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Busy-wait without blocking for a period of time
#include <time.h> int nanospin_ns( unsigned long nsec );
libc
Use the -l c option to qcc to link against this library. This library is usually included automatically.
The nanospin_ns() function busy-waits for the number of nanoseconds specified in nsec, without blocking the calling thread.
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The nanospin*() functions are designed for use with
hardware that requires short time delays between accesses.
You should use them to delay only for times less than a few milliseconds.
For longer delays, use the POSIX
timer_*()
functions.
Because of the nature of time measurement, the function might actually wait longer than the specified time. For more information, see the Tick, Tock: Understanding the Neutrino Microkernel's Concept of Time chapter of the QNX Neutrino Programmer's Guide. |
The first time you call nanospin_ns(), the C library invokes nanospin_calibrate() with an argument of 0 (interrupts enabled), if you haven't invoked it directly first.
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A delay of more than a few milliseconds might not work on some processors. For longer delays, use the POSIX timer_*() functions. |
| Safety: | |
|---|---|
| Cancellation point | No |
| Interrupt handler | Read the Caveats |
| Signal handler | Yes |
| Thread | Yes |
You should use busy-waiting only when absolutely necessary for accessing hardware.
It isn't safe to call this function in an interrupt handler if nanospin_calibrate() hasn't been called yet.
nanosleep(), nanospin(), nanospin_calibrate(), nanospin_count(), nanospin_ns_to_count(), sched_yield(), sleep(), timer_create()
Tick, Tock: Understanding the Neutrino Microkernel's Concept of Time chapter of the QNX Neutrino Programmer's Guide
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