X-Git-Url: http://erislabs.net/gitweb/?a=blobdiff_plain;f=m4%2Fround.m4;h=a95d905ef6dc0e54554ac620112a107ffb368704;hb=4f8c7a6e29f65cb71eca3092f712c71d580ba936;hp=1d1b91c1a1161f1943314d2e45094d94cc249c11;hpb=b4e5a5f11bd67ce5435b5ecf43b7fb6a81ba62a0;p=gnulib.git

diff --git a/m4/round.m4 b/m4/round.m4
index 1d1b91c1a..a95d905ef 100644
--- a/m4/round.m4
+++ b/m4/round.m4
@@ -1,11 +1,12 @@
-# round.m4 serial 9
-dnl Copyright (C) 2007, 2009-2010 Free Software Foundation, Inc.
+# round.m4 serial 10
+dnl Copyright (C) 2007, 2009-2011 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_ROUND],
 [
+  m4_divert_text([DEFAULTS], [gl_round_required=plain])
   AC_REQUIRE([gl_MATH_H_DEFAULTS])
   dnl Persuade glibc <math.h> to declare round().
   AC_REQUIRE([gl_USE_SYSTEM_EXTENSIONS])
@@ -53,6 +54,40 @@ int main()
     if test "$ROUND_LIBM" = missing; then
       REPLACE_ROUND=1
     fi
+    m4_ifdef([gl_FUNC_ROUND_IEEE], [
+      if test $gl_round_required = ieee && test $REPLACE_ROUND = 0; then
+        AC_CACHE_CHECK([whether round works according to ISO C 99 with IEC 60559],
+          [gl_cv_func_round_ieee],
+          [
+            save_LIBS="$LIBS"
+            LIBS="$LIBS $ROUND_LIBM"
+            AC_RUN_IFELSE(
+              [AC_LANG_SOURCE([[
+#ifndef __NO_MATH_INLINES
+# define __NO_MATH_INLINES 1 /* for glibc */
+#endif
+#include <math.h>
+]gl_DOUBLE_MINUS_ZERO_CODE[
+]gl_DOUBLE_SIGNBIT_CODE[
+int main()
+{
+  /* Test whether round (-0.0) is -0.0.  */
+  if (signbitd (minus_zerod) && !signbitd (round (minus_zerod)))
+    return 1;
+  return 0;
+}
+              ]])],
+              [gl_cv_func_round_ieee=yes],
+              [gl_cv_func_round_ieee=no],
+              [gl_cv_func_round_ieee="guessing no"])
+            LIBS="$save_LIBS"
+          ])
+        case "$gl_cv_func_round_ieee" in
+          *yes) ;;
+          *) REPLACE_ROUND=1 ;;
+        esac
+      fi
+    ])
   else
     HAVE_DECL_ROUND=0
   fi