62 lines
1.6 KiB
Prolog
62 lines
1.6 KiB
Prolog
/*************************************************************************
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* *
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* YAP Prolog *
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* *
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* Yap Prolog was developed at NCCUP - Universidade do Porto *
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* *
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* Copyright L.Damas, V.S.Costa and Universidade do Porto 1985-1997 *
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* *
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**************************************************************************
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* *
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* File: timeout.yap *
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* Last rev: 5/12/99 *
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* mods: *
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* comments: Goal within timeout *
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* *
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*************************************************************************/
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:- module(timeout, [
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time_out/3
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]).
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:- meta_predicate time_out(:,+,-).
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%
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% not the nicest program I've ever seen.
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%
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%
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% I cannot use setup_call_cleanup because I can only take interrupts *after* I set up
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% the catcher, so I have to do the dirty deed myself.
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%
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time_out(Goal, Time, Result) :-
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T is Time//1000,
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UT is (Time mod 1000)*1000,
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yap_hacks:disable_interrupts,
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% enable alarm
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alarm(T.UT,throw(time_out),_),
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% launch goal and wait for signal
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catch( run_goal(Goal, Result0),
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time_out,
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Result0 = time_out ),
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Result = Result0.
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run_goal(Goal, Result0) :-
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% we can only enable interrupts after alarm was been enabled.
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yap_hacks:enable_interrupts,
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Result0 = success,
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call(Goal),
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!,
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% make sure we're not getting an extraneous interrupt if we terminate early....
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yap_hacks:disable_interrupts.
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alarm(0,_,_),
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true.
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run_goal(Goal, Result0) :-
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yap_hacks:disable_interrupts,
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% make sure we're not getting an extraneous interrupt if we terminate early....
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alarm(0,_,_),
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fail.
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complete_time_out :-
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alarm(0,_,_),
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yap_hacks:enable_interrupts.
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