Busy-wait without blocking for a number of iterations
#include <time.h> void nanospin_count( unsigned long count );
- The number of iterations 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_count() function busy-waits for the number of iterations specified in count. Use nanospin_ns_to_count() to turn a number of nanoseconds into an iteration count suitable for nanospin_count().
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.
Busy-wait for at least 100 nanoseconds:
#include <time.h> #include <sys/syspage.h> unsigned long time = 100; … /* Wake up the hardware, then wait for it to be ready. */ nanospin_count( nanospin_ns_to_count( time ) ); /* Use the hardware. */ …
You should use busy-waiting only when absolutely necessary for accessing hardware.
Last modified: 2014-06-24