+/* Verify a requirement at compile-time (unlike assert, which is runtime). */
+#define verify(name, assertion) struct name { char a[(assertion) ? 1 : -1]; }
+
+/* A signed type that is at least one bit wider than int. */
+#if INT_MAX <= LONG_MAX / 2
+typedef long int long_int;
+#else
+typedef long long int long_int;
+#endif
+verify (long_int_is_wide_enough, INT_MAX == INT_MAX * (long_int) 2 / 2);
+
+/* Shift A right by B bits portably, by dividing A by 2**B and
+ truncating towards minus infinity. A and B should be free of side
+ effects, and B should be in the range 0 <= B <= INT_BITS - 2, where
+ INT_BITS is the number of useful bits in an int. GNU code can
+ assume that INT_BITS is at least 32.
+
+ ISO C99 says that A >> B is implementation-defined if A < 0. Some
+ implementations (e.g., UNICOS 9.0 on a Cray Y-MP EL) don't shift
+ right in the usual way when A < 0, so SHR falls back on division if
+ ordinary A >> B doesn't seem to be the usual signed shift. */
+#define SHR(a, b) \
+ ((-1 >> 1 == -1 \
+ && (long_int) -1 >> 1 == -1 \
+ && ((time_t) -1 >> 1 == -1 || ! TYPE_SIGNED (time_t))) \
+ ? (a) >> (b) \
+ : (a) / (1 << (b)) - ((a) % (1 << (b)) < 0))
+
+/* 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 signed integer type T use two's
+ complement, or if T is an unsigned integer type. */
+#define TYPE_TWOS_COMPLEMENT(t) ((t) ~ (t) 0 == (t) -1)
+
+/* True if the arithmetic type T is signed. */