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# frexp.m4 serial 10
dnl Copyright (C) 2007-2011 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_FREXP],
[
AC_REQUIRE([gl_MATH_H_DEFAULTS])
AC_REQUIRE([gl_CHECK_FREXP_NO_LIBM])
FREXP_LIBM=
if test $gl_cv_func_frexp_no_libm = no; then
AC_CACHE_CHECK([whether frexp() can be used with libm],
[gl_cv_func_frexp_in_libm],
[
save_LIBS="$LIBS"
LIBS="$LIBS -lm"
AC_LINK_IFELSE(
[AC_LANG_PROGRAM(
[[#include <math.h>
double x;]],
[[int e; return frexp (x, &e) > 0;]])],
[gl_cv_func_frexp_in_libm=yes],
[gl_cv_func_frexp_in_libm=no])
LIBS="$save_LIBS"
])
if test $gl_cv_func_frexp_in_libm = yes; then
FREXP_LIBM=-lm
fi
fi
if test $gl_cv_func_frexp_no_libm = yes \
|| test $gl_cv_func_frexp_in_libm = yes; then
save_LIBS="$LIBS"
LIBS="$LIBS $FREXP_LIBM"
gl_FUNC_FREXP_WORKS
LIBS="$save_LIBS"
case "$gl_cv_func_frexp_works" in
*yes) gl_func_frexp=yes ;;
*) gl_func_frexp=no; REPLACE_FREXP=1; FREXP_LIBM= ;;
esac
else
gl_func_frexp=no
fi
if test $gl_func_frexp = yes; then
AC_DEFINE([HAVE_FREXP], [1],
[Define if the frexp() function is available and works.])
else
AC_LIBOBJ([frexp])
fi
AC_SUBST([FREXP_LIBM])
])
AC_DEFUN([gl_FUNC_FREXP_NO_LIBM],
[
AC_REQUIRE([gl_MATH_H_DEFAULTS])
AC_REQUIRE([gl_CHECK_FREXP_NO_LIBM])
if test $gl_cv_func_frexp_no_libm = yes; then
gl_FUNC_FREXP_WORKS
case "$gl_cv_func_frexp_works" in
*yes) gl_func_frexp_no_libm=yes ;;
*) gl_func_frexp_no_libm=no; REPLACE_FREXP=1 ;;
esac
else
gl_func_frexp_no_libm=no
dnl Set REPLACE_FREXP here because the system may have frexp in libm.
REPLACE_FREXP=1
fi
if test $gl_func_frexp_no_libm = yes; then
AC_DEFINE([HAVE_FREXP_IN_LIBC], [1],
[Define if the frexp() function is available in libc.])
else
AC_LIBOBJ([frexp])
fi
])
dnl Test whether frexp() can be used without linking with libm.
dnl Set gl_cv_func_frexp_no_libm to 'yes' or 'no' accordingly.
AC_DEFUN([gl_CHECK_FREXP_NO_LIBM],
[
AC_CACHE_CHECK([whether frexp() can be used without linking with libm],
[gl_cv_func_frexp_no_libm],
[
AC_LINK_IFELSE(
[AC_LANG_PROGRAM(
[[#include <math.h>
double x;]],
[[int e; return frexp (x, &e) > 0;]])],
[gl_cv_func_frexp_no_libm=yes],
[gl_cv_func_frexp_no_libm=no])
])
])
dnl Test whether frexp() works also on denormalized numbers (this fails e.g. on
dnl NetBSD 3.0), on infinite numbers (this fails e.g. on IRIX 6.5 and mingw),
dnl and on negative zero (this fails e.g. on NetBSD 4.99).
AC_DEFUN([gl_FUNC_FREXP_WORKS],
[
AC_REQUIRE([AC_PROG_CC])
AC_REQUIRE([AC_CANONICAL_HOST]) dnl for cross-compiles
AC_CACHE_CHECK([whether frexp works], [gl_cv_func_frexp_works],
[
AC_RUN_IFELSE(
[AC_LANG_SOURCE([[
#include <float.h>
#include <math.h>
#include <string.h>
/* HP cc on HP-UX 10.20 has a bug with the constant expression -0.0.
ICC 10.0 has a bug when optimizing the expression -zero.
The expression -DBL_MIN * DBL_MIN does not work when cross-compiling
to PowerPC on MacOS X 10.5. */
#if defined __hpux || defined __sgi || defined __ICC
static double
compute_minus_zero (void)
{
return -DBL_MIN * DBL_MIN;
}
# define minus_zero compute_minus_zero ()
#else
double minus_zero = -0.0;
#endif
int main()
{
int result = 0;
int i;
volatile double x;
double zero = 0.0;
/* Test on denormalized numbers. */
for (i = 1, x = 1.0; i >= DBL_MIN_EXP; i--, x *= 0.5)
;
if (x > 0.0)
{
int exp;
double y = frexp (x, &exp);
/* On machines with IEEE754 arithmetic: x = 1.11254e-308, exp = -1022.
On NetBSD: y = 0.75. Correct: y = 0.5. */
if (y != 0.5)
result |= 1;
}
/* Test on infinite numbers. */
x = 1.0 / 0.0;
{
int exp;
double y = frexp (x, &exp);
if (y != x)
result |= 2;
}
/* Test on negative zero. */
x = minus_zero;
{
int exp;
double y = frexp (x, &exp);
if (memcmp (&y, &x, sizeof x))
result |= 4;
}
return result;
}]])],
[gl_cv_func_frexp_works=yes],
[gl_cv_func_frexp_works=no],
[case "$host_os" in
netbsd* | irix* | mingw*) gl_cv_func_frexp_works="guessing no";;
*) gl_cv_func_frexp_works="guessing yes";;
esac
])
])
])
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