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],
111 /* HP cc on HP-UX 10.20 has a bug with the constant expression -0.0.
112 So we use -zero instead. */
114 /* Test on denormalized numbers. */
115 for (i = 1, x = 1.0; i >= DBL_MIN_EXP; i--, x *= 0.5)
120 double y = frexp (x, &exp);
121 /* On machines with IEEE754 arithmetic: x = 1.11254e-308, exp = -1022.
122 On NetBSD: y = 0.75. Correct: y = 0.5. */
126 /* Test on infinite numbers. */
130 double y = frexp (x, &exp);
134 /* Test on negative zero. */
138 double y = frexp (x, &exp);
139 if (memcmp (&y, &x, sizeof x))
144 [gl_cv_func_frexp_works=yes],
145 [gl_cv_func_frexp_works=no],
147 netbsd* | irix* | mingw*) gl_cv_func_frexp_works="guessing no";;
148 *) gl_cv_func_frexp_works="guessing yes";;