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! ---------------------------------------------------------------------------- !
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! Daemons.h by Andrew Plotkin and Roger Firth (roger.firth@tesco.net,
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! to whom all problems should be notified).
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! Converted to Inform 6 and Glulx by Roger Firth.
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! Original version for Inform 5.5 by Andrew Plotkin.
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! This file is in the public domain.
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! ---------------------------------------------------------------------------- !
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! Installation: add the lines:
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! Replace StartDaemon;
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! before your Include "Parser" line. Also, add the line:
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! near the end of your game AFTER you've defined an object which uses a
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! "daemon_priority" property.
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! ---------------------------------------------------------------------------- !
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! This is a package which you can include to make the daemons and timers of
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! the Inform libraries behave predictably. They will execute in the order
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! defined by the optional "daemon_priority" property of each object in the
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! daemon/timer list. Higher priorities go first; if priorities are equal,
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! they execute in the order in which they were started up. The default
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! daemon_priority is zero, but you can assign any numerical value to the
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! property, including negative ones.
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! There are a few restrictions:
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! - daemon_priority must be a simple variable containing a number; it cannot
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! be an embedded routine which returns a number.
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! - you should assign a new value to a daemon_priority property only while
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! the object's daemon/timer is *not* running. This means that if an object
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! has both a daemon and a timer, they must run at the same priority.
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! - it is illegal to call StartDaemon() or StartTimer() from inside a
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! daemon or timer routine. It *is* legal to call StopDaemon() or
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! StopTimer() at any time.
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! A bonus utility routine IsDaemonActive(obj) returns 1 if obj currently has
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! an active daemon, 2 for an active timer, 3 for both, 0 for neither.
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! Here is an example daemon:
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! with daemon_priority 1000,
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! ---------------------------------------------------------------------------- !
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#ifndef WORD_HIGHBIT; ! Is already defined in Glulx compiler.
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Constant WORD_HIGHBIT $8000; ! Topmost bit in Z-machine word, used by
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#endif; ! the Library to flag daemons in the_timers.
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! GetPriority() is a utility routine which masks out the daemon-or-timer flag
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! and fetches the value of the daemon_priority property.
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obj = obj & ~WORD_HIGHBIT;
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if (obj provides daemon_priority) return obj.daemon_priority;
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! StartDaemonOrTimer() is a utility routine which inserts the given object
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! in the_timers list, at the position defined by its daemon_priority. That is,
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! the object is inserted after all objects with a greater-or-equal priority,
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! and before all objects with a lesser priority.
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[ StartDaemonOrTimer obj
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! If obj already in the list, do nothing
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for (i=0 : i<active_timers : i++)
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if (the_timers-->i == obj) rfalse;
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! Compress the list, removing empty slots
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for (i=0,j=0 : i<active_timers : i++)
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the_timers-->j = the_timers-->i;
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! Check for capacity to run another daemon/timer
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if (active_timers == MAX_TIMERS) { RunTimeError(4); rfalse; }
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! Find the first slot at a lower priority
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for (i=0 : i<active_timers : i++)
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if (GetPriority(the_timers-->i) < GetPriority(obj)) break;
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! Shift upwards that slot and those above it
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for ( : j>i : j--) the_timers-->j = the_timers-->(j-1);
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! Insert the new object
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the_timers-->i = obj;
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return ++active_timers;
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! Replacement for the standard Library version of StartDaemon().
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StartDaemonOrTimer(obj+WORD_HIGHBIT);
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! Replacement for the standard Library version of StartTimer().
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[ StartTimer obj timer;
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if (obj.&time_left == 0) { RunTimeError(5, obj); return; }
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if (StartDaemonOrTimer(obj)) obj.time_left = timer;
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! ---------------------------------------------------------------------------- !
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! IsDaemonActive() tests whether an object's daemon and/or timer is
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! currently scheduled to run.
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for (i=0,j=0 : i<active_timers : i++) {
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if (the_timers-->i == obj) j = 2;
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else if (the_timers-->i == obj + WORD_HIGHBIT) j++;
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! ---------------------------------------------------------------------------- !
added
removed
inform-6.31.1/include/daemons.h
