42 lines
901 B
Text
42 lines
901 B
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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p : process user(wp,wq);
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q : process user(wq,wp);
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ASSIGN
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init(wp) := FALSE;
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init(wq) := FALSE;
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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 = enter -> AF (p.state = critical | q.state = critical))
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SPEC -- INDIVIDUAL STARVATION
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AG (p.state = enter -> AF p.state = critical)
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MODULE user(wp, wq)
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VAR
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state : {local,enter,set,critical,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, enter};
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state = enter & wq = FALSE : set;
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state = set : critical;
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state = critical : 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 = exit : FALSE;
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TRUE : wp;
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esac;
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FAIRNESS
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running
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