[src/trunk]: src/lib/libc/gen Refactor to fix some signedness problems.

[matt <matt%NetBSD.org@localhost>]

details:   https://anonhg.NetBSD.org/src/rev/54369aeb5d16
branches:  trunk
changeset: 769127:54369aeb5d16
user:      matt <matt%NetBSD.org@localhost>
date:      Wed Aug 31 22:36:36 2011 +0000

description:
Refactor to fix some signedness problems.

diffstat:

 lib/libc/gen/fixunsgen_ieee754.c |  9 +++++----
 1 files changed, 5 insertions(+), 4 deletions(-)

diffs (31 lines):

diff -r fed533e29e55 -r 54369aeb5d16 lib/libc/gen/fixunsgen_ieee754.c
--- a/lib/libc/gen/fixunsgen_ieee754.c  Wed Aug 31 22:27:26 2011 +0000
+++ b/lib/libc/gen/fixunsgen_ieee754.c  Wed Aug 31 22:36:36 2011 +0000
@@ -1,4 +1,4 @@
-/*     $NetBSD: fixunsgen_ieee754.c,v 1.1 2011/07/09 02:30:27 matt Exp $       */
+/*     $NetBSD: fixunsgen_ieee754.c,v 1.2 2011/08/31 22:36:36 matt Exp $       */
 
 /*-
  * Copyright (c) 1992, 1993
@@ -36,7 +36,7 @@
 #include <sys/cdefs.h>
 
 #if !defined(FIXUNSNAME) && defined(LIBC_SCCS) && !defined(lint)
-__RCSID("$NetBSD: fixunsgen_ieee754.c,v 1.1 2011/07/09 02:30:27 matt Exp $");
+__RCSID("$NetBSD: fixunsgen_ieee754.c,v 1.2 2011/08/31 22:36:36 matt Exp $");
 #endif /* LIBC_SCCS and not lint */
 
 #include <stddef.h>
@@ -64,9 +64,10 @@
        /*
         * If it's less than 1 (negative exponent), it's going to round
         * to zero.  If the exponent is so large that it is a multiple of
-        * 2^N, then x module 2^N will be 0.
+        * 2^N, then x module 2^N will be 0.  (we use the fact treating a
+        * negative value as unsigned will be greater than nonnegative value)
         */
-       if (__predict_false(exp < 0 || exp - mant_dig > sizeof(UINTXX_T)*8-1))
+       if (__predict_false((size_t)exp >= mant_dig + sizeof(UINTXX_T)*8))
                return 0;
 
        /*