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authorTom Lane2004-05-21 05:08:06 +0000
committerTom Lane2004-05-21 05:08:06 +0000
commit63bd0db12199c5df043e1dea0f2b574f622b3a4c (patch)
treedbafdb6e4541162ad369dbfeca24cbd62aefddcc /src/timezone/difftime.c
parent260b513fc37b6ed2df51586c487d0832b89d0d70 (diff)
Integrate src/timezone library for all platforms. There is more we can
and should do now that we control our own destiny for timezone handling, but this commit gets the bulk of the picayune diffs in place. Magnus Hagander and Tom Lane.
Diffstat (limited to 'src/timezone/difftime.c')
-rw-r--r--src/timezone/difftime.c84
1 files changed, 0 insertions, 84 deletions
diff --git a/src/timezone/difftime.c b/src/timezone/difftime.c
deleted file mode 100644
index 57b88deafee..00000000000
--- a/src/timezone/difftime.c
+++ /dev/null
@@ -1,84 +0,0 @@
-#include "pgtz.h"
-/*
-** This file is in the public domain, so clarified as of
-** June 5, 1996 by Arthur David Olson (arthur_david_olson@nih.gov).
-*/
-
-#ifndef lint
-#ifndef NOID
-static char elsieid[] = "@(#)difftime.c 7.9";
-#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;
-
- {
- time_t tt;
- double d;
- long_double ld;
-
- if (sizeof tt < sizeof d)
- return (double) time1 - (double) time0;
- if (sizeof tt < sizeof ld)
- 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;
-}