45 lines
1.4 KiB
C
45 lines
1.4 KiB
C
#include "utils.h"
|
|
|
|
/*===========================================================================*
|
|
* tickdelay *
|
|
*===========================================================================*/
|
|
PUBLIC int tickdelay(ticks)
|
|
long ticks; /* number of ticks to wait */
|
|
{
|
|
/* This function uses the synchronous alarm to delay for a while. This works
|
|
* even if a previous synchronous alarm was scheduled, because the remaining
|
|
* tick of the previous alarm are returned so that it can be rescheduled.
|
|
* Note however that a long tick_delay (longer than the remaining time of the
|
|
* previous) alarm will also delay the previous alarm.
|
|
*/
|
|
message m, m_alarm;
|
|
clock_t time_left;
|
|
int s;
|
|
|
|
if (ticks <= 0) return; /* check for robustness */
|
|
|
|
m.m_type = SYS_SYNCALRM; /* request a synchronous alarm */
|
|
m.ALRM_PROC_NR = SELF; /* SELF means this process nr */
|
|
m.ALRM_EXP_TIME = ticks; /* request message after ticks */
|
|
m.ALRM_ABS_TIME = 0; /* ticks are relative to now */
|
|
s = _taskcall(SYSTASK, SYS_SYNCALRM, &m);
|
|
if (s != OK) return(s);
|
|
|
|
receive(CLOCK,&m_alarm); /* await synchronous alarm */
|
|
|
|
/* Check if we must reschedule the current alarm. */
|
|
if (m.ALRM_TIME_LEFT > 0) {
|
|
m.ALRM_EXP_TIME = m.ALRM_TIME_LEFT - ticks;
|
|
if (m.ALRM_EXP_TIME <= 0)
|
|
m.ALRM_EXP_TIME = 1;
|
|
s = _taskcall(SYSTASK, SYS_SYNCALRM, &m);
|
|
}
|
|
|
|
return(s);
|
|
}
|
|
|
|
|
|
|
|
|
|
|