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# ilogb.m4 serial 7
dnl Copyright (C) 2010-2023 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_ILOGB],
[
AC_REQUIRE([gl_MATH_H_DEFAULTS])
dnl Determine ILOGB_LIBM.
gl_MATHFUNC([ilogb], [int], [(double)])
if test $gl_cv_func_ilogb_no_libm = yes \
|| test $gl_cv_func_ilogb_in_libm = yes; then
save_LIBS="$LIBS"
LIBS="$LIBS $ILOGB_LIBM"
gl_FUNC_ILOGB_WORKS
LIBS="$save_LIBS"
case "$gl_cv_func_ilogb_works" in
*yes) ;;
*) REPLACE_ILOGB=1 ;;
esac
else
HAVE_ILOGB=0
fi
if test $HAVE_ILOGB = 0 || test $REPLACE_ILOGB = 1; then
dnl Find libraries needed to link lib/ilogb.c.
AC_REQUIRE([gl_FUNC_FREXP])
AC_REQUIRE([gl_FUNC_ISNAND])
ILOGB_LIBM=
dnl Append $FREXP_LIBM to ILOGB_LIBM, avoiding gratuitous duplicates.
case " $ILOGB_LIBM " in
*" $FREXP_LIBM "*) ;;
*) ILOGB_LIBM="$ILOGB_LIBM $FREXP_LIBM" ;;
esac
dnl Append $ISNAND_LIBM to ILOGB_LIBM, avoiding gratuitous duplicates.
case " $ILOGB_LIBM " in
*" $ISNAND_LIBM "*) ;;
*) ILOGB_LIBM="$ILOGB_LIBM $ISNAND_LIBM" ;;
esac
fi
AC_SUBST([ILOGB_LIBM])
])
dnl Test whether ilogb() works.
dnl On OpenBSD 6.7, AIX 5.1, ilogb(0.0) is wrong.
dnl On AIX 7.1 in 64-bit mode, ilogb(2^(DBL_MIN_EXP-1)) is wrong.
dnl On NetBSD 7.1, OpenBSD 6.7, ilogb(Infinity) is wrong.
dnl On NetBSD 7.1, OpenBSD 6.7, ilogb(NaN) is wrong.
AC_DEFUN([gl_FUNC_ILOGB_WORKS],
[
AC_REQUIRE([AC_PROG_CC])
AC_REQUIRE([AC_CANONICAL_HOST]) dnl for cross-compiles
AC_CACHE_CHECK([whether ilogb works], [gl_cv_func_ilogb_works],
[
AC_RUN_IFELSE(
[AC_LANG_SOURCE([[
#include <float.h>
#include <limits.h>
#include <math.h>
/* Provide FP_ILOGB0, FP_ILOGBNAN, like in math.in.h. */
#if defined FP_ILOGB0 && defined FP_ILOGBNAN
# if defined __HAIKU__
/* Haiku: match what ilogb() does */
# undef FP_ILOGB0
# undef FP_ILOGBNAN
# define FP_ILOGB0 (- 2147483647 - 1) /* INT_MIN */
# define FP_ILOGBNAN (- 2147483647 - 1) /* INT_MIN */
# endif
#else
# if defined __NetBSD__ || defined __sgi
/* NetBSD, IRIX 6.5: match what ilogb() does */
# define FP_ILOGB0 INT_MIN
# define FP_ILOGBNAN INT_MIN
# elif defined _AIX
/* AIX 5.1: match what ilogb() does in AIX >= 5.2 */
# define FP_ILOGB0 INT_MIN
# define FP_ILOGBNAN INT_MAX
# elif defined __sun
/* Solaris 9: match what ilogb() does */
# define FP_ILOGB0 (- INT_MAX)
# define FP_ILOGBNAN INT_MAX
# endif
#endif
volatile double x;
static double zero;
static int dummy (double x) { return 0; }
int main (int argc, char *argv[])
{
int (* volatile my_ilogb) (double) = argc ? ilogb : dummy;
int result = 0;
/* This test fails on OpenBSD 6.7, AIX 5.1. */
{
x = 0.0;
if (my_ilogb (x) != FP_ILOGB0)
result |= 1;
}
/* This test fails on AIX 7.1 in 64-bit mode. */
{
int i;
x = 0.5;
for (i = DBL_MIN_EXP - 1; i < 0; i++)
x = x * 0.5;
if (x > 0.0 && my_ilogb (x) != DBL_MIN_EXP - 2)
result |= 2;
}
/* This test fails on NetBSD 7.1, OpenBSD 6.7. */
{
x = 1.0 / zero;
if (my_ilogb (x) != INT_MAX)
result |= 4;
}
/* This test fails on NetBSD 7.1, OpenBSD 6.7. */
{
x = zero / zero;
if (my_ilogb (x) != FP_ILOGBNAN)
result |= 8;
}
return result;
}
]])],
[gl_cv_func_ilogb_works=yes],
[gl_cv_func_ilogb_works=no],
[case "$host_os" in
aix* | openbsd* | netbsd* | solaris*)
gl_cv_func_ilogb_works="guessing no" ;;
# Guess yes on native Windows.
mingw*) gl_cv_func_ilogb_works="guessing yes" ;;
*) gl_cv_func_ilogb_works="guessing yes" ;;
esac
])
])
])
|
