m4/ldexp.m4

   1 # ldexp.m4 serial 1
   2 dnl Copyright (C) 2010-2014 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.
   6
   7 AC_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
  36 dnl Test whether ldexp() can be used without linking with libm.
  37 dnl Set gl_cv_func_ldexp_no_libm to 'yes' or 'no' accordingly.
  38 AC_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 ])