Loading...
stdtime/difftime.c Libc-262 /dev/null
--- Libc/Libc-262/stdtime/difftime.c
+++ /dev/null
@@ -1,79 +0,0 @@
-/*
-** This file is in the public domain, so clarified as of
-** June 5, 1996 by Arthur David Olson (arthur_david_olson@nih.gov).
-**
-** $FreeBSD: src/lib/libc/stdtime/difftime.c,v 1.4.8.1 2001/03/05 11:37:21 obrien Exp $
-*/
-
-#ifndef lint
-#ifndef NOID
-static char	elsieid[] = "@(#)difftime.c	7.7";
-#endif /* !defined NOID */
-#endif /* !defined lint */
-
-/*LINTLIBRARY*/
-
-#include "private.h"
-
-/*
-** Algorithm courtesy Paul Eggert (eggert@twinsun.com).
-*/
-
-#ifdef HAVE_LONG_DOUBLE
-#define long_double	long double
-#endif /* defined HAVE_LONG_DOUBLE */
-#ifndef HAVE_LONG_DOUBLE
-#define long_double	double
-#endif /* !defined HAVE_LONG_DOUBLE */
-
-double
-difftime(time1, time0)
-const time_t	time1;
-const time_t	time0;
-{
-	time_t	delta;
-	time_t	hibit;
-
-	if (sizeof(time_t) < sizeof(double))
-		return (double) time1 - (double) time0;
-	if (sizeof(time_t) < sizeof(long_double))
-		return (long_double) time1 - (long_double) time0;
-	if (time1 < time0)
-		return -difftime(time0, time1);
-	/*
-	** As much as possible, avoid loss of precision
-	** by computing the difference before converting to double.
-	*/
-	delta = time1 - time0;
-	if (delta >= 0)
-		return delta;
-	/*
-	** Repair delta overflow.
-	*/
-	hibit = (~ (time_t) 0) << (TYPE_BIT(time_t) - 1);
-	/*
-	** The following expression rounds twice, which means
-	** the result may not be the closest to the true answer.
-	** For example, suppose time_t is 64-bit signed int,
-	** long_double is IEEE 754 double with default rounding,
-	** time1 = 9223372036854775807 and time0 = -1536.
-	** Then the true difference is 9223372036854777343,
-	** which rounds to 9223372036854777856
-	** with a total error of 513.
-	** But delta overflows to -9223372036854774273,
-	** which rounds to -9223372036854774784, and correcting
-	** this by subtracting 2 * (long_double) hibit
-	** (i.e. by adding 2**64 = 18446744073709551616)
-	** yields 9223372036854776832, which
-	** rounds to 9223372036854775808
-	** with a total error of 1535 instead.
-	** This problem occurs only with very large differences.
-	** It's too painful to fix this portably.
-	** We are not alone in this problem;
-	** some C compilers round twice when converting
-	** large unsigned types to small floating types,
-	** so if time_t is unsigned the "return delta" above
-	** has the same double-rounding problem with those compilers.
-	*/
-	return delta - 2 * (long_double) hibit;
-}