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\ Hypervisor Software File: timer.fth
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id: @(#)timer.fth 1.1 04/09/07
purpose: Timer utility functions
copyright: Copyright 2004 Sun Microsystems, Inc.  All Rights Reserved
copyright: Use is subject to license terms.

headerless

struct
   /l  field   >tm-start	\ Time this entry was made
   /l  field   >tm-expire	\ Time this timer expires
constant /timer

\ Set timer event.
: set-timer ( timer interval -- )
   get-msecs tuck +  rot tuck >tm-expire l!  >tm-start l!
;

\ Clear timer event. Return time elapsed since event entry was made.
: clear-timer ( timer -- timespent )
   get-msecs  over >tm-start l@ -  swap		( timespent timer )
   0  over >tm-expire  l!			( timespent timer )
   0  swap >tm-start   l!			( timespent )
;

\ Get time elapsed since the timer event entry was made.
: get-timer ( timer -- timespent )
   >tm-start l@  get-msecs  swap -
;

\ Check if timer has expired.
: timer-expired? ( timer -- flag )
   >tm-expire l@  ?dup if  get-msecs <  else  false  then
;

\ Check if timer is in use. 
: timer-running? ( timer -- flag )  >tm-expire l@ 0<> ;

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