1# ldexp.m4 serial 1
2dnl Copyright (C) 2010-2020 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_LDEXP],
8[
9  AC_REQUIRE([gl_CHECK_LDEXP_NO_LIBM])
10  LDEXP_LIBM=
11  if test $gl_cv_func_ldexp_no_libm = no; then
12    AC_CACHE_CHECK([whether ldexp() can be used with libm],
13      [gl_cv_func_ldexp_in_libm],
14      [
15        save_LIBS="$LIBS"
16        LIBS="$LIBS -lm"
17        AC_LINK_IFELSE(
18          [AC_LANG_PROGRAM([[#ifndef __NO_MATH_INLINES
19                             # define __NO_MATH_INLINES 1 /* for glibc */
20                             #endif
21                             #include <math.h>
22                             double (*funcptr) (double, int) = ldexp;
23                             double x;]],
24                           [[return ldexp (x, -1) > 0;]])],
25          [gl_cv_func_ldexp_in_libm=yes],
26          [gl_cv_func_ldexp_in_libm=no])
27        LIBS="$save_LIBS"
28      ])
29    if test $gl_cv_func_ldexp_in_libm = yes; then
30      LDEXP_LIBM=-lm
31    fi
32  fi
33  AC_SUBST([LDEXP_LIBM])
34])
35
36dnl Test whether ldexp() can be used without linking with libm.
37dnl Set gl_cv_func_ldexp_no_libm to 'yes' or 'no' accordingly.
38AC_DEFUN([gl_CHECK_LDEXP_NO_LIBM],
39[
40  AC_CACHE_CHECK([whether ldexp() can be used without linking with libm],
41    [gl_cv_func_ldexp_no_libm],
42    [
43      AC_LINK_IFELSE(
44        [AC_LANG_PROGRAM([[#ifndef __NO_MATH_INLINES
45                           # define __NO_MATH_INLINES 1 /* for glibc */
46                           #endif
47                           #include <math.h>
48                           double (*funcptr) (double, int) = ldexp;
49                           double x;]],
50                         [[return ldexp (x, -1) > 0;]])],
51        [gl_cv_func_ldexp_no_libm=yes],
52        [gl_cv_func_ldexp_no_libm=no])
53    ])
54])
55