/* Convert a `struct tm' to a time_t value.
- Copyright (C) 1993-1999, 2002, 2003, 2004 Free Software Foundation, Inc.
+ Copyright (C) 1993-1999, 2002, 2003, 2004, 2005 Free Software Foundation,
+ Inc.
This file is part of the GNU C Library.
Contributed by Paul Eggert (eggert@twinsun.com).
? (a) >> (b) \
: (a) / (1 << (b)) - ((a) % (1 << (b)) < 0))
-/* The extra casts work around common compiler bugs. */
+/* The extra casts in the following macros work around compiler bugs,
+ e.g., in Cray C 5.0.3.0. */
+
+/* True if the arithmetic type T is an integer type. bool counts as
+ an integer. */
+#define TYPE_IS_INTEGER(t) ((t) 1.5 == 1)
+
+/* True if negative values of the integer type T use twos complement
+ representation. */
+#define TYPE_TWOS_COMPLEMENT(t) ((t) - (t) 1 == (t) ((t) ~ (t) 1 + (t) 1))
+
+/* True if the arithmetic type T is signed. */
#define TYPE_SIGNED(t) (! ((t) 0 < (t) -1))
-/* The outer cast is needed to work around a bug in Cray C 5.0.3.0.
- It is necessary at least when t == time_t. */
+
+/* The maximum and minimum values for the integer type T. These
+ macros have undefined behavior if T is signed and has padding bits
+ (i.e., bits that do not contribute to the value), or if T uses
+ signed-magnitude representation. If this is a problem for you,
+ please let us know how to fix it for your host. */
#define TYPE_MINIMUM(t) ((t) (TYPE_SIGNED (t) \
? ~ (t) 0 << (sizeof (t) * CHAR_BIT - 1) : (t) 0))
#define TYPE_MAXIMUM(t) ((t) (~ (t) 0 - TYPE_MINIMUM (t)))
/* Verify a requirement at compile-time (unlike assert, which is runtime). */
#define verify(name, assertion) struct name { char a[(assertion) ? 1 : -1]; }
-verify (time_t_is_integer, (time_t) 0.5 == 0);
-verify (twos_complement_arithmetic, -1 == ~1 + 1);
+verify (time_t_is_integer, TYPE_IS_INTEGER (time_t));
+verify (twos_complement_arithmetic, TYPE_TWOS_COMPLEMENT (int));
/* The code also assumes that signed integer overflow silently wraps
around, but this assumption can't be stated without causing a
diagnostic on some hosts. */