/* intprops.h -- properties of integer types
- Copyright (C) 2001, 2002, 2003, 2004, 2005 Free Software Foundation, Inc.
+ Copyright (C) 2001-2005, 2009-2011 Free Software Foundation, Inc.
This program is free software: you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
/* Written by Paul Eggert. */
+#ifndef _GL_INTPROPS_H
+#define _GL_INTPROPS_H
+
#include <limits.h>
/* The extra casts in the following macros work around compiler bugs,
macros have undefined behavior if T is signed and has padding bits.
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 \
- : TYPE_SIGNED_MAGNITUDE (t) \
- ? ~ (t) 0 \
- : ~ (t) 0 << (sizeof (t) * CHAR_BIT - 1)))
-#define TYPE_MAXIMUM(t) \
- ((t) (! TYPE_SIGNED (t) \
- ? (t) -1 \
- : ~ (~ (t) 0 << (sizeof (t) * CHAR_BIT - 1))))
-
-/* Return zero if T can be determined to be an unsigned type.
- Otherwise, return 1.
- When compiling with GCC, INT_STRLEN_BOUND uses this macro to obtain a
- tighter bound. Otherwise, it overestimates the true bound by one byte
- when applied to unsigned types of size 2, 4, 16, ... bytes.
- The symbol signed_type_or_expr__ is private to this header file. */
-#if __GNUC__ >= 2
-# define signed_type_or_expr__(t) TYPE_SIGNED (__typeof__ (t))
+#define TYPE_MINIMUM(t) \
+ ((t) (! TYPE_SIGNED (t) \
+ ? (t) 0 \
+ : TYPE_SIGNED_MAGNITUDE (t) \
+ ? ~ (t) 0 \
+ : ~ TYPE_MAXIMUM (t)))
+#define TYPE_MAXIMUM(t) \
+ ((t) (! TYPE_SIGNED (t) \
+ ? (t) -1 \
+ : ((((t) 1 << (sizeof (t) * CHAR_BIT - 2)) - 1) * 2 + 1)))
+
+/* Return 1 if the __typeof__ keyword works. This could be done by
+ 'configure', but for now it's easier to do it by hand. */
+#if 2 <= __GNUC__ || 0x5110 <= __SUNPRO_C
+# define _GL_HAVE___TYPEOF__ 1
+#else
+# define _GL_HAVE___TYPEOF__ 0
+#endif
+
+/* Return 1 if the integer type or expression T might be signed. Return 0
+ if it is definitely unsigned. This macro does not evaluate its argument,
+ and expands to an integer constant expression. */
+#if _GL_HAVE___TYPEOF__
+# define _GL_SIGNED_TYPE_OR_EXPR(t) TYPE_SIGNED (__typeof__ (t))
#else
-# define signed_type_or_expr__(t) 1
+# define _GL_SIGNED_TYPE_OR_EXPR(t) 1
#endif
+/* Bound on length of the string representing an unsigned integer
+ value representable in B bits. log10 (2.0) < 146/485. The
+ smallest value of B where this bound is not tight is 2621. */
+#define INT_BITS_STRLEN_BOUND(b) (((b) * 146 + 484) / 485)
+
/* Bound on length of the string representing an integer type or expression T.
- Subtract 1 for the sign bit if T is signed; log10 (2.0) < 146/485;
- add 1 for integer division truncation; add 1 more for a minus sign
- if needed. */
-#define INT_STRLEN_BOUND(t) \
- ((sizeof (t) * CHAR_BIT - signed_type_or_expr__ (t)) * 146 / 485 \
- + signed_type_or_expr__ (t) + 1)
+ Subtract 1 for the sign bit if T is signed, and then add 1 more for
+ a minus sign if needed.
+
+ Because _GL_SIGNED_TYPE_OR_EXPR sometimes returns 0 when its argument is
+ signed, this macro may overestimate the true bound by one byte when
+ applied to unsigned types of size 2, 4, 16, ... bytes. */
+#define INT_STRLEN_BOUND(t) \
+ (INT_BITS_STRLEN_BOUND (sizeof (t) * CHAR_BIT \
+ - _GL_SIGNED_TYPE_OR_EXPR (t)) \
+ + _GL_SIGNED_TYPE_OR_EXPR (t))
/* Bound on buffer size needed to represent an integer type or expression T,
including the terminating null. */
#define INT_BUFSIZE_BOUND(t) (INT_STRLEN_BOUND (t) + 1)
+
+#endif /* _GL_INTPROPS_H */
projects / gnulib.git / blobdiff