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Suspend a thread for a given number of microseconds
#include <unistd.h>
int usleep( useconds_t useconds );
- useconds
- The number of microseconds that you want to process to sleep for.
This must be less than 1,000,000.
libc
Use the -l c option to
qcc
to link against this library.
This library is usually included automatically.
The usleep() function suspends the calling thread until
useconds microseconds of realtime have elapsed, or until
a signal that isn't ignored is received. The time spent suspended could be
longer than the requested amount due to the nature of
time measurement (see the
Tick, Tock: Understanding the Neutrino Microkernel's Concept of Time
chapter of the QNX Neutrino Programmer's Guide),
or due to the scheduling of other, higher-priority threads.
If useconds is
0, usleep() has no effect.
- 0
- Success.
- -1
- An error occurred (errno is set).
- EAGAIN
- No timer resources are available to satisfy the request.
- EINVAL
- The useconds argument is too large.
/*
* The following program sleeps for the
* number of microseconds specified in argv[1].
*/
#include <stdlib.h>
#include <unistd.h>
int main( int argc, char **argv )
{
useconds_t microseconds;
microseconds = (useconds_t)strtol( argv[1], NULL, 0 );
if( usleep( microseconds ) == 0 ) {
return EXIT_SUCCESS;
}
return EXIT_FAILURE;
}
POSIX 1003.1 XSI
Safety: | |
Cancellation point |
Yes |
Interrupt handler |
No |
Signal handler |
Yes |
Thread |
Yes |
alarm(),
delay(),
nanosleep(),
sigaction(),
sleep(),
timer_create(),
timer_delete(),
timer_getoverrun(),
timer_gettime(),
timer_settime(),
ualarm()
Tick, Tock: Understanding the Neutrino Microkernel's Concept of Time
chapter of the QNX Neutrino Programmer's Guide
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