Busy-wait without blocking for a period of time
#include <time.h> int nanospin_ns( unsigned long nsec );
- The number of nanoseconds that you want to busy-wait for.
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.
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 Microkernel's Concept of Time chapter of the BlackBerry 10 OS 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.
- The delay specified by nsec is greater than
A delay of more than a few milliseconds might not work on some processors. For longer delays, use the POSIX timer_*() functions.
- A too-high rate of interrupts occurred during the calibration routine.
- This system's startup-* program didn't initialize the timing information necessary to use nanospin_ns().
|Interrupt handler||Read the Caveats|
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.
Last modified: 2014-06-24