# frexpl.m4 serial 5
dnl Copyright (C) 2007 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_FREXPL],
[
  AC_REQUIRE([gl_MATH_H_DEFAULTS])
  FREXPL_LIBM=
  AC_CACHE_CHECK([whether frexpl() can be used without linking with libm],
    [gl_cv_func_frexpl_no_libm],
    [
      AC_TRY_LINK([#include <math.h>
                   long double x;],
                  [int e; return frexpl (x, &e) > 0;],
        [gl_cv_func_frexpl_no_libm=yes],
        [gl_cv_func_frexpl_no_libm=no])
    ])
  if test $gl_cv_func_frexpl_no_libm = no; then
    AC_CACHE_CHECK([whether frexpl() can be used with libm],
      [gl_cv_func_frexpl_in_libm],
      [
        save_LIBS="$LIBS"
        LIBS="$LIBS -lm"
        AC_TRY_LINK([#include <math.h>
                     long double x;],
                    [int e; return frexpl (x, &e) > 0;],
          [gl_cv_func_frexpl_in_libm=yes],
          [gl_cv_func_frexpl_in_libm=no])
        LIBS="$save_LIBS"
      ])
    if test $gl_cv_func_frexpl_in_libm = yes; then
      FREXPL_LIBM=-lm
    fi
  fi
  if test $gl_cv_func_frexpl_no_libm = yes \
     || test $gl_cv_func_frexpl_in_libm = yes; then
    save_LIBS="$LIBS"
    LIBS="$LIBS $FREXPL_LIBM"
    gl_FUNC_FREXPL_WORKS
    LIBS="$save_LIBS"
    case "$gl_cv_func_frexpl_works" in
      *yes) gl_func_frexpl=yes ;;
      *)    gl_func_frexpl=no; REPLACE_FREXPL=1; FREXPL_LIBM= ;;
    esac
  else
    gl_func_frexpl=no
  fi
  if test $gl_func_frexpl = yes; then
    AC_DEFINE([HAVE_FREXPL], 1,
      [Define if the frexpl() function is available.])
    dnl Also check whether it's declared.
    dnl MacOS X 10.3 has frexpl() in libc but doesn't declare it in <math.h>.
    AC_CHECK_DECL([frexpl], , [HAVE_DECL_FREXPL=0], [#include <math.h>])
  else
    HAVE_DECL_FREXPL=0
    AC_LIBOBJ([frexpl])
  fi
  AC_SUBST([FREXPL_LIBM])
])

AC_DEFUN([gl_FUNC_FREXPL_NO_LIBM],
[
  AC_REQUIRE([gl_MATH_H_DEFAULTS])
  AC_CACHE_CHECK([whether frexpl() can be used without linking with libm],
    [gl_cv_func_frexpl_no_libm],
    [
      AC_TRY_LINK([#include <math.h>
                   long double x;],
                  [int e; return frexpl (x, &e) > 0;],
        [gl_cv_func_frexpl_no_libm=yes],
        [gl_cv_func_frexpl_no_libm=no])
    ])
  if test $gl_cv_func_frexpl_no_libm = yes; then
    gl_FUNC_FREXPL_WORKS
    case "$gl_cv_func_frexpl_works" in
      *yes) gl_func_frexpl_no_libm=yes ;;
      *)    gl_func_frexpl_no_libm=no; REPLACE_FREXPL=1 ;;
    esac
  else
    gl_func_frexpl_no_libm=no
    dnl Set REPLACE_FREXPL here because the system may have frexpl in libm.
    REPLACE_FREXPL=1
  fi
  if test $gl_func_frexpl_no_libm = yes; then
    AC_DEFINE([HAVE_FREXPL_IN_LIBC], 1,
      [Define if the frexpl() function is available in libc.])
    dnl Also check whether it's declared.
    dnl MacOS X 10.3 has frexpl() in libc but doesn't declare it in <math.h>.
    AC_CHECK_DECL([frexpl], , [HAVE_DECL_FREXPL=0], [#include <math.h>])
  else
    HAVE_DECL_FREXPL=0
    AC_LIBOBJ([frexpl])
  fi
])

dnl Test whether frexpl() works on finite numbers (this fails on AIX 5.1 and
dnl on BeOS) and also on infinite numbers (this fails e.g. on IRIX 6.5 and
dnl mingw).
AC_DEFUN([gl_FUNC_FREXPL_WORKS],
[
  AC_REQUIRE([AC_PROG_CC])
  AC_REQUIRE([AC_CANONICAL_HOST]) dnl for cross-compiles
  AC_CACHE_CHECK([whether frexpl works], [gl_cv_func_frexpl_works],
    [
      AC_TRY_RUN([
#include <math.h>
extern long double frexpl (long double, int *);
int main()
{
  volatile long double x;
  /* Test on finite numbers.  */
  x = 16.0L;
  {
    int exp = -9999;
    frexpl (x, &exp);
    if (exp != 5)
      return 1;
  }
  /* Test on large finite numbers.  This fails on BeOS at i = 16322, while
     LDBL_MAX_EXP = 16384.
     In the loop end test, we test x against Infinity, rather than comparing
     i with LDBL_MAX_EXP, because BeOS <float.h> has a wrong LDBL_MAX_EXP.  */
  {
    int i;
    for (i = 1, x = 1.0L; x != x + x; i++, x *= 2.0L)
      {
        int exp = -9999;
        frexpl (x, &exp);
        if (exp != i)
          return 1;
      }
  }
  /* Test on infinite numbers.  */
  x = 1.0L / 0.0L;
  {
    int exp;
    long double y = frexpl (x, &exp);
    if (y != x)
      return 1;
  }
  return 0;
}], [gl_cv_func_frexpl_works=yes], [gl_cv_func_frexpl_works=no],
      [case "$host_os" in
         aix* | beos* | irix* | mingw* | pw*)
            gl_cv_func_frexpl_works="guessing no";;
         *) gl_cv_func_frexpl_works="guessing yes";;
       esac
      ])
    ])
])