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 AC_DEFUN([gl_FUNC_FREXP],
9 AC_REQUIRE([gl_MATH_H_DEFAULTS])
10 AC_REQUIRE([gl_CHECK_FREXP_NO_LIBM])
12 if test $gl_cv_func_frexp_no_libm = no; then
13 AC_CACHE_CHECK([whether frexp() can be used with libm],
14 [gl_cv_func_frexp_in_libm],
22 [[int e; return frexp (x, &e) > 0;]])],
23 [gl_cv_func_frexp_in_libm=yes],
24 [gl_cv_func_frexp_in_libm=no])
27 if test $gl_cv_func_frexp_in_libm = yes; then
31 if test $gl_cv_func_frexp_no_libm = yes \
32 || test $gl_cv_func_frexp_in_libm = yes; then
34 LIBS="$LIBS $FREXP_LIBM"
37 case "$gl_cv_func_frexp_works" in
38 *yes) gl_func_frexp=yes ;;
39 *) gl_func_frexp=no; REPLACE_FREXP=1; FREXP_LIBM= ;;
44 if test $gl_func_frexp = yes; then
45 AC_DEFINE([HAVE_FREXP], [1],
46 [Define if the frexp() function is available and works.])
48 AC_SUBST([FREXP_LIBM])
51 AC_DEFUN([gl_FUNC_FREXP_NO_LIBM],
53 AC_REQUIRE([gl_MATH_H_DEFAULTS])
54 AC_REQUIRE([gl_CHECK_FREXP_NO_LIBM])
55 if test $gl_cv_func_frexp_no_libm = yes; then
57 case "$gl_cv_func_frexp_works" in
58 *yes) gl_func_frexp_no_libm=yes ;;
59 *) gl_func_frexp_no_libm=no; REPLACE_FREXP=1 ;;
62 gl_func_frexp_no_libm=no
63 dnl Set REPLACE_FREXP here because the system may have frexp in libm.
66 if test $gl_func_frexp_no_libm = yes; then
67 AC_DEFINE([HAVE_FREXP_IN_LIBC], [1],
68 [Define if the frexp() function is available in libc.])
72 dnl Test whether frexp() can be used without linking with libm.
73 dnl Set gl_cv_func_frexp_no_libm to 'yes' or 'no' accordingly.
74 AC_DEFUN([gl_CHECK_FREXP_NO_LIBM],
76 AC_CACHE_CHECK([whether frexp() can be used without linking with libm],
77 [gl_cv_func_frexp_no_libm],
83 [[int e; return frexp (x, &e) > 0;]])],
84 [gl_cv_func_frexp_no_libm=yes],
85 [gl_cv_func_frexp_no_libm=no])
89 dnl Test whether frexp() works also on denormalized numbers (this fails e.g. on
90 dnl NetBSD 3.0), on infinite numbers (this fails e.g. on IRIX 6.5 and mingw),
91 dnl and on negative zero (this fails e.g. on NetBSD 4.99).
92 AC_DEFUN([gl_FUNC_FREXP_WORKS],
94 AC_REQUIRE([AC_PROG_CC])
95 AC_REQUIRE([AC_CANONICAL_HOST]) dnl for cross-compiles
96 AC_CACHE_CHECK([whether frexp works], [gl_cv_func_frexp_works],
103 /* HP cc on HP-UX 10.20 has a bug with the constant expression -0.0.
104 ICC 10.0 has a bug when optimizing the expression -zero.
105 The expression -DBL_MIN * DBL_MIN does not work when cross-compiling
106 to PowerPC on MacOS X 10.5. */
107 #if defined __hpux || defined __sgi || defined __ICC
109 compute_minus_zero (void)
111 return -DBL_MIN * DBL_MIN;
113 # define minus_zero compute_minus_zero ()
115 double minus_zero = -0.0;
123 /* Test on denormalized numbers. */
124 for (i = 1, x = 1.0; i >= DBL_MIN_EXP; i--, x *= 0.5)
129 double y = frexp (x, &exp);
130 /* On machines with IEEE754 arithmetic: x = 1.11254e-308, exp = -1022.
131 On NetBSD: y = 0.75. Correct: y = 0.5. */
135 /* Test on infinite numbers. */
139 double y = frexp (x, &exp);
143 /* Test on negative zero. */
147 double y = frexp (x, &exp);
148 if (memcmp (&y, &x, sizeof x))
153 [gl_cv_func_frexp_works=yes],
154 [gl_cv_func_frexp_works=no],
156 netbsd* | irix* | mingw*) gl_cv_func_frexp_works="guessing no";;
157 *) gl_cv_func_frexp_works="guessing yes";;