64 lines
2.4 KiB
C
64 lines
2.4 KiB
C
/* This library provides generic watchdog timer management functionality.
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* The functions operate on a timer queue provided by the caller. Note that
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* the timers must use absolute time to allow sorting. The library provides:
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*
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* tmrs_settimer: (re)set a new watchdog timer in the timers queue
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* tmrs_clrtimer: remove a timer from both the timers queue
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* tmrs_exptimers: check for expired timers and run watchdog functions
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*
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* Author:
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* Jorrit N. Herder <jnherder@cs.vu.nl>
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* Adapted from tmr_settimer and tmr_clrtimer in src/kernel/clock.c.
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* Last modified: September 30, 2004.
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*/
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#ifndef _TIMERS_H
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#define _TIMERS_H
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#include <limits.h>
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#include <sys/types.h>
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struct timer;
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typedef void (*tmr_func_t)(struct timer *tp);
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typedef union { int ta_int; long ta_long; void *ta_ptr; } tmr_arg_t;
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/* A timer_t variable must be declare for each distinct timer to be used.
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* The timers watchdog function and expiration time are automatically set
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* by the library function tmrs_settimer, but its argument is not.
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*/
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typedef struct timer
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{
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struct timer *tmr_next; /* next in a timer chain */
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clock_t tmr_exp_time; /* expiration time */
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tmr_func_t tmr_func; /* function to call when expired */
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tmr_arg_t tmr_arg; /* random argument */
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} timer_t;
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/* Used when the timer is not active. */
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#define TMR_NEVER ((clock_t) -1 < 0) ? ((clock_t) LONG_MAX) : ((clock_t) -1)
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#undef TMR_NEVER
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#define TMR_NEVER ((clock_t) LONG_MAX)
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/* These definitions can be used to set or get data from a timer variable. */
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#define tmr_arg(tp) (&(tp)->tmr_arg)
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#define tmr_exp_time(tp) (&(tp)->tmr_exp_time)
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/* Timers should be initialized once before they are being used. Be careful
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* not to reinitialize a timer that is in a list of timers, or the chain
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* will be broken.
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*/
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#define tmr_inittimer(tp) (void)((tp)->tmr_exp_time = TMR_NEVER, \
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(tp)->tmr_next = NULL)
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/* The following generic timer management functions are available. They
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* can be used to operate on the lists of timers. Adding a timer to a list
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* automatically takes care of removing it.
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*/
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_PROTOTYPE( clock_t tmrs_clrtimer, (timer_t **tmrs, timer_t *tp, clock_t *new_head) );
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_PROTOTYPE( void tmrs_exptimers, (timer_t **tmrs, clock_t now, clock_t *new_head) );
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_PROTOTYPE( clock_t tmrs_settimer, (timer_t **tmrs, timer_t *tp,
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clock_t exp_time, tmr_func_t watchdog, clock_t *new_head) );
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#endif /* _TIMERS_H */
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