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# logbl.m4 serial 5
dnl Copyright (C) 2012-2023 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_LOGBL],
[
AC_REQUIRE([gl_MATH_H_DEFAULTS])
AC_REQUIRE([gl_LONG_DOUBLE_VS_DOUBLE])
AC_REQUIRE([gl_FUNC_LOGB])
dnl Persuade glibc <math.h> to declare logbl().
AC_REQUIRE([gl_USE_SYSTEM_EXTENSIONS])
dnl Test whether logbl() exists and determine LOGBL_LIBM. We cannot assume
dnl that logbl(), if it exists, is defined in the same library as logb().
dnl This is not the case on AIX >= 5.2, Solaris >= 10.
gl_MATHFUNC([logbl], [long double], [(long double)])
if test $gl_cv_func_logbl_no_libm = yes \
|| test $gl_cv_func_logbl_in_libm = yes; then
save_LIBS="$LIBS"
LIBS="$LIBS $LOGBL_LIBM"
gl_FUNC_LOGBL_WORKS
LIBS="$save_LIBS"
case "$gl_cv_func_logbl_works" in
*yes) ;;
*) REPLACE_LOGBL=1 ;;
esac
else
HAVE_LOGBL=0
fi
if test $HAVE_LOGBL = 0 || test $REPLACE_LOGBL = 1; then
dnl Find libraries needed to link lib/logbl.c.
if test $HAVE_SAME_LONG_DOUBLE_AS_DOUBLE = 1; then
LOGBL_LIBM="$LOGB_LIBM"
else
AC_REQUIRE([gl_FUNC_FREXPL])
AC_REQUIRE([gl_FUNC_ISNANL])
LOGBL_LIBM=
dnl Append $FREXPL_LIBM to LOGBL_LIBM, avoiding gratuitous duplicates.
case " $LOGBL_LIBM " in
*" $FREXPL_LIBM "*) ;;
*) LOGBL_LIBM="$LOGBL_LIBM $FREXPL_LIBM" ;;
esac
dnl Append $ISNANL_LIBM to LOGBL_LIBM, avoiding gratuitous duplicates.
case " $LOGBL_LIBM " in
*" $ISNANL_LIBM "*) ;;
*) LOGBL_LIBM="$LOGBL_LIBM $ISNANL_LIBM" ;;
esac
fi
fi
AC_SUBST([LOGBL_LIBM])
])
dnl Test whether logbl() works.
dnl On glibc 2.11/powerpc, glibc 2.7/sparc, glibc 2.7/hppa, Solaris 10/SPARC,
dnl Solaris 11.4/x86_64, the return value for subnormal (denormalized) arguments
dnl is too large.
dnl On glibc 2.23/powerpc64le, the return value for negative subnormal arguments
dnl is too large.
AC_DEFUN([gl_FUNC_LOGBL_WORKS],
[
AC_REQUIRE([AC_PROG_CC])
AC_REQUIRE([AC_CANONICAL_HOST]) dnl for cross-compiles
AC_CACHE_CHECK([whether logbl works], [gl_cv_func_logbl_works],
[
AC_RUN_IFELSE(
[AC_LANG_SOURCE([[
#include <float.h>
#include <math.h>
/* Override the values of <float.h>, like done in float.in.h. */
#if defined __i386__ && (defined __BEOS__ || defined __OpenBSD__)
# undef LDBL_MIN_EXP
# define LDBL_MIN_EXP (-16381)
#endif
#if defined __i386__ && (defined __FreeBSD__ || defined __DragonFly__)
# undef LDBL_MIN_EXP
# define LDBL_MIN_EXP (-16381)
#endif
#if (defined _ARCH_PPC || defined _POWER) && defined _AIX && (LDBL_MANT_DIG == 106) && defined __GNUC__
# undef LDBL_MIN_EXP
# define LDBL_MIN_EXP DBL_MIN_EXP
#endif
#if defined __sgi && (LDBL_MANT_DIG >= 106)
# if defined __GNUC__
# undef LDBL_MIN_EXP
# define LDBL_MIN_EXP DBL_MIN_EXP
# endif
#endif
volatile long double x;
int main ()
{
int i;
for (i = 1, x = 1.0L; i >= LDBL_MIN_EXP - 54; i--, x *= 0.5L)
/* Either x = 2^(i-1) or x = 0.0. */
if ((i == LDBL_MIN_EXP - 1 || i == LDBL_MIN_EXP - 54)
&& (x > 0.0L && !(logbl (x) == (long double)(i - 1))))
return 1;
for (i = 1, x = -1.0L; i >= LDBL_MIN_EXP - 54; i--, x *= 0.5L)
/* Either x = -2^(i-1) or x = 0.0. */
if ((i == LDBL_MIN_EXP - 1 || i == LDBL_MIN_EXP - 54)
&& (x < 0.0L && !(logbl (x) == (long double)(i - 1))))
return 1;
return 0;
}
]])],
[gl_cv_func_logbl_works=yes],
[gl_cv_func_logbl_works=no],
[case "$host_os" in
*gnu* | solaris*) gl_cv_func_logbl_works="guessing no" ;;
# Guess yes on native Windows.
mingw*) gl_cv_func_logbl_works="guessing yes" ;;
*) gl_cv_func_logbl_works="guessing yes" ;;
esac
])
])
])
|
