+# Check for NAN
+AC_ARG_WITH(nan-emulation, [AS_HELP_STRING([--with-nan-emulation], [use emulated NAN. For crosscompiling only.])],
+[
+ if test "x$withval" = "xno"; then
+ nan_type="none"
+ else if test "x$withval" = "xyes"; then
+ nan_type="zero"
+ else
+ nan_type="$withval"
+ fi; fi
+],
+[nan_type="none"])
+if test "x$nan_type" = "xnone"; then
+ AC_CACHE_CHECK([whether NAN is defined by default],
+ [have_nan_default],
+ AC_COMPILE_IFELSE(
+ AC_LANG_PROGRAM(
+ [[
+#include <stdlib.h>
+#include <math.h>
+static float foo = NAN;
+ ]],
+ [[
+ if (isnan (foo))
+ return 0;
+ else
+ return 1;
+ ]]),
+ [have_nan_default="yes"],
+ [have_nan_default="no"]
+ )
+ )
+ if test "x$have_nan_default" = "xyes"
+ then
+ nan_type="default"
+ fi
+fi
+if test "x$nan_type" = "xnone"; then
+ AC_CACHE_CHECK([whether NAN is defined by __USE_ISOC99],
+ [have_nan_isoc],
+ AC_COMPILE_IFELSE(
+ AC_LANG_PROGRAM(
+ [[
+#include <stdlib.h>
+#define __USE_ISOC99 1
+#include <math.h>
+static float foo = NAN;
+ ]],
+ [[
+ if (isnan (foo))
+ return 0;
+ else
+ return 1;
+ ]]),
+ [have_nan_isoc="yes"],
+ [have_nan_isoc="no"]
+ )
+ )
+ if test "x$have_nan_isoc" = "xyes"
+ then
+ nan_type="isoc99"
+ fi
+fi
+if test "x$nan_type" = "xnone"; then
+ AC_CACHE_CHECK([whether NAN can be defined by 0/0],
+ [have_nan_zero],
+ AC_RUN_IFELSE(
+ AC_LANG_PROGRAM(
+ [[
+#include <stdlib.h>
+#include <math.h>
+#ifdef NAN
+# undef NAN
+#endif
+#define NAN (0.0 / 0.0)
+#ifndef isnan
+# define isnan(f) ((f) != (f))
+#endif
+static float foo = NAN;
+ ]],
+ [[
+ if (isnan (foo))
+ return 0;
+ else
+ return 1;
+ ]]),
+ [have_nan_zero="yes"],
+ [have_nan_zero="no"]
+ )
+ )
+ if test "x$have_nan_zero" = "xyes"
+ then
+ nan_type="zero"
+ fi
+fi
+
+if test "x$nan_type" = "xdefault"; then
+ AC_DEFINE(NAN_STATIC_DEFAULT, 1,
+ [Define if NAN is defined by default and can initialize static variables.])
+else if test "x$nan_type" = "xisoc99"; then
+ AC_DEFINE(NAN_STATIC_ISOC, 1,
+ [Define if NAN is defined by __USE_ISOC99 and can initialize static variables.])
+else if test "x$nan_type" = "xzero"; then
+ AC_DEFINE(NAN_ZERO_ZERO, 1,
+ [Define if NAN can be defined as (0.0 / 0.0)])
+else
+ AC_MSG_ERROR([Didn't find out how to statically initialize variables to NAN. Sorry.])
+fi; fi; fi
+