2 dnl Copyright (C) 2007, 2008, 2009 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 AC_DEFUN([gl_FUNC_FREXP],
9 AC_REQUIRE([gl_MATH_H_DEFAULTS])
11 AC_CACHE_CHECK([whether frexp() can be used without linking with libm],
12 [gl_cv_func_frexp_no_libm],
14 AC_TRY_LINK([#include <math.h>
16 [int e; return frexp (x, &e) > 0;],
17 [gl_cv_func_frexp_no_libm=yes],
18 [gl_cv_func_frexp_no_libm=no])
20 if test $gl_cv_func_frexp_no_libm = no; then
21 AC_CACHE_CHECK([whether frexp() can be used with libm],
22 [gl_cv_func_frexp_in_libm],
26 AC_TRY_LINK([#include <math.h>
28 [int e; return frexp (x, &e) > 0;],
29 [gl_cv_func_frexp_in_libm=yes],
30 [gl_cv_func_frexp_in_libm=no])
33 if test $gl_cv_func_frexp_in_libm = yes; then
37 if test $gl_cv_func_frexp_no_libm = yes \
38 || test $gl_cv_func_frexp_in_libm = yes; then
40 LIBS="$LIBS $FREXP_LIBM"
43 case "$gl_cv_func_frexp_works" in
44 *yes) gl_func_frexp=yes ;;
45 *) gl_func_frexp=no; REPLACE_FREXP=1; FREXP_LIBM= ;;
50 if test $gl_func_frexp = yes; then
51 AC_DEFINE([HAVE_FREXP], [1],
52 [Define if the frexp() function is available and works.])
56 AC_SUBST([FREXP_LIBM])
59 AC_DEFUN([gl_FUNC_FREXP_NO_LIBM],
61 AC_REQUIRE([gl_MATH_H_DEFAULTS])
62 AC_CACHE_CHECK([whether frexp() can be used without linking with libm],
63 [gl_cv_func_frexp_no_libm],
65 AC_TRY_LINK([#include <math.h>
67 [int e; return frexp (x, &e) > 0;],
68 [gl_cv_func_frexp_no_libm=yes],
69 [gl_cv_func_frexp_no_libm=no])
71 if test $gl_cv_func_frexp_no_libm = yes; then
73 case "$gl_cv_func_frexp_works" in
74 *yes) gl_func_frexp_no_libm=yes ;;
75 *) gl_func_frexp_no_libm=no; REPLACE_FREXP=1 ;;
78 gl_func_frexp_no_libm=no
79 dnl Set REPLACE_FREXP here because the system may have frexp in libm.
82 if test $gl_func_frexp_no_libm = yes; then
83 AC_DEFINE([HAVE_FREXP_IN_LIBC], [1],
84 [Define if the frexp() function is available in libc.])
90 dnl Test whether frexp() works also on denormalized numbers (this fails e.g. on
91 dnl NetBSD 3.0), on infinite numbers (this fails e.g. on IRIX 6.5 and mingw),
92 dnl and on negative zero (this fails e.g. on NetBSD 4.99).
93 AC_DEFUN([gl_FUNC_FREXP_WORKS],
95 AC_REQUIRE([AC_PROG_CC])
96 AC_REQUIRE([AC_CANONICAL_HOST]) dnl for cross-compiles
97 AC_CACHE_CHECK([whether frexp works], [gl_cv_func_frexp_works],
107 /* HP cc on HP-UX 10.20 has a bug with the constant expression -0.0.
108 So we use -zero instead. */
110 /* Test on denormalized numbers. */
111 for (i = 1, x = 1.0; i >= DBL_MIN_EXP; i--, x *= 0.5)
116 double y = frexp (x, &exp);
117 /* On machines with IEEE754 arithmetic: x = 1.11254e-308, exp = -1022.
118 On NetBSD: y = 0.75. Correct: y = 0.5. */
122 /* Test on infinite numbers. */
126 double y = frexp (x, &exp);
130 /* Test on negative zero. */
134 double y = frexp (x, &exp);
135 if (memcmp (&y, &x, sizeof x))
139 }], [gl_cv_func_frexp_works=yes], [gl_cv_func_frexp_works=no],
141 netbsd* | irix* | mingw*) gl_cv_func_frexp_works="guessing no";;
142 *) gl_cv_func_frexp_works="guessing yes";;