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/*

 *  posixtimespecsubtract.c,v 1.3 2001/01/24 14:17:28 joel Exp

 */

#if HAVE_CONFIG_H

#include "config.h"

#endif

#include <assert.h>

#include <time.h>

#include <errno.h>

#include <rtems/system.h>

#include <rtems/score/isr.h>

#include <rtems/score/thread.h>

#include <rtems/score/tod.h>

#include <rtems/seterr.h>

#include <rtems/posix/time.h>

/*PAGE

 *

 *  _POSIX_Timespec_subtract

 */

void _POSIX_Timespec_subtract(

  const struct timespec *the_start,

  const struct timespec *end,

  struct timespec *result

)

{

  struct timespec  start_struct = *the_start;

  struct timespec *start = &start_struct;

  unsigned int nsecs_per_sec = TOD_NANOSECONDS_PER_SECOND;

  if (end->tv_nsec < start->tv_nsec) {

    int seconds = (start->tv_nsec - end->tv_nsec) / nsecs_per_sec + 1;

    start->tv_nsec -= nsecs_per_sec * seconds;

    start->tv_sec += seconds;

  }

  if (end->tv_nsec - start->tv_nsec > nsecs_per_sec) {

    int seconds = (start->tv_nsec - end->tv_nsec) / nsecs_per_sec;

    start->tv_nsec += nsecs_per_sec * seconds;

    start->tv_sec -= seconds;

  }

  result->tv_sec  = end->tv_sec - start->tv_sec;

  result->tv_nsec = end->tv_nsec - start->tv_nsec;

}