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# modf.m4 serial 10
dnl Copyright (C) 2011-2023 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_MODF],
[
m4_divert_text([DEFAULTS], [gl_modf_required=plain])
AC_REQUIRE([gl_MATH_H_DEFAULTS])
dnl Determine MODF_LIBM.
gl_MATHFUNC([modf], [double], [(double, double *)])
m4_ifdef([gl_FUNC_MODF_IEEE], [
if test $gl_modf_required = ieee && test $REPLACE_MODF = 0; then
AC_REQUIRE([AC_CANONICAL_HOST]) dnl for cross-compiles
AC_CACHE_CHECK([whether modf works according to ISO C 99 with IEC 60559],
[gl_cv_func_modf_ieee],
[
save_LIBS="$LIBS"
LIBS="$LIBS $MODF_LIBM"
AC_RUN_IFELSE(
[AC_LANG_SOURCE([[
#ifndef __NO_MATH_INLINES
# define __NO_MATH_INLINES 1 /* for glibc */
#endif
#include <math.h>
]gl_DOUBLE_MINUS_ZERO_CODE[
]gl_DOUBLE_SIGNBIT_CODE[
/* Compare two numbers with ==.
This is a separate function because IRIX 6.5 "cc -O" miscompiles an
'x == x' test. */
static int
numeric_equal (double x, double y)
{
return x == y;
}
static double dummy (double x, double *iptr) { return 0; }
double zero;
double minus_one = - 1.0;
int main (int argc, char *argv[])
{
double (* volatile my_modf) (double, double *) = argc ? modf : dummy;
int result = 0;
double i;
double f;
/* Test modf(NaN,...).
This test fails on NetBSD 5.1, Cygwin. */
f = my_modf (zero / zero, &i);
if (numeric_equal (f, f))
result |= 1;
/* Test modf(-Inf,...).
This test fails on FreeBSD 6.4, OpenBSD 6.7, IRIX 6.5, OSF/1 5.1. */
f = my_modf (minus_one / zero, &i);
if (!(f == 0.0) || (signbitd (minus_zerod) && !signbitd (f)))
result |= 2;
return result;
}
]])],
[gl_cv_func_modf_ieee=yes],
[gl_cv_func_modf_ieee=no],
[case "$host_os" in
# Guess yes on glibc systems.
*-gnu* | gnu*) gl_cv_func_modf_ieee="guessing yes" ;;
# Guess yes on musl systems.
*-musl* | midipix*) gl_cv_func_modf_ieee="guessing yes" ;;
# Guess yes on MSVC, no on mingw.
mingw*) AC_EGREP_CPP([Known], [
#ifdef _MSC_VER
Known
#endif
],
[gl_cv_func_modf_ieee="guessing yes"],
[gl_cv_func_modf_ieee="guessing no"])
;;
# If we don't know, obey --enable-cross-guesses.
*) gl_cv_func_modf_ieee="$gl_cross_guess_normal" ;;
esac
])
LIBS="$save_LIBS"
])
case "$gl_cv_func_modf_ieee" in
*yes) ;;
*) REPLACE_MODF=1 ;;
esac
fi
])
if test $REPLACE_MODF = 1; then
dnl Find libraries needed to link lib/modf.c.
AC_REQUIRE([gl_FUNC_TRUNC])
MODF_LIBM="$TRUNC_LIBM"
fi
])
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