minix/kernel/system/do_setalarm.c
2005-08-22 15:23:47 +00:00

74 lines
2.7 KiB
C

/* The system call implemented in this file:
* m_type: SYS_SETALARM
*
* The parameters for this system call are:
* m2_l1: ALRM_EXP_TIME (alarm's expiration time)
* m2_i2: ALRM_ABS_TIME (expiration time is absolute?)
* m2_l1: ALRM_TIME_LEFT (return seconds left of previous)
*/
#include "../system.h"
#if USE_SETALARM
FORWARD _PROTOTYPE( void cause_alarm, (timer_t *tp) );
/*===========================================================================*
* do_setalarm *
*===========================================================================*/
PUBLIC int do_setalarm(m_ptr)
message *m_ptr; /* pointer to request message */
{
/* A process requests a synchronous alarm, or wants to cancel its alarm. */
register struct proc *rp; /* pointer to requesting process */
int proc_nr; /* which process wants the alarm */
long exp_time; /* expiration time for this alarm */
int use_abs_time; /* use absolute or relative time */
timer_t *tp; /* the process' timer structure */
clock_t uptime; /* placeholder for current uptime */
/* Extract shared parameters from the request message. */
exp_time = m_ptr->ALRM_EXP_TIME; /* alarm's expiration time */
use_abs_time = m_ptr->ALRM_ABS_TIME; /* flag for absolute time */
proc_nr = m_ptr->m_source; /* process to interrupt later */
rp = proc_addr(proc_nr);
if (! (priv(rp)->s_flags & SYS_PROC)) return(EPERM);
/* Get the timer structure and set the parameters for this alarm. */
tp = &(priv(rp)->s_alarm_timer);
tmr_arg(tp)->ta_int = proc_nr;
tp->tmr_func = cause_alarm;
/* Return the ticks left on the previous alarm. */
uptime = get_uptime();
if ((tp->tmr_exp_time != TMR_NEVER) && (uptime < tp->tmr_exp_time) ) {
m_ptr->ALRM_TIME_LEFT = (tp->tmr_exp_time - uptime);
} else {
m_ptr->ALRM_TIME_LEFT = 0;
}
/* Finally, (re)set the timer depending on the expiration time. */
if (exp_time == 0) {
reset_timer(tp);
} else {
tp->tmr_exp_time = (use_abs_time) ? exp_time : exp_time + get_uptime();
set_timer(tp, tp->tmr_exp_time, tp->tmr_func);
}
return(OK);
}
/*===========================================================================*
* cause_alarm *
*===========================================================================*/
PRIVATE void cause_alarm(tp)
timer_t *tp;
{
/* Routine called if a timer goes off and the process requested a synchronous
* alarm. The process number is stored in timer argument 'ta_int'. Notify that
* process with a notification message from CLOCK.
*/
int proc_nr = tmr_arg(tp)->ta_int; /* get process number */
lock_notify(CLOCK, proc_nr); /* notify process */
}
#endif /* USE_SETALARM */