2 dnl Copyright (C) 2007-2010 Free Software Foundation, Inc.
3 dnl This file is free software; the Free Software Foundation
4 dnl gives unlimited permission to copy and/or distribute it,
5 dnl with or without modifications, as long as this notice is preserved.
7 dnl Check how to get or define isnanf().
9 AC_DEFUN([gl_FUNC_ISNANF],
11 AC_REQUIRE([gl_MATH_H_DEFAULTS])
13 gl_HAVE_ISNANF_NO_LIBM
14 if test $gl_cv_func_isnanf_no_libm = no; then
15 gl_HAVE_ISNANF_IN_LIBM
16 if test $gl_cv_func_isnanf_in_libm = yes; then
20 if test $gl_cv_func_isnanf_no_libm = yes \
21 || test $gl_cv_func_isnanf_in_libm = yes; then
23 LIBS="$LIBS $ISNANF_LIBM"
26 case "$gl_cv_func_isnanf_works" in
27 *yes) gl_func_isnanf=yes ;;
28 *) gl_func_isnanf=no; ISNANF_LIBM= ;;
33 if test $gl_func_isnanf != yes; then
37 AC_SUBST([ISNANF_LIBM])
40 dnl Check how to get or define isnanf() without linking with libm.
42 AC_DEFUN([gl_FUNC_ISNANF_NO_LIBM],
44 gl_HAVE_ISNANF_NO_LIBM
45 if test $gl_cv_func_isnanf_no_libm = yes; then
48 if test $gl_cv_func_isnanf_no_libm = yes \
49 && { case "$gl_cv_func_isnanf_works" in
54 AC_DEFINE([HAVE_ISNANF_IN_LIBC], [1],
55 [Define if the isnan(float) function is available in libc.])
61 dnl Pull in replacement isnanf definition. It does not need -lm.
62 AC_DEFUN([gl_BUILD_ISNANF],
65 gl_FLOAT_EXPONENT_LOCATION
68 dnl Test whether isnanf() can be used without libm.
69 AC_DEFUN([gl_HAVE_ISNANF_NO_LIBM],
71 AC_CACHE_CHECK([whether isnan(float) can be used without linking with libm],
72 [gl_cv_func_isnanf_no_libm],
74 AC_TRY_LINK([#include <math.h>
77 # define isnanf(x) __builtin_isnanf ((float)(x))
80 # define isnanf(x) isnan ((float)(x))
84 [gl_cv_func_isnanf_no_libm=yes],
85 [gl_cv_func_isnanf_no_libm=no])
89 dnl Test whether isnanf() can be used with libm.
90 AC_DEFUN([gl_HAVE_ISNANF_IN_LIBM],
92 AC_CACHE_CHECK([whether isnan(float) can be used with libm],
93 [gl_cv_func_isnanf_in_libm],
97 AC_TRY_LINK([#include <math.h>
100 # define isnanf(x) __builtin_isnanf ((float)(x))
103 # define isnanf(x) isnan ((float)(x))
106 [return isnanf (x);],
107 [gl_cv_func_isnanf_in_libm=yes],
108 [gl_cv_func_isnanf_in_libm=no])
113 dnl Test whether isnanf() rejects Infinity (this fails on Solaris 2.5.1),
114 dnl recognizes a NaN (this fails on IRIX 6.5 with cc), and recognizes a NaN
115 dnl with in-memory representation 0x7fbfffff (this fails on IRIX 6.5).
116 AC_DEFUN([gl_ISNANF_WORKS],
118 AC_REQUIRE([AC_PROG_CC])
119 AC_REQUIRE([AC_CANONICAL_HOST]) dnl for cross-compiles
120 AC_REQUIRE([gl_FLOAT_EXPONENT_LOCATION])
121 AC_CACHE_CHECK([whether isnan(float) works], [gl_cv_func_isnanf_works],
127 # define isnanf(x) __builtin_isnanf ((float)(x))
130 # define isnanf(x) isnan ((float)(x))
132 /* The Compaq (ex-DEC) C 6.4 compiler chokes on the expression 0.0 / 0.0. */
137 static float zero = 0.0f;
141 # define NaN() (0.0f / 0.0f)
144 ((sizeof (float) + sizeof (unsigned int) - 1) / sizeof (unsigned int))
145 typedef union { unsigned int word[NWORDS]; float value; } memory_float;
150 if (isnanf (1.0f / 0.0f))
153 if (!isnanf (NaN ()))
156 #if defined FLT_EXPBIT0_WORD && defined FLT_EXPBIT0_BIT
157 /* The isnanf function should be immune against changes in the sign bit and
158 in the mantissa bits. The xor operation twiddles a bit that can only be
159 a sign bit or a mantissa bit. */
160 if (FLT_EXPBIT0_WORD == 0 && FLT_EXPBIT0_BIT > 0)
163 /* Set the bits below the exponent to 01111...111. */
164 m.word[0] &= -1U << FLT_EXPBIT0_BIT;
165 m.word[0] |= 1U << (FLT_EXPBIT0_BIT - 1) - 1;
166 if (!isnanf (m.value))
172 }], [gl_cv_func_isnanf_works=yes], [gl_cv_func_isnanf_works=no],
174 irix* | solaris*) gl_cv_func_isnanf_works="guessing no";;
175 *) gl_cv_func_isnanf_works="guessing yes";;