From d6b2a407783dbbd6c9680601da005de0bb0ff37d Mon Sep 17 00:00:00 2001 From: Manuel Novoa III Date: Mon, 17 Jun 2002 09:45:15 +0000 Subject: Commit the new time stuff, even though I haven't made it threadsafe yet. At least people can play with it. Also, fix a buglet in setenv.c. --- libc/misc/time/difftime.c | 64 ----------------------------------------------- 1 file changed, 64 deletions(-) delete mode 100644 libc/misc/time/difftime.c (limited to 'libc/misc/time/difftime.c') diff --git a/libc/misc/time/difftime.c b/libc/misc/time/difftime.c deleted file mode 100644 index 88a9244ba..000000000 --- a/libc/misc/time/difftime.c +++ /dev/null @@ -1,64 +0,0 @@ -/* Copyright (C) 1991, 1994, 1996 Free Software Foundation, Inc. - This file is part of the GNU C Library. - - The GNU C Library is free software; you can redistribute it and/or - modify it under the terms of the GNU Library General Public License as - published by the Free Software Foundation; either version 2 of the - License, or (at your option) any later version. - - The GNU C Library is distributed in the hope that it will be useful, - but WITHOUT ANY WARRANTY; without even the implied warranty of - MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU - Library General Public License for more details. - - You should have received a copy of the GNU Library General Public - License along with the GNU C Library; see the file COPYING.LIB. If not, - write to the Free Software Foundation, Inc., 59 Temple Place - Suite 330, - Boston, MA 02111-1307, USA. */ - -#include -#include -#include - - -/* Return the difference between TIME1 and TIME0. */ -double difftime (time_t time1, time_t time0) -{ - /* Algorithm courtesy Paul Eggert (eggert@twinsun.com). */ - - time_t delta, 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) << ((sizeof (time_t) * CHAR_BIT) - 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; many 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. */ - return delta - 2 * (long double) hibit; -} -- cgit v1.2.3