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# ilogbl.m4 serial 1
dnl Copyright (C) 2010-2017 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_ILOGBL],
[
AC_REQUIRE([gl_MATH_H_DEFAULTS])
AC_REQUIRE([gl_LONG_DOUBLE_VS_DOUBLE])
AC_REQUIRE([gl_FUNC_ILOGB])
dnl Persuade glibc <math.h> to declare ilogbl().
AC_REQUIRE([gl_USE_SYSTEM_EXTENSIONS])
dnl Test whether ilogbl() exists. Assume that ilogbl(), if it exists, is
dnl defined in the same library as ilogb().
save_LIBS="$LIBS"
LIBS="$LIBS $ILOGB_LIBM"
AC_CACHE_CHECK([for ilogbl],
[gl_cv_func_ilogbl],
[
AC_LINK_IFELSE(
[AC_LANG_PROGRAM(
[[#ifndef __NO_MATH_INLINES
# define __NO_MATH_INLINES 1 /* for glibc */
#endif
#include <math.h>
int (*funcptr) (long double) = ilogbl;
long double x;]],
[[return (funcptr (x) % 2) == 0
|| (ilogbl (x) % 2) == 0;]])],
[gl_cv_func_ilogbl=yes],
[gl_cv_func_ilogbl=no])
])
LIBS="$save_LIBS"
if test $gl_cv_func_ilogbl = yes; then
ILOGBL_LIBM="$ILOGB_LIBM"
else
HAVE_ILOGBL=0
dnl Find libraries needed to link lib/ilogbl.c.
if test $HAVE_SAME_LONG_DOUBLE_AS_DOUBLE = 1; then
ILOGBL_LIBM="$ILOGB_LIBM"
else
AC_REQUIRE([gl_FUNC_FREXPL])
AC_REQUIRE([gl_FUNC_ISNANL])
ILOGBL_LIBM=
dnl Append $FREXPL_LIBM to ILOGBL_LIBM, avoiding gratuitous duplicates.
case " $ILOGBL_LIBM " in
*" $FREXPL_LIBM "*) ;;
*) ILOGBL_LIBM="$ILOGBL_LIBM $FREXPL_LIBM" ;;
esac
dnl Append $ISNANL_LIBM to ILOGBL_LIBM, avoiding gratuitous duplicates.
case " $ILOGBL_LIBM " in
*" $ISNANL_LIBM "*) ;;
*) ILOGBL_LIBM="$ILOGBL_LIBM $ISNANL_LIBM" ;;
esac
fi
fi
AC_SUBST([ILOGBL_LIBM])
])
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