new module 'isnanf-nolibm'

[Bruno Haible]

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  <address@hidden>

        * 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 <address@hidden>, 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)