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/*
* NAME:
* usleep -- This is the precision timer for Test Set
* Automation. It uses the select(2) system
* call to delay for the desired number of
* micro-seconds. This call returns ZERO
* (which is usually ignored) on successful
* completion, -1 otherwise.
*
* ALGORITHM:
* 1) We range check the passed in microseconds and log a
* warning message if appropriate. We then return without
* delay, flagging an error.
* 2) Load the Seconds and micro-seconds portion of the
* interval timer structure.
* 3) Call select(2) with no file descriptors set, just the
* timer, this results in either delaying the proper
* ammount of time or being interupted early by a signal.
*
* HISTORY:
* Added when the need for a subsecond timer was evident.
*
* AUTHOR:
* Michael J. Dyer <mike@sherlock.med.ge.com>
*/
#ifndef HAVE_USLEEP
#include <unistd.h>
#include <stdlib.h>
#include <stdio.h>
#include <errno.h>
#include <time.h>
#include <sys/time.h>
#include <sys/param.h>
#include <sys/types.h>
int
usleep (unsigned long microSeconds)
{
unsigned int Seconds, uSec;
int nfds = 0;
fd_set readfds, writefds, exceptfds;
struct timeval Timer;
if( (microSeconds == (unsigned long) 0) ||
microSeconds > (unsigned long) 4000000 )
{
errno = ERANGE; /* value out of range */
perror( "usleep time out of range ( 0 -> 4000000 ) " );
return -1;
}
Seconds = microSeconds / (unsigned long) 1000000;
uSec = microSeconds % (unsigned long) 1000000;
Timer.tv_sec = Seconds;
Timer.tv_usec = uSec;
if( select( nfds, &readfds, &writefds, &exceptfds, &Timer ) < 0 )
{
perror( "usleep (select) failed" );
return -1;
}
return 0;
}
#endif /* not HAVE_USLEEP */
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