2 dnl Copyright (C) 2007 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 dnl Test whether frexp() works also on denormalized numbers (this fails e.g. on
60 dnl NetBSD 3.0) and on infinite numbers (this fails e.g. on IRIX 6.5).
61 AC_DEFUN([gl_FUNC_FREXP_WORKS],
63 AC_REQUIRE([AC_PROG_CC])
64 AC_REQUIRE([AC_CANONICAL_HOST]) dnl for cross-compiles
65 AC_CACHE_CHECK([whether frexp works], [gl_cv_func_frexp_works],
74 /* Test on denormalized numbers. */
75 for (i = 1, x = 1.0; i >= DBL_MIN_EXP; i--, x *= 0.5)
80 double y = frexp (x, &exp);
81 /* On machines with IEEE754 arithmetic: x = 1.11254e-308, exp = -1022.
82 On NetBSD: y = 0.75. Correct: y = 0.5. */
86 /* Test on infinite numbers. */
90 double y = frexp (x, &exp);
95 }], [gl_cv_func_frexp_works=yes], [gl_cv_func_frexp_works=no],
97 netbsd* | irix*) gl_cv_func_frexp_works="guessing no";;
98 *) gl_cv_func_frexp_works="guessing yes";;