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# log2f.m4 serial 3
dnl Copyright (C) 2010-2016 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_LOG2F],
[
m4_divert_text([DEFAULTS], [gl_log2f_required=plain])
AC_REQUIRE([gl_MATH_H_DEFAULTS])
AC_REQUIRE([gl_FUNC_LOG2])
dnl Persuade glibc <math.h> to declare log2f().
AC_REQUIRE([gl_USE_SYSTEM_EXTENSIONS])
dnl Determine LOG2F_LIBM.
gl_COMMON_DOUBLE_MATHFUNC([log2f])
dnl Test whether log2f() exists.
save_LIBS="$LIBS"
LIBS="$LIBS $LOG2F_LIBM"
AC_CHECK_FUNCS([log2f])
LIBS="$save_LIBS"
if test $ac_cv_func_log2f = yes; then
HAVE_LOG2F=1
dnl Also check whether it's declared.
dnl IRIX 6.5 has log2f() in libm but doesn't declare it in <math.h>.
AC_CHECK_DECL([log2f], , [HAVE_DECL_LOG2F=0], [[#include <math.h>]])
save_LIBS="$LIBS"
LIBS="$LIBS $LOG2F_LIBM"
gl_FUNC_LOG2F_WORKS
LIBS="$save_LIBS"
case "$gl_cv_func_log2f_works" in
*yes) ;;
*) REPLACE_LOG2F=1 ;;
esac
m4_ifdef([gl_FUNC_LOG2F_IEEE], [
if test $gl_log2f_required = ieee && test $REPLACE_LOG2F = 0; then
AC_REQUIRE([AC_CANONICAL_HOST]) dnl for cross-compiles
AC_CACHE_CHECK([whether log2f works according to ISO C 99 with IEC 60559],
[gl_cv_func_log2f_ieee],
[
save_LIBS="$LIBS"
LIBS="$LIBS $LOG2F_LIBM"
AC_RUN_IFELSE(
[AC_LANG_SOURCE([[
#ifndef __NO_MATH_INLINES
# define __NO_MATH_INLINES 1 /* for glibc */
#endif
#include <math.h>
#ifndef log2f /* for Cygwin 1.7.x */
extern
#ifdef __cplusplus
"C"
#endif
float log2f (float);
#endif
/* Compare two numbers with ==.
This is a separate function because IRIX 6.5 "cc -O" miscompiles an
'x == x' test. */
static int
numeric_equal (float x, float y)
{
return x == y;
}
static float dummy (float x) { return 0; }
int main (int argc, char *argv[])
{
float (*my_log2f) (float) = argc ? log2f : dummy;
/* Test log2f(negative).
This test fails on NetBSD 5.1 and Solaris 11 2011-11. */
float y = my_log2f (-1.0f);
if (numeric_equal (y, y))
return 1;
return 0;
}
]])],
[gl_cv_func_log2f_ieee=yes],
[gl_cv_func_log2f_ieee=no],
[case "$host_os" in
# Guess yes on glibc systems.
*-gnu*) gl_cv_func_log2f_ieee="guessing yes" ;;
# If we don't know, assume the worst.
*) gl_cv_func_log2f_ieee="guessing no" ;;
esac
])
LIBS="$save_LIBS"
])
case "$gl_cv_func_log2f_ieee" in
*yes) ;;
*) REPLACE_LOG2F=1 ;;
esac
fi
])
else
HAVE_LOG2F=0
HAVE_DECL_LOG2F=0
fi
if test $HAVE_LOG2F = 0 || test $REPLACE_LOG2F = 1; then
dnl Find libraries needed to link lib/log2f.c.
if test $ac_cv_func_log2 = yes; then
AC_DEFINE([HAVE_LOG2], [1],
[Define to 1 if the log2() function is available in libc or libm.])
LOG2F_LIBM="$LOG2_LIBM"
else
AC_REQUIRE([gl_FUNC_ISNANF])
AC_REQUIRE([gl_FUNC_FREXPF])
AC_REQUIRE([gl_FUNC_LOGF])
LOG2F_LIBM=
dnl Append $ISNANF_LIBM to LOG2F_LIBM, avoiding gratuitous duplicates.
case " $LOG2F_LIBM " in
*" $ISNANF_LIBM "*) ;;
*) LOG2F_LIBM="$LOG2F_LIBM $ISNANF_LIBM" ;;
esac
dnl Append $FREXPF_LIBM to LOG2F_LIBM, avoiding gratuitous duplicates.
case " $LOG2F_LIBM " in
*" $FREXPF_LIBM "*) ;;
*) LOG2F_LIBM="$LOG2F_LIBM $FREXPF_LIBM" ;;
esac
dnl Append $LOGF_LIBM to LOG2F_LIBM, avoiding gratuitous duplicates.
case " $LOG2F_LIBM " in
*" $LOGF_LIBM "*) ;;
*) LOG2F_LIBM="$LOG2F_LIBM $LOGF_LIBM" ;;
esac
fi
fi
])
dnl Test whether log2() works.
dnl On OSF/1 5.1, log2f(-0.0f) is NaN.
dnl On Cygwin 1.7.9, log2f(2^13) is not exactly 13.
AC_DEFUN([gl_FUNC_LOG2F_WORKS],
[
AC_REQUIRE([AC_PROG_CC])
AC_REQUIRE([AC_CANONICAL_HOST]) dnl for cross-compiles
AC_CACHE_CHECK([whether log2f works], [gl_cv_func_log2f_works],
[
AC_RUN_IFELSE(
[AC_LANG_SOURCE([[
#include <math.h>
#ifndef log2f /* for Cygwin 1.7.x */
extern
#ifdef __cplusplus
"C"
#endif
float log2f (float);
#endif
volatile float x;
volatile float y;
int main ()
{
int result = 0;
/* This test fails on OSF/1 5.1. */
x = -0.0f;
y = log2f (x);
if (!(y + y == y))
result |= 1;
/* This test fails on Cygwin 1.7.9. */
x = 8192.0f;
y = log2f (x);
if (!(y == 13.0f))
result |= 2;
return result;
}
]])],
[gl_cv_func_log2f_works=yes],
[gl_cv_func_log2f_works=no],
[case "$host_os" in
cygwin* | osf*) gl_cv_func_log2f_works="guessing no";;
*) gl_cv_func_log2f_works="guessing yes";;
esac
])
])
])
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