ldexpl.m4 3.77 KB
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# ldexpl.m4 serial 16
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dnl Copyright (C) 2007-2016 Free Software Foundation, Inc.
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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])
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  AC_REQUIRE([gl_LONG_DOUBLE_VS_DOUBLE])
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  AC_REQUIRE([gl_FUNC_ISNANL]) dnl for ISNANL_LIBM
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  dnl Persuade glibc <math.h> to declare ldexpl().
  AC_REQUIRE([gl_USE_SYSTEM_EXTENSIONS])

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  dnl Check whether it's declared.
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  dnl Mac OS X 10.3 has ldexpl() in libc but doesn't declare it in <math.h>.
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  AC_CHECK_DECL([ldexpl], , [HAVE_DECL_LDEXPL=0], [[#include <math.h>]])
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  LDEXPL_LIBM=
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  if test $HAVE_DECL_LDEXPL = 1; then
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    gl_CHECK_LDEXPL_NO_LIBM
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    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="$LIBS -lm"
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          AC_LINK_IFELSE(
            [AC_LANG_PROGRAM(
               [[#include <math.h>
                 long double x;]],
               [[return ldexpl (x, -1) > 0;]])],
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            [gl_cv_func_ldexpl_in_libm=yes],
            [gl_cv_func_ldexpl_in_libm=no])
          LIBS="$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 ;;
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        *)    gl_func_ldexpl=no; REPLACE_LDEXPL=1 ;;
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      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.])
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    fi
  fi
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  if test $HAVE_DECL_LDEXPL = 0 || test $gl_func_ldexpl = no; then
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    dnl Find libraries needed to link lib/ldexpl.c.
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    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
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  fi
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  AC_SUBST([LDEXPL_LIBM])
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])

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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],
    [
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      AC_LINK_IFELSE(
        [AC_LANG_PROGRAM(
           [[#include <math.h>
             long double x;]],
           [[return ldexpl (x, -1) > 0;]])],
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        [gl_cv_func_ldexpl_no_libm=yes],
        [gl_cv_func_ldexpl_no_libm=no])
    ])
])

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dnl Test whether ldexpl() works on finite numbers (this fails on AIX 5.1
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dnl and Mac OS X 10.4/PowerPC).
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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],
    [
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      AC_RUN_IFELSE(
        [AC_LANG_SOURCE([[
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#include <math.h>
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extern
#ifdef __cplusplus
"C"
#endif
long double ldexpl (long double, int);
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int main()
{
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  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;
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}]])],
        [gl_cv_func_ldexpl_works=yes],
        [gl_cv_func_ldexpl_works=no],
        [
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changequote(,)dnl
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         case "$host_os" in
           aix | aix[3-6]*) gl_cv_func_ldexpl_works="guessing no";;
           *)               gl_cv_func_ldexpl_works="guessing yes";;
         esac
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changequote([,])dnl
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        ])
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    ])
])