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 * National Laboratory for Applied Network Research 
 * National Center for Supercomputing Applications 
 * University of Illinois at Urbana-Champaign 
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 *
 * delay.c
 * by Mark Gates <mgates@nlanr.net>
 * -------------------------------------------------------------------
 * accurate microsecond delay
 * ------------------------------------------------------------------- */

#include "Timestamp.hpp"
#include "util.h"
#include "delay.hpp"

/* -------------------------------------------------------------------
 * A micro-second delay function using POSIX nanosleep(). This allows a
 * higher timing resolution (under Linux e.g. it uses hrtimers), does not
 * affect any signals, and will use up remaining time when interrupted.
 * ------------------------------------------------------------------- */
void delay_loop(unsigned long usec)
{
    struct timespec requested, remaining;

    requested.tv_sec  = 0;
    requested.tv_nsec = usec * 1000L;

    while (nanosleep(&requested, &remaining) == -1)
        if (errno == EINTR)
            requested = remaining;
        else {
            WARN_errno(1, "nanosleep");
            break;
        }
}