ISO C99 wants also some functions that operate on 'float', not only on
'double' or 'long double'. I'm not sure whether a conversion of a signalling
NaN(f) to a 'double' value will crash the program or not, so better be careful:
I'm adding a module 'isnanf' that test a 'float' for NaN.
2007-04-06 Bruno Haible <[EMAIL PROTECTED]>
* modules/isnanf-nolibm: New file.
* lib/isnanf.h: New file.
* lib/isnanf.c: New file.
* lib/isnan.c: Consider the USE_FLOAT macro.
* m4/isnanf.m4: New file.
============================== modules/isnanf-nolibm ==========================
Description:
isnanf() function: test for NaN, without requiring libm.
Files:
lib/isnanf.h
lib/isnanf.c
lib/isnan.c
lib/float+.h
m4/isnanf.m4
Depends-on:
fpieee
configure.ac:
gl_FUNC_ISNANF_NO_LIBM
Makefile.am:
Include:
#include "isnanf.h"
License:
LGPL
Maintainer:
Bruno Haible
================================ lib/isnanf.h =================================
/* Test for NaN that does not need libm.
Copyright (C) 2007 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
the Free Software Foundation; either version 2, or (at your option)
any later version.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License along
with this program; if not, write to the Free Software Foundation,
Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA. */
#if HAVE_ISNANF_IN_LIBC
/* Get declaration of isnan macro or (older) isnanf function. */
# include <math.h>
# ifdef isnan
# undef isnanf
# define isnanf(x) isnan ((float)(x))
# endif
#else
/* Test whether X is a NaN. */
# undef isnanf
# define isnanf rpl_isnanf
extern int isnanf (float x);
#endif
================================ lib/isnanf.c =================================
/* Test for NaN that does not need libm.
Copyright (C) 2007 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
the Free Software Foundation; either version 2, or (at your option)
any later version.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License along
with this program; if not, write to the Free Software Foundation,
Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA. */
/* Written by Bruno Haible <[EMAIL PROTECTED]>, 2007. */
#define USE_FLOAT
#include "isnan.c"
================================ m4/isnanf.m4 =================================
# isnanf.m4 serial 1
dnl Copyright (C) 2007 Free Software Foundation, Inc.
dnl This file is free software; the Free Software Foundation
dnl gives unlimited permission to copy and/or distribute it,
dnl with or without modifications, as long as this notice is preserved.
dnl Check how to get or define isnanf() without linking with libm.
AC_DEFUN([gl_FUNC_ISNANF_NO_LIBM],
[
gl_HAVE_ISNANF_NO_LIBM
if test $gl_cv_func_isnanf_no_libm = yes; then
AC_DEFINE([HAVE_ISNANF_IN_LIBC], 1,
[Define if the isnan(float) function is available in libc.])
else
AC_LIBOBJ([isnanf])
gl_FLOAT_EXPONENT_LOCATION
fi
])
dnl Test whether isnanf() can be used without libm.
AC_DEFUN([gl_HAVE_ISNANF_NO_LIBM],
[
AC_CACHE_CHECK([whether isnan(float) can be used without linking with libm],
[gl_cv_func_isnanf_no_libm],
[
AC_TRY_LINK([#include <math.h>
#ifdef isnan
# undef isnanf
# define isnanf(x) isnan ((float)(x))
#endif
float x;],
[return isnanf (x);],
[gl_cv_func_isnanf_no_libm=yes],
[gl_cv_func_isnanf_no_libm=no])
])
])
AC_DEFUN([gl_FLOAT_EXPONENT_LOCATION],
[
AC_CACHE_CHECK([where to find the exponent in a 'float'],
[gl_cv_cc_float_expbit0],
[
AC_TRY_RUN([
#include <float.h>
#include <stddef.h>
#include <stdio.h>
#include <string.h>
#define NWORDS \
((sizeof (float) + sizeof (unsigned int) - 1) / sizeof (unsigned int))
typedef union { float value; unsigned int word[NWORDS]; } memory_float;
static unsigned int ored_words[NWORDS];
static unsigned int anded_words[NWORDS];
static void add_to_ored_words (float x)
{
memory_float m;
size_t i;
/* Clear it first, in case
sizeof (float) < sizeof (memory_float). */
memset (&m, 0, sizeof (memory_float));
m.value = x;
for (i = 0; i < NWORDS; i++)
{
ored_words[i] |= m.word[i];
anded_words[i] &= m.word[i];
}
}
int main ()
{
size_t j;
FILE *fp = fopen ("conftest.out", "w");
if (fp == NULL)
return 1;
for (j = 0; j < NWORDS; j++)
anded_words[j] = ~ (unsigned int) 0;
add_to_ored_words (0.25f);
add_to_ored_words (0.5f);
add_to_ored_words (1.0f);
add_to_ored_words (2.0f);
add_to_ored_words (4.0f);
/* Remove bits that are common (e.g. if representation of the first mantissa
bit is explicit). */
for (j = 0; j < NWORDS; j++)
ored_words[j] &= ~anded_words[j];
/* Now find the nonzero word. */
for (j = 0; j < NWORDS; j++)
if (ored_words[j] != 0)
break;
if (j < NWORDS)
{
size_t i;
for (i = j + 1; i < NWORDS; i++)
if (ored_words[i] != 0)
{
fprintf (fp, "unknown");
return (fclose (fp) != 0);
}
for (i = 0; ; i++)
if ((ored_words[j] >> i) & 1)
{
fprintf (fp, "word %d bit %d", (int) j, (int) i);
return (fclose (fp) != 0);
}
}
fprintf (fp, "unknown");
return (fclose (fp) != 0);
}
],
[gl_cv_cc_float_expbit0=`cat conftest.out`],
[gl_cv_cc_float_expbit0="unknown"],
[gl_cv_cc_double_expbit0="word 0 bit 23"])
rm -f conftest.out
])
case "$gl_cv_cc_float_expbit0" in
word*bit*)
word=`echo "$gl_cv_cc_float_expbit0" | sed -e 's/word //' -e 's/ bit.*//'`
bit=`echo "$gl_cv_cc_float_expbit0" | sed -e 's/word.*bit //'`
AC_DEFINE_UNQUOTED([FLT_EXPBIT0_WORD], [$word],
[Define as the word index where to find the exponent of 'float'.])
AC_DEFINE_UNQUOTED([FLT_EXPBIT0_BIT], [$bit],
[Define as the bit index in the word where to find bit 0 of the
exponent of 'float'.])
;;
esac
])
===============================================================================
*** lib/isnan.c 25 Mar 2007 19:45:26 -0000 1.5
--- lib/isnan.c 6 Apr 2007 20:17:50 -0000
***************
*** 36,42 ****
# endif
# define SIZE SIZEOF_LDBL
# define L_(literal) literal##L
! #else
# define FUNC rpl_isnan
# define DOUBLE double
# define MAX_EXP DBL_MAX_EXP
--- 36,42 ----
# endif
# define SIZE SIZEOF_LDBL
# define L_(literal) literal##L
! #elif ! defined USE_FLOAT
# define FUNC rpl_isnan
# define DOUBLE double
# define MAX_EXP DBL_MAX_EXP
***************
*** 48,53 ****
--- 48,65 ----
# endif
# define SIZE SIZEOF_DBL
# define L_(literal) literal
+ #else /* defined USE_FLOAT */
+ # define FUNC rpl_isnanf
+ # define DOUBLE float
+ # define MAX_EXP FLT_MAX_EXP
+ # define MIN_EXP FLT_MIN_EXP
+ # if defined FLT_EXPBIT0_WORD && defined FLT_EXPBIT0_BIT
+ # define KNOWN_EXPBIT0_LOCATION
+ # define EXPBIT0_WORD FLT_EXPBIT0_WORD
+ # define EXPBIT0_BIT FLT_EXPBIT0_BIT
+ # endif
+ # define SIZE SIZEOF_FLT
+ # define L_(literal) literal##f
#endif
#define EXP_MASK ((MAX_EXP - MIN_EXP) | 7)
