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Revision explicitly promote to double. |

/* $NetBSD: difftime.c,v 1.22 2019/04/04 19:25:38 christos Exp $ */ /* Return the difference between two timestamps. */ /* ** This file is in the public domain, so clarified as of ** 1996-06-05 by Arthur David Olson. */ #include <sys/cdefs.h> #if defined(LIBC_SCCS) && !defined(lint) #if 0 static char elsieid[] = "@(#)difftime.c 8.1"; #else __RCSID("$NetBSD: difftime.c,v 1.22 2019/04/04 19:25:38 christos Exp $"); #endif #endif /* LIBC_SCCS and not lint */ /*LINTLIBRARY*/ #include "private.h" /* for time_t and TYPE_SIGNED */ /* Return -X as a double. Using this avoids casting to 'double'. */ static double dminus(double x) { return -x; } double difftime(time_t time1, time_t time0) { /* ** If double is large enough, simply convert and subtract ** (assuming that the larger type has more precision). */ /*CONSTCOND*/ if (sizeof (time_t) < sizeof (double)) { double t1 = time1, t0 = time0; return t1 - t0; } /* ** The difference of two unsigned values can't overflow ** if the minuend is greater than or equal to the subtrahend. */ if (!TYPE_SIGNED(time_t)) return time0 <= time1 ? time1 - time0 : dminus((double)(time0 - time1)); /* Use uintmax_t if wide enough. */ /*CONSTCOND*/ if (sizeof (time_t) <= sizeof (uintmax_t)) { uintmax_t t1 = time1, t0 = time0; return time0 <= time1 ? t1 - t0 : dminus((double)(t0 - t1)); } /* ** 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; /* ** The values have opposite signs and uintmax_t is too narrow. ** This suffers from double rounding; attempt to lessen that ** by using long double temporaries. */ { long double t1 = time1, t0 = time0; return t1 - t0; } }