1# ldexpl.m4 serial 5
2dnl Copyright (C) 2007-2010 Free Software Foundation, Inc.
3dnl This file is free software; the Free Software Foundation
4dnl gives unlimited permission to copy and/or distribute it,
5dnl with or without modifications, as long as this notice is preserved.
6
7AC_DEFUN([gl_FUNC_LDEXPL],
8[
9  AC_REQUIRE([gl_MATH_H_DEFAULTS])
10  dnl Check whether it's declared.
11  dnl MacOS X 10.3 has ldexpl() in libc but doesn't declare it in <math.h>.
12  AC_CHECK_DECL([ldexpl], , [HAVE_DECL_LDEXPL=0], [#include <math.h>])
13  LDEXPL_LIBM=
14  if test $HAVE_DECL_LDEXPL = 1; then
15    AC_CACHE_CHECK([whether ldexpl() can be used without linking with libm],
16      [gl_cv_func_ldexpl_no_libm],
17      [
18        AC_TRY_LINK([#include <math.h>
19                     long double x;],
20                    [return ldexpl (x, -1) > 0;],
21          [gl_cv_func_ldexpl_no_libm=yes],
22          [gl_cv_func_ldexpl_no_libm=no])
23      ])
24    if test $gl_cv_func_ldexpl_no_libm = no; then
25      AC_CACHE_CHECK([whether ldexpl() can be used with libm],
26        [gl_cv_func_ldexpl_in_libm],
27        [
28          save_LIBS="$LIBS"
29          LIBS="$LIBS -lm"
30          AC_TRY_LINK([#include <math.h>
31                       long double x;],
32                      [return ldexpl (x, -1) > 0;],
33            [gl_cv_func_ldexpl_in_libm=yes],
34            [gl_cv_func_ldexpl_in_libm=no])
35          LIBS="$save_LIBS"
36        ])
37      if test $gl_cv_func_ldexpl_in_libm = yes; then
38        LDEXPL_LIBM=-lm
39      fi
40    fi
41    if test $gl_cv_func_ldexpl_no_libm = yes \
42       || test $gl_cv_func_ldexpl_in_libm = yes; then
43      save_LIBS="$LIBS"
44      LIBS="$LIBS $LDEXPL_LIBM"
45      gl_FUNC_LDEXPL_WORKS
46      LIBS="$save_LIBS"
47      case "$gl_cv_func_ldexpl_works" in
48        *yes) gl_func_ldexpl=yes ;;
49        *)    gl_func_ldexpl=no; REPLACE_LDEXPL=1; LDEXPL_LIBM= ;;
50      esac
51    else
52      gl_func_ldexpl=no
53    fi
54    if test $gl_func_ldexpl = yes; then
55      AC_DEFINE([HAVE_LDEXPL], [1],
56        [Define if the ldexpl() function is available.])
57    fi
58  fi
59  if test $HAVE_DECL_LDEXPL = 0 || test $gl_func_ldexpl = no; then
60    AC_LIBOBJ([ldexpl])
61  fi
62  AC_SUBST([LDEXPL_LIBM])
63])
64
65dnl Test whether ldexpl() works on finite numbers (this fails on AIX 5.1
66dnl and MacOS X 10.4/PowerPC).
67AC_DEFUN([gl_FUNC_LDEXPL_WORKS],
68[
69  AC_REQUIRE([AC_PROG_CC])
70  AC_REQUIRE([AC_CANONICAL_HOST]) dnl for cross-compiles
71  AC_CACHE_CHECK([whether ldexpl works], [gl_cv_func_ldexpl_works],
72    [
73      AC_TRY_RUN([
74#include <math.h>
75extern long double ldexpl (long double, int);
76int main()
77{
78  volatile long double x1 = 1.0;
79  volatile long double y1 = ldexpl (x1, -1);
80  volatile long double x2 = 1.73205L;
81  volatile long double y2 = ldexpl (x2, 0);
82  return (y1 != 0.5L) || (y2 != x2);
83}], [gl_cv_func_ldexpl_works=yes], [gl_cv_func_ldexpl_works=no],
84      [case "$host_os" in
85         aix*) gl_cv_func_ldexpl_works="guessing no";;
86         *)    gl_cv_func_ldexpl_works="guessing yes";;
87       esac
88      ])
89    ])
90])
91