$A NLS=1
$A TAB=0,3,6,9,12,15,18,21,24,27,30
$B0
%SEMAPHORE MANAGERSEM
$B0
%CYCLING %SEMAPHORE MUTEX1, MUTEX3,R,W
$B2
%BEGIN %PROCESS
$B0
%CAPABILITY .PROCESS
$B0
%CYCLING %SEMAPHORE THE STATUS
$B0
%CYCLE
$B0
$A INDENT=2
READER ENTRY
$B0
%CYCLE
$A INDENT=3
.PROCESS = NEXT PROCESS( .PROCESS .LIST)
$B0
%IF .PROCESS # .NULL %THEN %START
$A INDENT=4
_@P (THE STATUS)
$A INDENT=5
%IF .PROCESS$_STATUS = 'READY' %THEN %START
$A INDENT=6
.PROCESS$_STATUS = 'RUNNING'
$A INDENT=5
%FINISH %ELSE %START
$A INDENT=6
.PROCESS = .DUMMY
$A INDENT=5
%FINISH
$A INDENT=4
_@V(THE STATUS)
$A INDENT=3
%FINISH
$A INDENT=2
%REPEAT %UNTIL .PROCESS # .DUMMY
$B0
READER EXIT
$B0
%IF %PROCESS # .NULL %THEN %START
$A INDENT=3
RESUME-PROCESS( .PROCESS)
$A INDENT=2
%FINISH %ELSE %START
$B0
$T3
@V(MANAGERSEM)
$B0
%FINISH
$A INDENT=2
%REPEAT
$B
%END %PROCESS
$B2
$L1 M
@FIGURE 4.2-5A


$B5
$L8
%BEGIN %PROCESS
  %CYCLE
      DETERMINE APPROPIATE MODIFICATIONS ON PROCESS LIST
     WRITER ENTRY
        UPDATE ( .PROCESS .LIST )
     WRITER EXIT
   %REPEAT
%END %PROCESS
$B
$L1 M
@FIGURE 4.2-5B
$E
$A INDENT=2; NLS=1
$C-7 @P(S) =  $C+3 [ S = S-1 ; %IF S < 0 %THEN -> L1 ]
$B
$C-4 CRITICAL SECTION:
$B
$C+5 $.
$B0
$C+5 $.
$B0
$C+5 $.
$B
L1: [ %IF .CYS < 1 %THEN -> L1 ; .CYS = .CYS-1 ]
$B
$A INDENT=3; NLS=2
QUEUE UP(QS,ME)
$B0
[ .NUMQPR = .NUMQPR+1 ]
$B0
.ACTIVATOR = BLOCK-PROCESS(ME)
$B0
RESUME-PROCESS .(ACTIVATOR)
$B0
[ .CYS = .CYS+1 ]
$B0
-> CRITICAL SECTION
$A INDENT=0
AND
$A INDENT=2; NLS=1
$C-7 @V(S) = $C+3   [ S = S+1 ; %IF S <= 0 %THEN -> L2 ]
$B
$C+5 $.
$B0
$C+5 $.
$B0
$C+5 $.
$A INDENT=3; NLS=2
$B
$C-4 L2: [%IF .NUMQPR<1 %THEN -> L2 ; .NUMQPR$=NUMQPR+1]
$B0
$C-4 L3: [ %IF .CYS < 1 %THEN -> L3 ; .CYS = .CYS-1 ]
$B0
ID = DEQUEUE(QS)
$B0
WAKE-UP-PROCESS(ID)
$B0
[ .CYS = .CYS+1 ]
$B0
-> INSTRUCTION FOLLOWING THE @V
$A INDENT=0
$B2
$L1 M
FIGURE 4.2-3.
$E
$A TAB=1,3,5,7,9,34,36,38
$T1 %ROUTINE READER ENTRY
$T6 %ROUTINE WRITER ENTRY
$B0
$T2 _@P(MUTEX3) $T7 @P(MUTEX2)
$B0
$T3 _@P(R) $T8 WRITECOUNT=WRITECOUNT+1
$B0
$T4 _@P(MUTEX1) $T8 %IF WRITECOUNT=1 %THEN _@P(R)
$B0
$T5 READCOUNT=READCOUNT+1 $T7 @V(MUTEX2)
$B0
$T5  %IF READCOUNT=1 %THEN _@P(W)
$T7 _@P(W)
$B0
$T4 _@V(MUTEX1) $T6 %END
$B0
$T3 _@V(R)
$B0
$T2 _@P(MUTEX3)
$B0
%END
$B4
%ROUTINE READER EXIT  $T6 %ROUTINE WRITER EXIT
$B0
$T2 _@P(MUTEX1) $T7 _@V(W)
$B0
$T3 READCOUNT=READCOUNT-1 $T7 @P(MUTEX2)
$B0
$T3 %IF READCOUNT=0 %THEN _@V(W) $T8 WRITECOUNT=WRITECOUNT-1
$B0
$T2 _@V(MUTEX1) $T8 %IF WRITECOUNT=0 %THEN _@V(R)
$B0
%END $T7 @V(MUTEX2)
$B0
$T6 %END
$B3
$L1 M
@FIGURE 4.2-6.
$E
$A NLS=1
$A TAB=0,3,6,9,12,15,18,21,24,27,30
$B0
%SEMAPHORE MANAGERSEM
$B0
%CYCLING %SEMAPHORE MUTEX1, MUTEX3,R,W
$B2
%BEGIN %PROCESS
$B0
%CAPABILITY .PROCESS
$B0
$B0
%CYCLE
$B0
$A INDENT=2
READER ENTRY
$B0
%CYCLE
$A INDENT=3
.PROCESS = NEXT PROCESS( .PROCESS .LIST)
$B0
%IF .PROCESS # .NULL %THEN %START
$A INDENT=4
$B
%IF .PROCESS$_STATUS = 1 %THEN %START
$A INDENT=3
TRY AGAIN:
$A INDENT=5
.ITS .PROCESS$_STATUS,DOIRE
$B0
%EXIT $T10 ;! EXIT THE %CYCLE
$A INDENT=3
DOIRE:
$A INDENT=5
.IRE .PROCESS$_STATUS,REPEAT
$B0
-> TRY AGAIN
$A INDENT=3
REPEAT:
$A INDENT=5
.PROCESS = .DUMMY
$A INDENT=4
%FINISH
$A INDENT=3
$B
%FINISH
$A INDENT=2
%REPEAT %UNTIL .PROCESS # .DUMMY
$B0
READER EXIT
$B0
%IF %PROCESS # .NULL %THEN %START
$A INDENT=3
RESUME-PROCESS( .PROCESS)
$A INDENT=2
%FINISH %ELSE %START
$B0
$T3
@V(MANAGERSEM)
$B0
%FINISH
$A INDENT=2
%REPEAT
$B
%END %PROCESS


$B5
$L8
%BEGIN %PROCESS
  %CYCLE
      DETERMINE APPROPIATE MODIFICATIONS ON PROCESS LIST
     WRITER ENTRY
        UPDATE ( .PROCESS .LIST )
     WRITER EXIT
   %REPEAT
%END %PROCESS
$B
$L1 M
@FIGURE @A1
$E