# ldexpl.m4 serial 17

dnl Copyright (C) 2007-2018 Free Software Foundation, Inc.

dnl This file is free software; the Free Software Foundation

dnl gives unlimited permission to copy and/or distribute it,

dnl with or without modifications, as long as this notice is preserved.

AC_DEFUN([gl_FUNC_LDEXPL],

[

  AC_REQUIRE([gl_MATH_H_DEFAULTS])

  AC_REQUIRE([gl_LONG_DOUBLE_VS_DOUBLE])

  AC_REQUIRE([gl_FUNC_ISNANL]) dnl for ISNANL_LIBM

  dnl Persuade glibc <math.h> to declare ldexpl().

  AC_REQUIRE([gl_USE_SYSTEM_EXTENSIONS])

  dnl Check whether it's declared.

  dnl Mac OS X 10.3 has ldexpl() in libc but doesn't declare it in <math.h>.

  AC_CHECK_DECL([ldexpl], , [HAVE_DECL_LDEXPL=0], [[#include <math.h>]])

  LDEXPL_LIBM=

  if test $HAVE_DECL_LDEXPL = 1; then

    gl_CHECK_LDEXPL_NO_LIBM

    if test $gl_cv_func_ldexpl_no_libm = no; then

      AC_CACHE_CHECK([whether ldexpl() can be used with libm],

        [gl_cv_func_ldexpl_in_libm],

        [

          save_LIBS="$LIBS"

          LIBS="$LIBS -lm"

          AC_LINK_IFELSE(

            [AC_LANG_PROGRAM(

               [[#include <math.h>

                 long double x;]],

               [[return ldexpl (x, -1) > 0;]])],

            [gl_cv_func_ldexpl_in_libm=yes],

            [gl_cv_func_ldexpl_in_libm=no])

          LIBS="$save_LIBS"

        ])

      if test $gl_cv_func_ldexpl_in_libm = yes; then

        LDEXPL_LIBM=-lm

      fi

    fi

    if test $gl_cv_func_ldexpl_no_libm = yes \

       || test $gl_cv_func_ldexpl_in_libm = yes; then

      save_LIBS="$LIBS"

      LIBS="$LIBS $LDEXPL_LIBM"

      gl_FUNC_LDEXPL_WORKS

      LIBS="$save_LIBS"

      case "$gl_cv_func_ldexpl_works" in

        *yes) gl_func_ldexpl=yes ;;

        *)    gl_func_ldexpl=no; REPLACE_LDEXPL=1 ;;

      esac

    else

      gl_func_ldexpl=no

    fi

    if test $gl_func_ldexpl = yes; then

      AC_DEFINE([HAVE_LDEXPL], [1],

        [Define if the ldexpl() function is available.])

    fi

  fi

  if test $HAVE_DECL_LDEXPL = 0 || test $gl_func_ldexpl = no; then

    dnl Find libraries needed to link lib/ldexpl.c.

    if test $HAVE_SAME_LONG_DOUBLE_AS_DOUBLE = 1; then

      AC_REQUIRE([gl_FUNC_LDEXP])

      LDEXPL_LIBM="$LDEXP_LIBM"

    else

      LDEXPL_LIBM="$ISNANL_LIBM"

    fi

  fi

  AC_SUBST([LDEXPL_LIBM])

])

dnl Test whether ldexpl() can be used without linking with libm.

dnl Set gl_cv_func_ldexpl_no_libm to 'yes' or 'no' accordingly.

AC_DEFUN([gl_CHECK_LDEXPL_NO_LIBM],

[

  AC_CACHE_CHECK([whether ldexpl() can be used without linking with libm],

    [gl_cv_func_ldexpl_no_libm],

    [

      AC_LINK_IFELSE(

        [AC_LANG_PROGRAM(

           [[#include <math.h>

             long double x;]],

           [[return ldexpl (x, -1) > 0;]])],

        [gl_cv_func_ldexpl_no_libm=yes],

        [gl_cv_func_ldexpl_no_libm=no])

    ])

])

dnl Test whether ldexpl() works on finite numbers (this fails on AIX 5.1

dnl and Mac OS X 10.4/PowerPC).

AC_DEFUN([gl_FUNC_LDEXPL_WORKS],

[

  AC_REQUIRE([AC_PROG_CC])

  AC_REQUIRE([AC_CANONICAL_HOST]) dnl for cross-compiles

  AC_CACHE_CHECK([whether ldexpl works], [gl_cv_func_ldexpl_works],

    [

      AC_RUN_IFELSE(

        [AC_LANG_SOURCE([[

#include <math.h>

extern

#ifdef __cplusplus

"C"

#endif

long double ldexpl (long double, int);

int main()

{

  int result = 0;

  {

    volatile long double x = 1.0;

    volatile long double y = ldexpl (x, -1);

    if (y != 0.5L)

      result |= 1;

  }

  {

    volatile long double x = 1.73205L;

    volatile long double y = ldexpl (x, 0);

    if (y != x)

      result |= 2;

  }

  return result;

}]])],

        [gl_cv_func_ldexpl_works=yes],

        [gl_cv_func_ldexpl_works=no],

        [

changequote(,)dnl

         case "$host_os" in

           aix | aix[3-6]*) gl_cv_func_ldexpl_works="guessing no" ;;

                            # Guess yes on native Windows.

           mingw*)          gl_cv_func_ldexpl_works="guessing yes" ;;

           *)               gl_cv_func_ldexpl_works="guessing yes" ;;

         esac

changequote([,])dnl

        ])

    ])

])