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mktime: remove incorrect attempt at unusual arithmetics

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* time/mktime.c (TYPE_ONES_COMPLEMENT, TYPE_SIGNED_MAGNITUDE): Remove.
The code didn't really work on such machines anyway.
(TYPE_MINIMUM): Assume two's complement.
(twos_complement_arithmetic): Verify that long_int and time_t
are two's complement (or unsigned, in the latter case).
This commit is contained in:
Paul Eggert 2012-03-16 03:00:48 -07:00
parent 03cf7fe31b
commit 6860543348
2 changed files with 13 additions and 9 deletions
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7
ChangeLog
View File

@ -1,5 +1,12 @@
2012-05-23 Paul Eggert <eggert@cs.ucla.edu>
mktime: remove incorrect attempt at unusual arithmetics
* time/mktime.c (TYPE_ONES_COMPLEMENT, TYPE_SIGNED_MAGNITUDE): Remove.
The code didn't really work on such machines anyway.
(TYPE_MINIMUM): Assume two's complement.
(twos_complement_arithmetic): Verify that long_int and time_t
are two's complement (or unsigned, in the latter case).
mktime: check signed shifts on long_int and time_t, too
* time/mktime.c (SHR): Check that shifts work as desired
on the types long_int and time_t too, as SHR is used on

15
time/mktime.c
View File

@ -104,12 +104,8 @@ verify (long_int_is_wide_enough, INT_MAX == INT_MAX * (long_int) 2 / 2);
#define TYPE_IS_INTEGER(t) ((t) 1.5 == 1)
/* True if negative values of the signed integer type T use two's
complement, ones' complement, or signed magnitude representation,
respectively. Much GNU code assumes two's complement, but some
people like to be portable to all possible C hosts. */
complement, or if T is an unsigned integer type. */
#define TYPE_TWOS_COMPLEMENT(t) ((t) ~ (t) 0 == (t) -1)
#define TYPE_ONES_COMPLEMENT(t) ((t) ~ (t) 0 == 0)
#define TYPE_SIGNED_MAGNITUDE(t) ((t) ~ (t) 0 < (t) -1)
/* True if the arithmetic type T is signed. */
#define TYPE_SIGNED(t) (! ((t) 0 < (t) -1))
@ -121,9 +117,7 @@ verify (long_int_is_wide_enough, INT_MAX == INT_MAX * (long_int) 2 / 2);
#define TYPE_MINIMUM(t) \
((t) (! TYPE_SIGNED (t) \
? (t) 0 \
: TYPE_SIGNED_MAGNITUDE (t) \
? ~ (t) 0 \
: ~ (t) 0 << (sizeof (t) * CHAR_BIT - 1)))
: ~ TYPE_MAXIMUM (t)))
#define TYPE_MAXIMUM(t) \
((t) (! TYPE_SIGNED (t) \
? (t) -1 \
@ -138,7 +132,10 @@ verify (long_int_is_wide_enough, INT_MAX == INT_MAX * (long_int) 2 / 2);
#define TIME_T_MIDPOINT (SHR (TIME_T_MIN + TIME_T_MAX, 1) + 1)
verify (time_t_is_integer, TYPE_IS_INTEGER (time_t));
verify (twos_complement_arithmetic, TYPE_TWOS_COMPLEMENT (int));
verify (twos_complement_arithmetic,
(TYPE_TWOS_COMPLEMENT (int)
&& TYPE_TWOS_COMPLEMENT (long_int)
&& TYPE_TWOS_COMPLEMENT (time_t)));
#define EPOCH_YEAR 1970
#define TM_YEAR_BASE 1900