!(,)-*& )-! #'&&!% 40;< #)!s8*($ )-! &i%s) 40;< #)!s a%! *+i!.
T-! +%*,%a" *!s (*) !a$ 9i)- !%%*% %!*6!%.
T-! !( *& )-! &i$! )* #! *+i! is i(ia)! # =!%*$!(,)- %!*%.
W-!( )-! !( *& &i$! is !)!)!8)-! +%*,%a" 9%i)!s EOF *( )-! *')+') !6i! a( )!%"i(a)!s# !1!')i(, RS:B i(s)%')i*(.
T-is +%*,%a" 9as a$$! # )-! *+!%a)i(, ss)!" 'si(, a >S:B i(s)%')i*(8T-'s )-! RS:B
9i$$ %!)'%( *()%*$ )* )-! *+!%a)i(, ss)!".
PROGRAME?PLANATION
LINE LOCCTR LABEL
SO:RCE STATEMENT
OPCO7E OPERAN7
@ COPY START 000 COPY FILE FROM I/P TO O/P
0 FIRST STL RETA7R SAVE RET:RN A77RESS
@ CLOOP >S:B R7REC REA7 I/P RECOR7
20 L7A LENGTH TEST FOR EOFLENGTH0
2@ COMP ERO
30 >ED EN7FIL E?IT IF EOF FO:N7
3@ >S:B WRREC WRITE O/P RECOR7
40 > CLOOP LOOP
4@ EN7FIL L7A EOF INSERT EN7 OF FILE MARKER
@0 STA B:FFER
@@ L7A THREE SET LENGTH3
<0 STA LENGTH
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CS 2304 SYSTEM SOFTWARE G.PRABHAKARAN – AP/CSE
S.SELVARANI – AP/CSE
<@ >S:B WRREC WRITE EOF
0 L7L RETA7R GET RET:RN A77RESS
@ RS:B RET:RN TO CALLER
0 EOF BYTE CEOF
@ THREE WOR7 3
;0 ERO WOR7 0
00 RETA7R RESW
0@ LENGTH RESW
0 B:FFER RESB 40;<
S:B RO:TINE TO REA7 RECOR7 INTO B:FFER
PROGRAME?PLANATION
LINE LOCCTR LABEL
SO:RCE STATEMENT
OPCO7E OPRAN7
2@ R7REC L7? ERO CLEAR LOOP CO:NTER
30 L7A ERO CLEAR A TO ERO
3@ RLOOP T7 INP:T TEST I/P 7EVICE
40 >ED RLOOP LOOP :NTIL REA7Y4@ R7 INP:T REA7 CHARACTER INTO
REGISTER A
@0 COMP ERO TEST FOR EN7 OF RECOR7
@@ >ED E?IT E?IT LOOP IF EOR
<0 STCH B:FFER8? STORE CHARACTER IN B:FFER
<@ TI? MA?LEN LOOP :NLESS MA? LENGTH HASBEEN REACHE7
0 >LT RLOOP@ E?IT ST? LENGTH SAVE RECOR7 LENGTH
0 RS:B RET:RN TO CALLER
@ INP:T BYTE ?F CO7E FOR I/P 7EVICE
;0 MA?LEN WOR7 40;<
S:BRO:TINE TO WRITE RECOR7 FROM B:FFER
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CS 2304 SYSTEM SOFTWARE G.PRABHAKARAN – AP/CSE
S.SELVARANI – AP/CSE
PROGRAM
E?PLANATION
LINE LOCCTR LABEL
SO:RCE STATEMENT
OPCO7E OPERAN7
200 WRREC L7? ERO CLEAR LOOP CO:NTER
20 WLOOP T7 O:TP:T TEST O:TP:T 7EVICE
2@ >ED WLOOP LOOP :NTIL REA7Y
220 L7CH B:FFER8? GET CHARACTER FROM B:FFER
22@ W7 O:TP:T WRITE CHARACTER
230 TI? LENGTH LOOP :NTIL ALL CHARACTERS
HAVE BEEN WRITTEN
23@ RS:B RET:RN TO CALLER
240 O:TP:T BYTE ?0@ CO7E FOR O/P 7EVICE
24@ EN7 FIRST
2. A Sim%le SI& Assembler:
C*(6!%) "(!"*(i *+!%a)i*( *!s )* )-!i% "a-i(! $a(,'a,! !5'i6a$!()s.!1a"$+!)%a(s$a)! STL )* 4
C*(6!%) s"#*$i *+!%a(s )* )-!i% !5'i6a$!() "a-i(! a%!ss!s.!1a"+$!)%a(s$a)!
RETA7R )* 033
B'i$ )-! "a-i(! i(s)%')i*(s i( )-! +%*+!% &*%"a).
C*(6!%) )-! a)a *(s)a()s s+!i&i! i( )-! s*'%! +%*,%a" i()* )-!i% i()!%(a$ "a-i(!
%!+%!s!()a)i*(s!1a"+$!EOF )* 4@4&4<
W%i)! )-! *#!) +%*,%a" a( )-! ass!"#$!%. C*(si!% )-! s)a)!"!()8
0 000 FIRST STL RETA7R
T* )%a(s$a)! )-! +%*,%a" $i(! # $i(!89! 9i$$ #! '(a#$! )* +%*!ss )-is s)a)!"!() #!a's! 9!* (*) (*9 )-! a%!ss )-a) 9i$$ #! assi,(! )* RETA7R.
B!a's! *& )-is8"*s) *& ass!"#$!%s "a! )9* +ass!s *6!% )-! s*'%! +%*,%a".
T-! &i%s) +ass *!s $i))$! "*%! )-a( sa( )-! s*'%! +%*,%a" &*% $a#!$ !&i(i)i*(s a( assi,(a%!ss!s.
T-! s!*( +ass +!%&*%"s "*s) *& )-! a)'a$ )%a(s$a)i*( +%!6i*'s$ !s%i#!.
I( ai)i*(8)* )%a(s$a)i(, )-! i(s)%')i*(s *& )-! s*'%! +%*,%a"8 )-! ass!"#$!% "'s) +%*!ss
s)a)!"!()s a$$! ass!"#$!% i%!)i6!s *% +s!'*i(s)%')i*(s.
T-!s! s)a)!"!()s a%! (*) )%a(s$a)! i()* "a-i(! i(s)%')i*(s.I(s)!a8)-! +%*6i!i(s)%')i*(s )* )-! ass!"#$!% i)s!$&.!1a"+$!BYTE8WOR7
I( *'% !1a"+$! +%*,%a"
STARTS+!i&i!s )-! s)a%)i(, "!"*% a%!ss &*% )-! *#!) +%*,%a". EN7S+!i&i !( *& )-! +%*,%a".
Fi(a$$8)-! ass!"#$!% "'s) 9%i)! ,!(!%a)! *#!) *! *()* s*"! *')+') !6i!.
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S.SELVARANI – AP/CSE
O#!) +%*,%a" &*%"a) is i6i! i()* t#ree t'%es o! recor(s)8 H!a!% T!1)
E(
T-! -!a!% %!*% *(s)ai(s )-! +%*,%a" (a"!8s)a%)i(, a%!ss a( $!(,)-. H!a!% %!*%
*$ H *$2 +%*,%a" (a"!
*$3 S)a%)i(, a%!ss *& *#!) +%*,%a"
*$4; L!(,)- *& *#!) +%*,%a" i( #)!s
T-! )!1) %!*%s *()ai( )-! )%a(s$a)! i(s)%')i*(s a( a)a *& )-! +%*,%a"8)*,!)-!% 9i)- a(i(ia)i*( *& )-! a%!ss!s 9-!%! )-!s! a%! )* #! $*a!.
T!1) R!*% *$ T
*$2 S)a%)i(, a%!ss &*% *#!) *! i( )-i %!*% *$; L!(,)- *& *#!) *! i( )-is %!*% i( #)!s
*$0<; O#!) *!8%!+%!s!()! i( -!1a!i"a$
). e!ine recor(.E$%lain. * 2 MARKS+
T-! !( %!*% "a%s )-! !( *& )-! *#!) +%*,%a" a( s+!i&i!s )-! a%!ss i( )-! +%*,%a"
9-!%! !1!')i*( is )* #!,i(.
E( %!*% *$ E
*$2 A%!ss *& &i%s) !1!')a#$! i(s)%')i*( i( *#!) +%*,%a".
T#e sco%e o! t#e assembler is, to -enerate obect co(e. But assembler (oes not /no0 t#e
a((ress e$actl'.so t#at t#e assembler c#oose %ass1 al-orit#m an( %ass 2 al-orit#m.
ass:1.Assi,( a%!ss!s )* a%! s)a)!"!()s i( )-! +%*,%a".
2.Sa6! )-! 6a$'!s assi,(! )* a%! $a#!$s &*% 's! i( +ass 2.
3.P!%&*%" s*"! +%*!ssi(, *& ass!"#$!% i%!)i6!s.
ass:2.Ass!"#$! i(s)%')i*(s.
2.G!(!%a)! a)a 6a$'!s. 3.P!%&*%" +%*!ssi(, *& ass!"#$!% i%!)i6!s (*) *(! '%i(, +ass .
4.W%i)! )-! *#!) +%*,%a" a( )-! ass!"#$ $is)i(,.
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CS 2304 SYSTEM SOFTWARE G.PRABHAKARAN – AP/CSE
S.SELVARANI – AP/CSE
). Assembler Al-orit#m an( atastructures:
O'% si"+$! ass!"#$!% 's!s t0o maor internal (ata stuctures3 T-! *+!%a)i*( *! )a#!$*4TAB+ T-! s"#*$ )a#$!*S5MTAB+
OPTAB is 's! )* $** '+ "(!"*(i *+!%a)i*( *!s a( )%a(s$a)! )-!" )* )-!i% "a-i(!
$a(,'a,! !5'i6a$!()s6.
SYMTAB is 's! )* s)*%! 6a$'!s assi,(! )* $a#!$s7.
LOCCTRT-is is a 6a%ia#$! )-a) is 's! )* -!$+ i( )-! assi,("!() *& a%!ss!s8.
LOCCTR is i()ia$i=! )* )-! #!,i((i(, a%!ss s+!i&i! i( )-! START s)a)!"!().
A&)!% !a- s*'%! s)a)!"!() is +%*!ss!8 )-! $!(,)- *& )-! ass!"#$! i(s)%')i*( *% a)a a%!a
)* #! ,!(!%a)! is a! )* LOCCTR.
W-!(!6!% 9! %!a- a $a#!$ i( )-! s*'%! +%*,%a"8)-! '%%!() 6a$'!s *& LOCCTR ,i6!s )-!a%!sss )* #! ass*ia)! 9i)- )-a) $a#!$.
2 MARKS
. "#' 'ou -o !or %ass 1 9 %ass 2 al-orit#m. State t#e reason.3. "#at are t#e (ata structures ise( in assembler6. e!ine o%tab.7. e!ine s'mtab.8. e!ine L4&&TR.
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CS 2304 SYSTEM SOFTWARE G.PRABHAKARAN – AP/CSE
S.SELVARANI – AP/CSE
).1 ASS 1 ASSEMBLER AL;4RIT<M= :
=. E$%lain in (etail about %ass1 assembler al-orit#m. *8 Mar/s+
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CS 2304 SYSTEM SOFTWARE G.PRABHAKARAN – AP/CSE
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).2 ASS 2 ASSEMBLER AL;4RIT<M1>
0. E$%lain in (etail about %ass2 assembler al-orit#m.*8 MARKS+
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CS 2304 SYSTEM SOFTWARE G.PRABHAKARAN – AP/CSE
S.SELVARANI – AP/CSE
R4EURE:
T<ERE ARE T<REE 4RATI4NS T4 FIN 4BCE&T &4E.
4ERATI4N 1: FIN MA&<INE LAN;UA;E EDUIALENT AN SUM "IT<FIRST T"4 BITS 4F RE;ISTER.
STE 1: FIN MA&<INE LAN;UA;E EDUIALENTSTE 2: FIN FIRST T"4 BITS 4F & 4R BASE RE;ISTER.STE ): &AL&ULATE E&IMAL ALUE 4F T"4 BITS.
E.;: STA 1 FIRST T"4 BITS 4F R4;RAM &4UNTER * 11 >>1>+ IS 11. T<E E&IMAL EDUIALANT IS 1 1
1 2>G 1
1 21G 2
)
AS ER 4UR R4&EURE, MA&<INE LAN;UA;E SUM "IT<RE;ISTER E&IMAL EDUIALANT. 1H) G 17.
4ERATI4N 2: FIN LAST T"4 BITS 4F RE;ISTER. AN &AL&ULATEE&IMAL EDUIALENT.
E.;: T<E LAST F4UR I;ITS 4F RE;ISTER IS >>1>. T<EE&IMAL EDUIALANT IS 2.
4ERATI4N ): FIN ISLA&EMENT ALUESTE 1: FIN T<E 4ERAN ARESS.STE 2: FIN T<E NET INSTRU&TI4N ARESS 4F T<E &URRENT
LINE.STE): &4NERT T<E STE 1 <EAE&IMAL ALUE INT4 E&IMAL.STE : &4NERT T<E STE 2 <EAE&IMAL ALUE INT4 E&IMAL.STE 3: SUBTRA&T STE ANS"ER FR4M STE 1.
STE6: &4NERT STE 3 ANS"ER INT4 <EAE&IMAL.STE7: SU4SE STE 3 ANS"ER IS NE;ATIE ALUE MEANS, FIN2S &4MLEMENT ALUE
E.;: 4EARN IS RETAR. T<E ARESS IS )>. NET INS ARESS IS ). ) > )
> 16>G> ) 16>G )
) 161G8
8
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CS 2304 SYSTEM SOFTWARE G.PRABHAKARAN – AP/CSE
S.SELVARANI – AP/CSE
8 ? ) G 3.
16 3 2
<EAE&IMAL >F 3 IS 2 .
E$am%le 1:
@ 000< CLOOP >S:B R7REC 4B003<.
.
.
40 00 > CLOOP 4@ 004 EN7FIL L7A EOF 03207
P%*,%a" *'()!% %!$a)i6! a%!ssi(, is8
0 0 0 ( i 1 # + !
Is) )9* #i)s a%! As ( a( i
H!1a!i"a$ !5'i6a$!() *& is 3.
&i( )-! is+$a!"!() 6a$'!s8
CLOOP $*a)i*( is 000< a( + 6a$'!s is A.
7!i"a$ !5'i6a$!() *& < is <8!i"a$ !5'i6a$a() i& A is 2<. <2< 20.
H!1a!i"a$ !5'i6a$!() *& 20 is 4.
T-! -!1a!i"a$ 6a$'!s 4 is 9%i))!( as #i(a% 6a$'!s.B!a's!8)-!
-!1a!i"a$ 6a$'! is -a6! 6! si,(!.As +!% *'%*(!+)8a$'$a)! 2s *"+$!"!() &*% )-a) 6a$'!.
4 is 9%i))!( as8 0000 000 000 4 #as! *( is+$a!"!(). A%!ss &*!$ is 2 #i)s
0 4
T-! 2s *"+$!"!() is8 T-! 2s *"+$!"!() +%*!'%! is8
Ta! s *"+$!"!() )-!( a )* )-! a(s9!% *& s *"+$!"!().
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0000 000 000 0 0 s *"+$!"!()
0 00 2s *"+$!"!()
F8 E08C 00
T#e obect co(e is )F2FE&.
i!!erence bet0een %c relati@e an( base relati@e a((ressin-11
. W-!( + %!$a)i6! a%!ssi(, is 's! )-! ass!"#$!% 9i$$ (*9 )-! *()!() *& +8*($ '%i(,
!1!')i*( )i"!.
2. B') i( #as! %!$a)i6! a%!ssi(, 8)-! +%*,%a""!% "'s) )!$$ )-! ass!"#$!% 9-a) )-! #as!%!,is)!% 9i$$ *()ai( '%i(, )-! !1!')i*( *& )-! +%*,%a" a( )-! ass!"#$!% 9i$$ a$'$a)! )-!
is+$a!"!().
.) ro-ram R elocation:
M*%! )-a( *(! +%*,%a" a( s-a%! )-! "!"*% a( *)-!% %!s*'%!s *& )-! "a-i(!.
I& 9! (!9 i( a6a(!89-i- +%*,%a" 9*'$ !1!')! *('%%!()$89! *'$ assi,(a%!ss89-!( )-! +%*,%a" 9!%! ass!"#$! s* )-a) )-! 9*'$ &i) )*,!)-!% 9i)-*')
*6!%$a+.B') +%a)ia$$ )-is "a (*) #! +*ssi#$!.
S* i) is !si%a#$! )* $*a a +%*,%a" i()* )-! "!"*% 9-!(!6!% )-!%! is a s+a! &*% i).
I( s'- as!s a)'a$ s)a%)i(, a%!ss *& )-! +%*,%a" is (*) (*9 '()i$ $*a )i"!.
I& )-! +%*,%a" is $*a! #!,i((i(, a) )-! $*a)i*( 0008)-! 6a%ia#$! THREE 6a$'! 9i$$
$*a)! a) a%!ss 027. I& )-! +%*,%a" is $*a! s)a%)i(, a) s*"! *)-!% a%!sss 20008)-! a%!ss 027 9i$$ (*)
*()ai( )-! a)'a$ 6a$'! *& THREE.
S* 9! -a6! )* "a! s*"! -a(,!s i( )-! a%!ss +*%)i*( *& )-! i(s)%')i*( i( *%!% )*
%!)%i!6! )-! *%%!) 6a$'!.
E,
000< CLOOP >S:B R7REC 4B003<.
.03< R7REC CLEAR ? B40
11. i!!erence bet0een %ro-ram counter a((ressin- an( base relati@e a((ressin-. *2 mar/s+
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CS 2304 SYSTEM SOFTWARE G.PRABHAKARAN – AP/CSE
S.SELVARANI – AP/CSE
&ase 1: T-! s)a)!"!() R7REC is +%!s!() a) )-! "!"*% $*a)i*( 03<8i& )-! +%*,%a" $*a! #!,i((i(,a) a%!ss 0000.
0000
.
000< 4B003< >S:B R7REC .
.03< B40 R7REC
&ase 2:@000
.
.@00< 4B0<03< >S:B R7REC
. .
<03< B40 R7RECT-! a%!ss *& )-! i(s)%')i*( >S:B )-! a%!ss *& $a#!$ R7REC.
T-! ass!"#$!% *!s (*) (*9 )-! a)'a$ $*a)i*( 9-!%! )-! +%*,%a" 9i$$ #! $*a!.H*9!6!% )-!
ass!"#$!% a( i!()i& &*% )-! $*a!% )-*s! +a%)s *& )-! *#!) +%*,%a" )-a) (!! "*i&ia)i*(.A( *#!) +%*,%a" )-a) *()ai( )-! i(&*%"a)i*( )* +!%&*%" )-is i( *& "*i&ia)i*( is a$$! a
%!$*a)a#$! +%*,%a".
Relocation ro-ram Sol@in- Ste%s:
W-!( )-! ass!"#$!% ,!(!%a)!s )-! *#!) *! &*% )-! >S:B i(s)%')i*(8i) 9i$$ i(s!%) )-!
a%!ss *& R7REC8%!$a)i6! )* )-! s)a%) *& )-! +%*,%a".T-is is )-! %!as*( 9! i()ia$i=! )-!$*a)i*( *'()!% )* 0 &*% )-! ass!"#$
T-! ass!"#$!% 9i$$ a$s* +%*'! a *""a( &*% )-! $*a!%8i(s)%')i(, i) )* a )-!#!,i((i(, a%!ss *& )-! +%*,%a" )* )-! a%!ss &i!$ i( )-! >S:B i(s)%')i*( a) $*a )i"!.
Mo(i!ication Recor(12 :
*$ M
*$2 S)a%)i(, $*a)i*( *& )-! a%!ss &i!$ )* #! "*i&i! %!$a)i6! )* )-! #!,i((i(, *&)-! +%*,%a".
C*$; L!(,)- *& a%!ss &i!$ )* #! "*i&i! i( -a$& #)!s.
i!. 4 #i)s -a$& #)!
F*% a$$ )-! i(s)%')i*( 9-i- 's!s !1)!(! &*%"a) i(s)%')i*(8%!$*a)i*( "'s) #! +!%&*%"!8s* "*i&ia)i*( %!*% "'s) #! a!.
O)-!% $i(!s i( )-! +%*,%a" * (*) %!5'i%! "*i&ia)i*( as )-! 's! + %!$a)i6! *% #as!
%!$a)i6! a%!ssi(,.
2. 7!&i(! M*i&ia)i*( %!*%.E1+$ai(.2 "a%s.
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CS 2304 SYSTEM SOFTWARE G.PRABHAKARAN – AP/CSE
S.SELVARANI – AP/CSE
3. Mac#ine In(e%en(ent Assembler Features:
T-is &!a)'%!s )-a) a%! *""*($ &*'( i( i"+$!"!()a)i*( *& )-is )+! *& s*&)9a%! a( )-a) a%!
%!$a)i6!$ "a-i(! i(!+!(!().
3.1 Literals1) :
P%*,%a""!% is *(6!(i!() )* 9%i)! )-! 6a$'! *& a *(s)a() *+!%a( as a +a%) *& )-!
i(s)%')i*( )-a) 's!s i).
T-is a6*is -a6i(, !&i(! )-! *(s)a()ss 9-!%! i( )-! +%*,%a" a( "a! '+ a $a#!$ &*% i).
S'- a( *+!%a( is a$$! as $i)!%a$Q8#!a's! )-! 6a$'! is s)a)! $i)!%a$$Q i( )-! i(s)%')i*(.
Li)!%a$ is i!()i&i! 9i)- )-! +%!&i1 89-i- is &*$$*9! # a s+!i&ia)i*( *& )-! $i)!%a$
6a$'!. E,
4@ 00A EN7FIL L7A CEOF032002@ 0<2 WLOOP T7 ?0@E320
i!!erence bet0een Literal an( Imme(iate 4%eran(1
A( i""!ia)! a%!ssi(, 8)-! *+!%a( 6a$'! i*s ass!"#$! as +a%) *& )-! "a-i(!
i(s)%')i*(.I( $i)!%a$ )-! ass!"#$!% "'s) ,!(!%a)! )-! 6a$'! as a *(s)a() i( a( *& )-!"!"*% $*a)i*(.
A%!ss *& )-! *(s)a() is assi,(! as )-! )a%,!) a%!ss.
3.1.1 Literal ool13 :
Li)!%a$s a%! s)*%! i( $i)!%a$ +**$.T-is *+!%a)i*( is a%%i! *') )-! !( *& )-! +%*,%a".
LT4R;Ass!"#$!% i%!)i6!s
I) %!a)!s )-! $i)!%a$s +**$ i""!ia)!$ a( s)*%! )-! $i)!%a$s '()i$ )-! +%!6i*'s LTORG.
O(! a $i)!%a$ is s)*%! i( )-! $i)!%a$ +**$ )-!( i) is ((*) %!+!a)! a,ai(.
I( s*"! +%*,%a" )-! LTORG is +$a! i( )-! "i$! *& )-! +%*,%a"8 )-is is #!a's! )-!$i)!%a$s a%! +$a! i( )-! +**$ a) )-! !( *& )-! +%*,%a".
W-!( )-!%! is a $i)!%a$ a) )-! #!,i((i(, *& )-! +%*,%a" a( )-! +%*,%a" -as 300 $i(!s "!a(s
)-!( )-! s)a%)i(, a%!ss *& )-! $i)!%a$ +**$ is a) )-! !( *& )-! +%*,%a".
T-! %!&!%!(! &*% )-! *+!%a( "a! )-! + )* ,* &*% )* %!a- $i)!%a$ a( )-is 9as)! )-!)i"!.S* i) is +*ssi#$! )* 's! as "'- LTORG s)a)!"!() i( )-! +%*,%a".
M*s) *& )-! ass!"#$!% *!s (*) a$$*9 '+$ia)i*( *& $i)!%a$s i( )-! $i)!%a$ +**$.T-! a$$*9 )-!
sa"! $i)!%a$ 's! "*%! )-a( *(! +$a! i( )-! +%*,%a". I( $i)!%a$ +**$ *($ *(! *+ *& )-! s+!i&i! a)! 6a$'! is s)*%!.
B!&*%! a$$*a)i(, s+a! &*% a $i)!%a$ i( )-! +**$8i) is 6!%i&i! )-a) is )-!%! )-! sa"! $i)!%a$ is
a$%!a i( )-! +**$ # "!a(s *& *"+a%i(, )-! $i)!%a$s i( )-! +**$ -a%a)!% 9i)- )-! (!9
$i)!%a$.
3. 7!&i(! $i)!%a$s.2 "a%s
4. 7i&!%()ia)! $i)!%a$ a( i""!ia)! *+!%a(.2 "a%s
@. 7!&i(! $i)!%a$ +**$. 2"a%s
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CS 2304 SYSTEM SOFTWARE G.PRABHAKARAN – AP/CSE
S.SELVARANI – AP/CSE
F*% !1a"+$!8
Sa"! $i)!%a$ is 's! "*%! )-a( *(!8a( )-! $i)!%a$ -as i&&!%!() 6a$'!s '%i(, )-! !1!')i*( *&)-! +%*,%a".H!%! a*%i(, )* )-! '+$ia)i*( *& $i)!%a$s i( )-! +**$8)-! a#*6! "!()i*(! $i)!%a$ is
a++!a%! *(! i( )-! +**$ a( )-! !1!')i*( "a #! a +%*#$!".
T-! s*$')i*( is %!a)! #asi a)a s)%')'%! $i)!%a$ )a#!$LITTAB16
Li)!%a$ )a#!$ *()ai(s8
Li)!%a$ (a"! T-! *+!%a( 6a$'! a( $!(,)-
A%!ss assi,(! )* )-! *+!%a(
7'%i(, +ass )-! ass!"#$!% s!a%-!s )-! LITTAB &*% a $i)!%a$ (a"!.I& )-! $i)!%a$ is +%!s!()
"!a(s (* +%*#$!".I& i) is (*) )-! $i)!%a$ is a! )* )-! $i)!%a$ )a#!$.
7'%i(, +ass 2 )-! ass!"#$!% s!a%-!s )-! LITTAB &*% )-! $i)!%a$ a%!ss &*% *#!) *!
,!(!%a)i*(.
3.2 S'mbol(e!inin- Statements17 :
:s!% !&i(! s"#*$s i( ass!"#$!% $a(,'a,! +%*,%a" -a6! a++!a%! as $a#!$s *( i(s)%')i*(
*% a)a a%!as.
T-! 6a$'! *& s'- a $a#!$ is )-! a%!ss assi,(! )* )-! s)a)!"!() *( 9-i- i) a++!a%s.
M*s) ass!"#$!% +%*6i!s a( ass!"#$!% i%!)i6! )-a) a$$*9s )-! +%*,%a""!% )* !&i(!s"#*$s a( a+!i& )-!i% 6a$'!s.
T-! ass!"#$!% i%!)i6! ,!(!%a$$ 's! i( EDU.
T-! ,!(!%a$ &*%" *& s'- s)a)!"!() is8s"#*$ ED: 6a$'!.
T-is s)a)!"!() !&i(!s )-! ,i6!( s"#*$ a( assi,(s )-! 6a$'! s+!i&i! )* i).
T-! 6a$'! "a #! ,i6!( as8 A *(s)a().
As a( !1+%!ssi*( i(6*$6i(, *()!()s. P%!6i*'s$ !&i(! s"#*$s.
O(! 's! *& ED: is )* !s)a#$is- s"#*$i (a"!s )-a) a( #! 's! &*% i"+%*6! %!aa#i$i) i(
+$a! *& ('"!%i 6a$'!s.E,
L7T 40;<
)* $*a )-! 6a$'!s 40;< i()* %!,is)!% T.T-is 6a$'!s %!+%!s!()s )-! "a1i"'" $!(,)- %!*%.W! *'$%!a 9i)- s'#%*')i(! R7REC.
MA?LEN ED: 40;<A( )-! a$$i(, s)a)!"!() $i! )-is
L7T MA?LENN*9 i) is $!a% )-a) MA? LEN is %!+$a! 9i)- )-! 6a$'!s 40;< '%i(, !1!')i*(.Ass!"#$!%
!(*'()!%s )-! ED: a( s)*%!s i) i( )-! SYMTAB 9i)- i)s 6a$'! 40;<.
A(*)-!% *""*( 's! *& ED: is i( !&i(i(, "(!"*(is (a"!s &*% %!,is)!%s.
<. 7!&i(! LITTAB.2 "a%s. 7!&i(! s"#*$ !&i(i(, s)a)!"!()s.2"a%s
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CS 2304 SYSTEM SOFTWARE G.PRABHAKARAN – AP/CSE
S.SELVARANI – AP/CSE
E,A ED: 0 BASE ED: R
? ED: CO:NT ED: R2L ED: 2 IN7E? ED: R3
T-!s! s)a)!"!()s s+!i& a #)! $i)!%a$ 9i)- )-! -!1a!i"a$ 6a$'! [email protected]! (*)a)i*( 's!
&*% $i)!%a$ 6a%i!s &%*" ass!"#$!% )* ass!"#$!%.
I) is i"+*%)a() )* '(!%s)a( )-! i&&!%!(! #!)9!!( a $i)!%a$ a( a( i""!ia)! *+!%a( 9i)-
i""!ia)! a%!ssi(,8)-! *+!%a( 6a$'! is ass!"#$! as +a%) *& )-! "a-i(! i(s)%')i*(.
Wi)- $i)!%a$ )-! ass!"#$!% ,!(!%a)!s )-! s+!i&i! 6a$'! as a *(s)a() a) s*"! *)-!% "!"*%$*a)i*(.
BASE J
L7B J
A(*)-!% assembler (irecti@e is calle( 4R;.T-is is use( to in(irectl' assi-n t#e @alues )*
s'mbols.
W-!( 6a$'! is a *(s)a() *% a( !1+%!ssi*( i(6*$6i(, *(s)a()s a( +%!6i*'s$ !&i(!s"#*$.
SYMBOL RESB <
VAL:E RESB FLAGS RESB 2
ORG STAB 00
T-! &i%s) ORG %!s!)s )-! $*a)i*( *'()!% )* )-! 6a$'! *& STAB.T-! $a#!$ *( )-! &*$$*9i(,RESB s)a)!"!()s !&i(!s SYMBOL )* -a6! )-! '%%!() 6a$'! i( LOCCTR.
i!)-! sa"! a%!ss assi,(! )* SYMTAB LOCCTR.
3.) E$%ressions:
O'% +%!6i*'s !1a"+$!s *& ass!"#$!% $a(,'a,! s)a)!"!()s -a6! 's! si(,$! )!%"s $i!
$a#!$8$i)!%a$8!).8as i(s)%')i*( *+!%a(s.
M*s) *& )-! ass!"#$!%s 's! !1+%!ssi*( 9-!%!6!% a si(,$! *+!%a( is +!%"i))!.
S'- !1+%!ssi*( is !6a$'a)! # )-! ass!"#$!% a( )-! %!s'$) is 's! as )-! (*%"a$ *+!%a(.
A%i)-"!)i !1+%!ssi*(s a%! a$$*9! a( i) "'s) &*$$*9 )-! (*%"a$ %'$!s 'si(, )-! *+!%a)*%s
88J a( /.
T-is s)a)!"!() is !(*'()!%! '%i(, ass!"#$ *& a +%*,%a"8)-! ass!"#$!% %!&!%s i)s $*a)i*(
*()ai(LOCCTR)* )-! s+!i&i! 6a$'! 9! a( !&i(! a s"#*$ )a#!$ 9i)- a$$ &*$$*9i(,s)%')'%!s.
SYMBOL VAL:E FLAGS
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I( )-is )a#!$8SYMBOL &i!$ *()ai(< #)! 's!%!&i(! s"#*$sVAL:E is a *(!9*%
%!+%!s!()a)i*( *& )-! 6a$'! assi,(! )* )-! s"#*$FLAGS is a 2#)! &i!$ )-a) s+!i&i!s
s"#*$ )+! a( *)-!% i(&*%"a)i*(.
STAB RESB 00 Wi)- ED: s)a)!"!()s8
SYMBOL ED: STAB
VAL:E ED: STAB<
FLAGS ED: STAB;
Wi)- -!$+ *& ass!"#$!% i%!)i6! ORG89! a( 9%i)! )-*s! s)a)!"()s8STAB RESB 00
ORG STAB
7i6isi*( is 's'a$$ !&i(! )* +%*'! a( i()!,!% %!s'$).I(i6i'a$ )!%"s i( )-! !1+%!ssi*(
"a #! *(s)a()8's!%!&i(! s"#*$s*%s+!ia$ )!%"s8*""*( s+!ia$ )!%" is )-! '%%!()
6a$'! *& )-! $*a)i*( *'()!%!si,(a)! # J.i!)-! 6a$'! *& )-! (!1) '(assi,(! "!"*%$*a)i*(.
B:FEN7 ED: J
T-! a#*6! !1+%!ssi*( ,i6!s B:FEN7 a 6a$'! )-a) is )-! a%!ss *& )-! (!1) #)! a&)!% )-!#'&&!% a%!a.
S*"! 6a$'!s i( )-! *#!) +%*,%a" a%! %!$a)i6! )* )-! #!,i((i(, *& )-! +%*,%a"89-i$! *)-!%s
a%! a#s*$')!.
Si"i$a%$8)-! 6a$'!s *& )!%"s a( !1+%!ssi*(s a%! !i)-!% %!$a)i6! *% a#s*$')!.
A *(s)a() is a( a#s*$')! )!%".La#!$s *( i(s)%')i*(s a( a)a a%!as8a( %!&!%!(!s )* )-!
$*a)i*( *'()!% 6a$'!8a%! %!$a)i6! )!%"s.
A s"#*$ 9-*s! 6a$'! is ,i6!( # ED: "a #! !i)-!% a( a#s*$')! )!%" *% a %!$a)i6! )!%"
!+!(i(, '+*( )-! !1+%!ssi*( 's! )* !&i(! i)s 6a$'!. E$%ressions are classi!ie( as18,
JAbsolute e$%ression JRelati@e e$%ression
T-! !1+%!ssi*(s a%! !+!(i(, '+*( )-! )+! *& 6a$'! )-! +%*'!.
E1+%!ssi*( )-a) *()ai(s *($ a#s*$')! )!%"s a%! *"! '(!% a#s*$')! !1+%!ssi*(.
T-!%! a%! some con(itions1=
)* 's! )-! %!$a)i6! )!%"s i( )-! !1+%!ssi*(s8
JE@er' relati@e term is %aire( 0it# anot#er relati@e term. JRemainin- un%aire( term is assi-ne( 0it# a %asiti@e si-n.
JRelati@e term is not allo0e( !or multi%lication an( (i@ision o%eration. E1+%!ssi*(s )-a) * (*) *"! '(!% a#s*$')! *% %!$a)i6! a%! &$a,,! # )-! ass!"#$!% a(
!%%*%s.
S*"! )i"!% %!$a)i6! )!%"s a%! +ai%! 9i)- *++*si)! si,(s8i( )-a) as! )-! %!s'$) is a( a#s*$')!
6a$'!. MA?LEN ED: B:FEN7B:FFER
. 7!&i(! !1+%!ssi*(s. W-a)% a%! )+!s *& !1+%!ssi*(.2 "a%s.
;. W-a) a%! *(i)i*(s )* 's! )-! %!$a)i6! )!%"s i( !1+%!ssi*(s.2 "a%s
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CS 2304 SYSTEM SOFTWARE G.PRABHAKARAN – AP/CSE
S.SELVARANI – AP/CSE
B$* Na"! B$* N'"#!% A%!ss L!(,)-
7!&a'$) 0 0000 00<<
C 7ATA 00<< 0003
C BLKS 2 00 000
3..1 &ontrol Section an( ro-ram lin/in-:
A *()%*$ s!)i*( is a +a%) *& +%*,%a" )-a) "ai()ai(s i)s i!()i& a&)!% ass!"#$.
Ea- s'- *()%*$ s!)i*( a( #! $*a! a( %!$*a)! i(!+!(!()$ *& )-! *)-!%s.
7i&&&!%!() *()%*$ s!)i*(s a%! "*s) *&)!( 's! &*% s'#%*')i(!s *% *)-!% $*,ia$ s'#i6isi*(s
*& a +%*,%a". T-! +%*,%a""!% a( ass!"#$!8$*a a( "a(i+'$a)! !a- *& )-!s! *()%*$ s!)i*(s
s!+!%a)!$.T-! %!s'$)i(, &$!1i#i$i) is a "a*% #!(!&i) *& 'si(, *()%*$ s!)i*(s.
W-!( *()%*$ s!)i*( &*%" $*,ia$$ %!$a)! +a%)s *& a +%*,%a"8i) is (!!ssa% )* +%*6i!s*"! "!a(s &*% $i(i(, )-!" )*,!)-!%.
I(s)%')i*(s i( *(! *()%*$ s!)i*( "i,-) (!! )* %!&!% )* i(s)%')i*(s *% a)a $*a)! i(
a(*)-!% s!)i*(.
B!sa's! *()%*$ s!)i*(s a%! i(!+!(!()$ $*a! a( %!$*a)! 8)-! ass!"#$!% is '(a#$! )*+%*!ss )-!s! %!&!%!(!s i( )-! 's'a$ 9a.
T-! ass!"#$!% -as (* i!a 9-!%! a( *()%*$ s!)i*( 9i$$ #! $*a)! a) !1!')i*( )i"!.S'-
%!&!%!(!s #!)9!!( *()%*$ !1)!%(a$ %!&!%!(!s. I( )-is as! )-!%! a%! )-%!! *()%*$ s!)i*(s.O(! &*% )-! "ai( +%*,%a" a( &*% !a-
s'#%*')i(!. P%*,%a" #$*s )%a! )-%*',- )-! ass!"#$ a( $*ai(, +%*!ss.
C*()%*$ s!)i*(s i&&!% &%*" +%*,%a" #$*s i( )-a) )-! a%! -a($! s!+!%a)!$ # )-!ass!"#$!%.
S"#*$s )-a) a%! !&i(! i( *()%*$ s!)i*( "a (*) #! 's! i%!)$ # a(*)-!% s!)i*()-!
"'s) #! i!()i&i! as !1)!%(a$ %!&!%!(!s &*% $*a!% )* -a($!.
E?T7EF – E?TERNAL 7EFINITIONE?TREF – E?TERNAL REFERENCE
T-! )9* (!9 %!*% )+!s21 a%! EFINE a( REFER . A e!ine %!*% ,i6!s i(&*%"a)i*(
a#*') !1)!%(a$ s"#*$ )-a) a%! !&i(! i( )-is *()%*$ s!)i*(. A Re!er %!*% $is)s s"#*$s)-a) a%! i!$ as !1)!%(a$ %!&!%!(!s # )-! *()%*$ s!)i*(.
EFINE RE&4R:&4L 1 : &4L 27 :Name o! t#e e$ternal s'mbol (e!ine( in t#is &ontrol section.&4L 81) :Relati@e a((ress o! s'mbol.&4L 17) : Re%eat in!ormation in col 21) !or ot#er e$ternal s'mbol.
21. e!ine EFINE recor( an( REFER recor(.e$%lain.* 2 mar/s+
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CS 2304 SYSTEM SOFTWARE G.PRABHAKARAN – AP/CSE
S.SELVARANI – AP/CSE
REFER RE&4R:&4L 1 : R
&4L 27 :Name o! e$ternal s'mbol.&4L 81) :Name o! t#e ot#er e$ternal re!erence s'mbols.
M4IFI&ATI4N RE&4R:&4L 1 : M&4L 27 :Startin- a((ress o! t#e !iel( to be mo(i!ie(.&4L 8= :Len-t# o! t#e !iel( to be mo(i!ie( as #al! b'tes.&4L 1> :Mo(i!ication !la-.&4L 1116 :E$ternal s'mbol 0#ose @alue is to be a((e( or subtracte( to t#e
in(ication !iel(.
6. 4ne %ass assemblers an( Multi%ass assemblers:
6.1 4neass Assemblers:
S!(a%i* &*% *(!+ass ass!"#$!%s
G!(!%a)! )-!i% *#!) *! i( "!"*% &*% i""!ia)! !1!')i*( – $*aa(,*
ass!"#$!%.
E1)!%(a$ s)*%a,! &*% )-! i()!%"!ia)! &i$! #!)9!!( )9* +ass!s is s$*9 *% is
i(*(6!(i!() )* 's!.
Mai( +%*#$!" F*%9a% %!&!%!(!s
7a)a i)!"s
La#!$s *( i(s)%')i*(s
S*$')i*(
R!5'i%! )-a) a$$ a%!as #! !&i(! #!&*%! )-! a%! %!&!%!(!.
I) is +*ssi#$!8 a$)-*',- i(*(6!(i!()8 )* * s* &*% a)a i)!"s.
F*%9a% '"+ )* i(s)%')i*( i)!"s a((*) #! !asi$ !$i"i(a)!.
I(s!%) $a#!$8 a%!ssU)*U#!U"*i&i! )* SYMTAB
:s'a$$8 a%!ssU)*U#!U"*i&i! is s)*%! i( a $i(!$is)
6.1.1For0ar( Re!erence in 4ne%ass Assembler:
O"i)s )-! *+!%a( a%!ss i& )-! s"#*$ -as (*) !) #!!( !&i(!.
E()!%s )-is '(!&i(! s"#*$ i()* SYMTAB a( i(ia)!s )-a) i) is '(!&i(!
As )-! a%!ss *& )-is *+!%a( a%!ss )* a $is) *& &*%9a% %!&!%!(!s ass*ia)!
9i)- )-! SYMTAB !()%.
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CS 2304 SYSTEM SOFTWARE G.PRABHAKARAN – AP/CSE
S.SELVARANI – AP/CSE
W-!( )-! !&i(i)i*( &*% )-! s"#*$ is !(*'()!%!8 sa(s )-! %!&!%!(! $is) a(
i(s!%)s )-! a%!ss.
A) )-! !( *& )-! +%*,%a"8 %!+*%)s )-! !%%*% i& )-!%! a%! s)i$$ SYMTAB !()%i!s
i(ia)! '(!&i(! s"#*$s.
6.2 Multiass Assemblers:
F*% a )9* +ass ass!"#$!%8 &*%9a% %!&!%!(!s i( s"#*$ !&i(i)i*( a%! (*) a$$*9!
ALPHA ED: BETA
BETA ED: 7ELTA
7ELTA RESW
S"#*$ !&i(i)i*( "'s) #! *"+$!)! i( +ass .
P%*-i#i)i(, &*%9a% %!&!%!(!s i( s"#*$ !&i(i)i*( is (*) a s!%i*'s i(*(6!(i!(!.
F*%9a% %!&!%!(!s )!( )* %!a)! i&&i'$) &*% a +!%s*( %!ai(, )-! +%*,%a".
6.2.1 Im%lementation:
F*% a &*%9a% %!&!%!(! i( s"#*$ !&i(i)i*(8 9! s)*%! i( )-! SYMTAB
T-! s"#*$ (a"!
T-! !&i(i(, !1+%!ssi*(
T-! ('"#!% *& '(!&i(! s"#*$s i( )-! !&i(i(, !1+%!ssi*(
T-! '(!&i(! s"#*$ "a%! 9i)- a &$a, J ass*ia)! 9i)- a $is) *&
s"#*$s !+!( *( )-is '(!&i(! s"#*$.
W-!( a s"#*$ is !&i(!8 9! a( %!'%si6!$ !6a$'a)! )-! s"#*$
!1+%!ssi*(s !+!(i(, *( )-! (!9$ !&i(! s"#*$.
MLEMENTATI4N EAMLE:
MASAM ass!"#$!%
SPARC ass!"#$!%
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CS 2304 SYSTEM SOFTWARE G.PRABHAKARAN – AP/CSE
S.SELVARANI – AP/CSE
MASAM assembler
MASAM ass!"#$!% is 9%i))!( &*% P!()i'" a( *)-!% 1 < ss)!"s.
Si(! 1 < ss)!" 6i!9s "!"*% as a *$$!)i*( *& s!,"!()s8 MASAM
ass!"#$!% $a(,'a,! +%*,%a" is 9%i))!( as a *$$!)i*( *& s!,"!()s.
Ea- s!,"!() is !&i(! as #!$*(,i(, )* a +a%)i'$a% $ass.
C*""*($ 's! $ass!s a%! CO7E8 7ATA8 CONST a( STACK.
7'%i(, +%*,%a" !1!')i*(8 s!,"!()s a%! a%!ss! 6ia )-! 1 < s!,"!()
%!,is)!%s.
C*! s!,"!() a%! a%!ss! 'si(, %!,is)!% CS
S)a%) s!,"!()s a%! a%!ss! 'si(, %!,is)!% SS
7a)a s!,"!()s a%! a%!ss! 'si(, 7S *% GS.
>'"+ i(s)%')i*(s a%! ass!"#$! i( )9* i&&!%!() 9as
N!a% '"+
Fa% '"+
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