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-rw-r--r--time/difftime.c74
1 files changed, 0 insertions, 74 deletions
diff --git a/time/difftime.c b/time/difftime.c
deleted file mode 100644
index 18325862d..000000000
--- a/time/difftime.c
+++ /dev/null
@@ -1,74 +0,0 @@
-#ifndef lint
-#ifndef NOID
-static char elsieid[] = "@(#)difftime.c 7.5";
-#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 = 1;
- while ((hibit <<= 1) > 0)
- continue;
- /*
- ** 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;
-}