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 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.])
50 AC_SUBST([FREXP_LIBM])
53 AC_DEFUN([gl_FUNC_FREXP_NO_LIBM],
55 AC_REQUIRE([gl_MATH_H_DEFAULTS])
56 AC_REQUIRE([gl_CHECK_FREXP_NO_LIBM])
57 if test $gl_cv_func_frexp_no_libm = yes; then
59 case "$gl_cv_func_frexp_works" in
60 *yes) gl_func_frexp_no_libm=yes ;;
61 *) gl_func_frexp_no_libm=no; REPLACE_FREXP=1 ;;
64 gl_func_frexp_no_libm=no
65 dnl Set REPLACE_FREXP here because the system may have frexp in libm.
68 if test $gl_func_frexp_no_libm = yes; then
69 AC_DEFINE([HAVE_FREXP_IN_LIBC], [1],
70 [Define if the frexp() function is available in libc.])
76 dnl Test whether frexp() can be used without linking with libm.
77 dnl Set gl_cv_func_frexp_no_libm to 'yes' or 'no' accordingly.
78 AC_DEFUN([gl_CHECK_FREXP_NO_LIBM],
80 AC_CACHE_CHECK([whether frexp() can be used without linking with libm],
81 [gl_cv_func_frexp_no_libm],
87 [[int e; return frexp (x, &e) > 0;]])],
88 [gl_cv_func_frexp_no_libm=yes],
89 [gl_cv_func_frexp_no_libm=no])
93 dnl Test whether frexp() works also on denormalized numbers (this fails e.g. on
94 dnl NetBSD 3.0), on infinite numbers (this fails e.g. on IRIX 6.5 and mingw),
95 dnl and on negative zero (this fails e.g. on NetBSD 4.99).
96 AC_DEFUN([gl_FUNC_FREXP_WORKS],
98 AC_REQUIRE([AC_PROG_CC])
99 AC_REQUIRE([AC_CANONICAL_HOST]) dnl for cross-compiles
100 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 ICC 10.0 has a bug when optimizing the expression -zero.
109 The expression -DBL_MIN * DBL_MIN does not work when cross-compiling
110 to PowerPC on MacOS X 10.5. */
111 #if defined __hpux || defined __sgi || defined __ICC
113 compute_minus_zero (void)
115 return -DBL_MIN * DBL_MIN;
117 # define minus_zero compute_minus_zero ()
119 double minus_zero = -0.0;
126 /* Test on denormalized numbers. */
127 for (i = 1, x = 1.0; i >= DBL_MIN_EXP; i--, x *= 0.5)
132 double y = frexp (x, &exp);
133 /* On machines with IEEE754 arithmetic: x = 1.11254e-308, exp = -1022.
134 On NetBSD: y = 0.75. Correct: y = 0.5. */
138 /* Test on infinite numbers. */
142 double y = frexp (x, &exp);
146 /* Test on negative zero. */
150 double y = frexp (x, &exp);
151 if (memcmp (&y, &x, sizeof x))
156 [gl_cv_func_frexp_works=yes],
157 [gl_cv_func_frexp_works=no],
159 netbsd* | irix* | mingw*) gl_cv_func_frexp_works="guessing no";;
160 *) gl_cv_func_frexp_works="guessing yes";;