2 dnl Copyright (C) 2007-2011 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 dnl The variable gl_func_isnanf set here is used by isnan.m4.
21 if test $gl_cv_func_isnanf_no_libm = yes \
22 || test $gl_cv_func_isnanf_in_libm = yes; then
24 LIBS="$LIBS $ISNANF_LIBM"
27 case "$gl_cv_func_isnanf_works" in
28 *yes) gl_func_isnanf=yes ;;
29 *) gl_func_isnanf=no; ISNANF_LIBM= ;;
34 if test $gl_func_isnanf != yes; then
39 AC_SUBST([ISNANF_LIBM])
42 dnl Check how to get or define isnanf() without linking with libm.
44 AC_DEFUN([gl_FUNC_ISNANF_NO_LIBM],
46 gl_HAVE_ISNANF_NO_LIBM
47 if test $gl_cv_func_isnanf_no_libm = yes; then
50 if test $gl_cv_func_isnanf_no_libm = yes \
51 && { case "$gl_cv_func_isnanf_works" in
56 AC_DEFINE([HAVE_ISNANF_IN_LIBC], [1],
57 [Define if the isnan(float) function is available in libc.])
64 dnl Prerequisites of replacement isnanf definition. It does not need -lm.
65 AC_DEFUN([gl_PREREQ_ISNANF],
67 gl_FLOAT_EXPONENT_LOCATION
70 dnl Test whether isnanf() can be used without libm.
71 AC_DEFUN([gl_HAVE_ISNANF_NO_LIBM],
73 AC_CACHE_CHECK([whether isnan(float) can be used without linking with libm],
74 [gl_cv_func_isnanf_no_libm],
81 # define isnanf(x) __builtin_isnanf ((float)(x))
84 # define isnanf(x) isnan ((float)(x))
87 [[return isnanf (x);]])],
88 [gl_cv_func_isnanf_no_libm=yes],
89 [gl_cv_func_isnanf_no_libm=no])
93 dnl Test whether isnanf() can be used with libm.
94 AC_DEFUN([gl_HAVE_ISNANF_IN_LIBM],
96 AC_CACHE_CHECK([whether isnan(float) can be used with libm],
97 [gl_cv_func_isnanf_in_libm],
106 # define isnanf(x) __builtin_isnanf ((float)(x))
109 # define isnanf(x) isnan ((float)(x))
112 [[return isnanf (x);]])],
113 [gl_cv_func_isnanf_in_libm=yes],
114 [gl_cv_func_isnanf_in_libm=no])
119 dnl Test whether isnanf() rejects Infinity (this fails on Solaris 2.5.1),
120 dnl recognizes a NaN (this fails on IRIX 6.5 with cc), and recognizes a NaN
121 dnl with in-memory representation 0x7fbfffff (this fails on IRIX 6.5).
122 AC_DEFUN([gl_ISNANF_WORKS],
124 AC_REQUIRE([AC_PROG_CC])
125 AC_REQUIRE([AC_CANONICAL_HOST]) dnl for cross-compiles
126 AC_REQUIRE([gl_FLOAT_EXPONENT_LOCATION])
127 AC_CACHE_CHECK([whether isnan(float) works], [gl_cv_func_isnanf_works],
134 # define isnanf(x) __builtin_isnanf ((float)(x))
137 # define isnanf(x) isnan ((float)(x))
139 /* The Compaq (ex-DEC) C 6.4 compiler chokes on the expression 0.0 / 0.0. */
144 static float zero = 0.0f;
148 # define NaN() (0.0f / 0.0f)
151 ((sizeof (float) + sizeof (unsigned int) - 1) / sizeof (unsigned int))
152 typedef union { unsigned int word[NWORDS]; float value; } memory_float;
157 if (isnanf (1.0f / 0.0f))
160 if (!isnanf (NaN ()))
163 #if defined FLT_EXPBIT0_WORD && defined FLT_EXPBIT0_BIT
164 /* The isnanf function should be immune against changes in the sign bit and
165 in the mantissa bits. The xor operation twiddles a bit that can only be
166 a sign bit or a mantissa bit. */
167 if (FLT_EXPBIT0_WORD == 0 && FLT_EXPBIT0_BIT > 0)
172 /* Set the bits below the exponent to 01111...111. */
173 m.word[0] &= -1U << FLT_EXPBIT0_BIT;
174 m.word[0] |= 1U << (FLT_EXPBIT0_BIT - 1) - 1;
175 if (!isnanf (m.value))
182 [gl_cv_func_isnanf_works=yes],
183 [gl_cv_func_isnanf_works=no],
185 irix* | solaris*) gl_cv_func_isnanf_works="guessing no";;
186 *) gl_cv_func_isnanf_works="guessing yes";;