From b6097b0f23253c9f7210b023df657e2bb320cbd3 Mon Sep 17 00:00:00 2001 From: Paul Eggert Date: Wed, 9 Mar 2005 23:22:50 +0000 Subject: [PATCH] Add TYPE_ONES_COMPLEMENT and TYPE_SIGNED_MAGNITUDE, and use less-tricky TYPE_MINIMUM and TYPE_MAXIMUM. --- lib/intprops.h | 30 ++++++++++++++++++++---------- 1 file changed, 20 insertions(+), 10 deletions(-) diff --git a/lib/intprops.h b/lib/intprops.h index cd1c17212..eb79ac22d 100644 --- a/lib/intprops.h +++ b/lib/intprops.h @@ -27,21 +27,31 @@ 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 negative values of the signed integer type T use twos + complement, ones complement, or signed magnitude representation, + respectively. Much GNU code assumes twos complement, but some + people like to be portable to all possible C hosts. */ +#define TYPE_TWOS_COMPLEMENT(t) ((t) ~ (t) 0 == (t) -1) +#define TYPE_ONES_COMPLEMENT(t) ((t) ~ (t) 0 == 0) +#define TYPE_SIGNED_MAGNITUDE(t) ((t) ~ (t) 0 < (t) -1) /* True if the arithmetic type T is signed. */ #define TYPE_SIGNED(t) (! ((t) 0 < (t) -1)) /* 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))) + 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)))) /* Bound on length of the string representing an integer value or type T. Subtract 1 for the sign bit if t is signed; log10 (2.0) < 146/485; -- 2.11.0