From add25498a593c279c09d7825f6d880b6788ce378 Mon Sep 17 00:00:00 2001
From: Jim Meyering <jim@meyering.net>
Date: Tue, 27 Sep 2005 08:40:36 +0000
Subject: [PATCH] (signed_type_or_expr__): Define. (INT_STRLEN_BOUND)
[__GNUC__]: Use a slightly tighter bound for unsigned types.
---
lib/intprops.h | 17 +++++++++++++++--
1 file changed, 15 insertions(+), 2 deletions(-)
diff --git a/lib/intprops.h b/lib/intprops.h
index 65280b159f..34f971cbaa 100644
--- a/lib/intprops.h
+++ b/lib/intprops.h
@@ -53,12 +53,25 @@
? (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))
+#else
+# define signed_type_or_expr__(t) 1
+#endif
+
/* 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;
+ 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 - 1) * 146 / 485 + 2)
+ ((sizeof (t) * CHAR_BIT - signed_type_or_expr__ (t)) * 146 / 485 \
+ + signed_type_or_expr__ (t) + 1)
/* Bound on buffer size needed to represent an integer type or expression T,
including the terminating null. */
--
2.30.2