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# log2l.m4 serial 3
dnl Copyright (C) 2010-2021 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_LOG2L],
[
AC_REQUIRE([gl_MATH_H_DEFAULTS])
AC_REQUIRE([gl_LONG_DOUBLE_VS_DOUBLE])
AC_REQUIRE([gl_FUNC_LOG2])
dnl Persuade glibc <math.h> to declare log2l().
AC_REQUIRE([gl_USE_SYSTEM_EXTENSIONS])
dnl Test whether log2l() exists. Assume that log2l(), if it exists, is
dnl defined in the same library as log2().
save_LIBS="$LIBS"
LIBS="$LIBS $LOG2_LIBM"
AC_CHECK_FUNCS([log2l])
LIBS="$save_LIBS"
if test $ac_cv_func_log2l = yes; then
LOG2L_LIBM="$LOG2_LIBM"
HAVE_LOG2L=1
dnl Also check whether it's declared.
dnl IRIX 6.5 has log2l() in libm but doesn't declare it in <math.h>.
AC_CHECK_DECL([log2l], , [HAVE_DECL_LOG2L=0], [[#include <math.h>]])
save_LIBS="$LIBS"
LIBS="$LIBS $LOG2L_LIBM"
gl_FUNC_LOG2L_WORKS
LIBS="$save_LIBS"
case "$gl_cv_func_log2l_works" in
*yes) ;;
*) REPLACE_LOG2L=1 ;;
esac
else
HAVE_LOG2L=0
HAVE_DECL_LOG2L=0
fi
if test $HAVE_LOG2L = 0 || test $REPLACE_LOG2L = 1; then
dnl Find libraries needed to link lib/log2l.c.
if test $HAVE_SAME_LONG_DOUBLE_AS_DOUBLE = 1; then
LOG2L_LIBM="$LOG2_LIBM"
else
AC_REQUIRE([gl_FUNC_ISNANL])
AC_REQUIRE([gl_FUNC_FREXPL])
AC_REQUIRE([gl_FUNC_LOGL])
LOG2L_LIBM=
dnl Append $ISNANL_LIBM to LOG2L_LIBM, avoiding gratuitous duplicates.
case " $LOG2L_LIBM " in
*" $ISNANL_LIBM "*) ;;
*) LOG2L_LIBM="$LOG2L_LIBM $ISNANL_LIBM" ;;
esac
dnl Append $FREXPL_LIBM to LOG2L_LIBM, avoiding gratuitous duplicates.
case " $LOG2L_LIBM " in
*" $FREXPL_LIBM "*) ;;
*) LOG2L_LIBM="$LOG2L_LIBM $FREXPL_LIBM" ;;
esac
dnl Append $LOGL_LIBM to LOG2L_LIBM, avoiding gratuitous duplicates.
case " $LOG2L_LIBM " in
*" $LOGL_LIBM "*) ;;
*) LOG2L_LIBM="$LOG2L_LIBM $LOGL_LIBM" ;;
esac
fi
fi
AC_SUBST([LOG2L_LIBM])
])
dnl Test whether log2l() works.
dnl On OSF/1 5.1, log2l(-0.0) is NaN.
dnl On musl 1.2.2/{arm64,s390x}, the result is accurate to only 16 digits.
AC_DEFUN([gl_FUNC_LOG2L_WORKS],
[
AC_REQUIRE([AC_PROG_CC])
AC_REQUIRE([AC_CANONICAL_HOST]) dnl for cross-compiles
AC_CACHE_CHECK([whether log2l works], [gl_cv_func_log2l_works],
[
AC_RUN_IFELSE(
[AC_LANG_SOURCE([[
#ifndef __NO_MATH_INLINES
# define __NO_MATH_INLINES 1 /* for glibc */
#endif
#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_MANT_DIG
# define LDBL_MANT_DIG 64
# undef LDBL_MIN_EXP
# define LDBL_MIN_EXP (-16381)
# undef LDBL_MAX_EXP
# define LDBL_MAX_EXP 16384
#endif
#if defined __i386__ && (defined __FreeBSD__ || defined __DragonFly__)
# undef LDBL_MANT_DIG
# define LDBL_MANT_DIG 64
# undef LDBL_MIN_EXP
# define LDBL_MIN_EXP (-16381)
# undef LDBL_MAX_EXP
# define LDBL_MAX_EXP 16384
#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)
# undef LDBL_MANT_DIG
# define LDBL_MANT_DIG 106
# if defined __GNUC__
# undef LDBL_MIN_EXP
# define LDBL_MIN_EXP DBL_MIN_EXP
# endif
#endif
#ifndef log2l /* for AIX */
extern
#ifdef __cplusplus
"C"
#endif
long double log2l (long double);
#endif
static long double dummy (long double x) { return 0; }
volatile long double gx;
volatile long double gy;
int main (int argc, char *argv[])
{
long double (* volatile my_log2l) (long double) = argc ? log2l : dummy;
int result = 0;
/* This test fails on OSF/1 5.1. */
{
gx = -0.0L;
gy = my_log2l (gx);
if (!(gy + gy == gy))
result |= 1;
}
/* This test fails on musl 1.2.2/arm64, musl 1.2.2/s390x. */
{
const long double TWO_LDBL_MANT_DIG = /* 2^LDBL_MANT_DIG */
(long double) (1U << ((LDBL_MANT_DIG - 1) / 5))
* (long double) (1U << ((LDBL_MANT_DIG - 1 + 1) / 5))
* (long double) (1U << ((LDBL_MANT_DIG - 1 + 2) / 5))
* (long double) (1U << ((LDBL_MANT_DIG - 1 + 3) / 5))
* (long double) (1U << ((LDBL_MANT_DIG - 1 + 4) / 5));
long double x = 11.358L;
long double y = my_log2l (x);
long double z = my_log2l (1.0L / x);
long double err = (y + z) * TWO_LDBL_MANT_DIG;
if (!(err >= -10000.0L && err <= 10000.0L))
result |= 2;
}
/* This test fails on musl 1.2.2/arm64, musl 1.2.2/s390x. */
if (DBL_MAX_EXP < LDBL_MAX_EXP)
{
long double x = ldexpl (1.0L, DBL_MAX_EXP); /* finite! */
long double y = my_log2l (x);
if (y > 0 && y + y == y) /* infinite? */
result |= 4;
}
return result;
}
]])],
[gl_cv_func_log2l_works=yes],
[gl_cv_func_log2l_works=no],
[case "$host_os" in
# Guess yes on glibc systems.
*-gnu* | gnu*) gl_cv_func_log2l_works="guessing yes" ;;
# Guess no on musl systems.
*-musl*) gl_cv_func_log2l_works="guessing no" ;;
# Guess no on OSF/1.
osf*) gl_cv_func_log2l_works="guessing no" ;;
# Guess yes on native Windows.
mingw*) gl_cv_func_log2l_works="guessing yes" ;;
# If we don't know, obey --enable-cross-guesses.
*) gl_cv_func_log2l_works="$gl_cross_guess_normal" ;;
esac
])
])
])
|
