62 lines
1.6 KiB
Text
62 lines
1.6 KiB
Text
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MODULE main
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VAR
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wp : boolean;
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wq : boolean;
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turn : 1..2;
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p : process user(wp,wq, turn, 1, 2);
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q : process user(wq,wp, turn, 2, 1);
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ASSIGN
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init(wp) := FALSE;
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init(wq) := FALSE;
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init(turn) := 1;
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SPEC -- PROGRESS
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AG (p.state = local -> EF p.state = enter )
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SPEC -- MUTUAL EXCLUSION
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AG !(p.state = critical & q.state = critical)
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SPEC -- DEADLOCK
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AG (p.state = set -> AF (p.state = critical | q.state = critical))
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SPEC -- INDIVIDUAL STARVATION
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AG (p.state = set -> AF p.state = critical)
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MODULE user(wp, wq, turn, me, other)
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VAR
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state : {local, set, enter, checkTurn, loopUnset, waitTurn, loopSet, critical, setTurn, exit};
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ASSIGN
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init(state) := local;
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next(state) :=
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case
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state = local : {local, set};
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state = set : enter;
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state = enter & wq = FALSE : critical; -- Go to CS
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state = enter & wq = TRUE : checkTurn; -- Start waiting loop
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state = checkTurn & turn = me : enter; -- Go back to loop check
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state = checkTurn & turn = other : loopUnset; -- Descend in loop
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state = loopUnset : waitTurn;
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state = waitTurn & turn = me : loopSet; -- Wait until turn == 1
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state = loopSet : enter; -- End of loop
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state = critical : exit;
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state = setTurn : exit;
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state = exit : local;
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TRUE : state;
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esac;
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next(wp) :=
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case
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state = set : TRUE;
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state = loopUnset : FALSE;
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state = loopSet : TRUE;
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state = exit : FALSE;
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TRUE : wp;
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esac;
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next(turn) :=
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case
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state = setTurn : other;
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TRUE : turn;
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esac;
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FAIRNESS
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running
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