-# log2f.m4 serial 1
+# log2f.m4 serial 2
dnl Copyright (C) 2010-2012 Free Software Foundation, Inc.
dnl This file is free software; the Free Software Foundation
dnl gives unlimited permission to copy and/or distribute it,
AC_DEFUN([gl_FUNC_LOG2F],
[
+ m4_divert_text([DEFAULTS], [gl_log2f_required=plain])
AC_REQUIRE([gl_MATH_H_DEFAULTS])
AC_REQUIRE([gl_FUNC_LOG2])
*yes) ;;
*) REPLACE_LOG2F=1 ;;
esac
+
+ m4_ifdef([gl_FUNC_LOG2F_IEEE], [
+ if test $gl_log2f_required = ieee && test $REPLACE_LOG2F = 0; then
+ AC_CACHE_CHECK([whether log2f works according to ISO C 99 with IEC 60559],
+ [gl_cv_func_log2f_ieee],
+ [
+ save_LIBS="$LIBS"
+ LIBS="$LIBS $LOG2F_LIBM"
+ AC_RUN_IFELSE(
+ [AC_LANG_SOURCE([[
+#ifndef __NO_MATH_INLINES
+# define __NO_MATH_INLINES 1 /* for glibc */
+#endif
+#include <math.h>
+#ifndef log2f /* for Cygwin 1.7.x */
+extern
+#ifdef __cplusplus
+"C"
+#endif
+float log2f (float);
+#endif
+/* Compare two numbers with ==.
+ This is a separate function because IRIX 6.5 "cc -O" miscompiles an
+ 'x == x' test. */
+static int
+numeric_equal (float x, float y)
+{
+ return x == y;
+}
+static float dummy (float x) { return 0; }
+int main (int argc, char *argv[])
+{
+ float (*my_log2f) (float) = argc ? log2f : dummy;
+ /* Test log2f(negative).
+ This test fails on NetBSD 5.1 and Solaris 11 2011-11. */
+ float y = my_log2f (-1.0f);
+ if (numeric_equal (y, y))
+ return 1;
+ return 0;
+}
+ ]])],
+ [gl_cv_func_log2f_ieee=yes],
+ [gl_cv_func_log2f_ieee=no],
+ [gl_cv_func_log2f_ieee="guessing no"])
+ LIBS="$save_LIBS"
+ ])
+ case "$gl_cv_func_log2f_ieee" in
+ *yes) ;;
+ *) REPLACE_LOG2F=1 ;;
+ esac
+ fi
+ ])
else
HAVE_LOG2F=0
HAVE_DECL_LOG2F=0