text: /*
  ** This file is in the public domain, so clarified as of
  ** 1996-06-05 by Arthur David Olson.
  */
  
  /*LINTLIBRARY*/
  
  #include "private.h"	/* for time_t and TYPE_SIGNED */
  
  double ATTRIBUTE_CONST
  difftime(const time_t time1, const time_t time0)
  {
  	/*
  	** If (sizeof (double) > sizeof (time_t)) simply convert and subtract
  	** (assuming that the larger type has more precision).
  	*/
  	if (sizeof (double) > sizeof (time_t))
  		return (double) time1 - (double) time0;
  	if (!TYPE_SIGNED(time_t)) {
  		/*
  		** The difference of two unsigned values can't overflow
  		** if the minuend is greater than or equal to the subtrahend.
  		*/
  		if (time1 >= time0)
  			return            time1 - time0;
  		else	return -(double) (time0 - time1);
  	}
  	/*
  	** Handle cases where both time1 and time0 have the same sign
  	** (meaning that their difference cannot overflow).
  	*/
  	if ((time1 < 0) == (time0 < 0))
  		return time1 - time0;
  	/*
  	** time1 and time0 have opposite signs.
  	** Punt if uintmax_t is too narrow.
  	** This suffers from double rounding; attempt to lessen that
  	** by using long double temporaries.
  	*/
  	if (sizeof (uintmax_t) < sizeof (time_t))
  		return (long double) time1 - (long double) time0;
  	/*
  	** Stay calm...decent optimizers will eliminate the complexity below.
  	*/
  	if (time1 >= 0 /* && time0 < 0 */)
  		return    (uintmax_t) time1 + (uintmax_t) (-1 - time0) + 1;
  	return -(double) ((uintmax_t) time0 + (uintmax_t) (-1 - time1) + 1);
  }
  