X-Git-Url: http://erislabs.net/gitweb/?a=blobdiff_plain;ds=sidebyside;f=m4%2Ftrunc.m4;h=e1069115ca5cca79c06905dbdbe1e23ed0c188b4;hb=6f0680eb29a1737d704a1df26aafc00490cd34d8;hp=0654d9cd2140109a55752a204bacc19572dbcd18;hpb=ec062d7a2671739dd977ebde3965fc93f8678a2e;p=gnulib.git

diff --git a/m4/trunc.m4 b/m4/trunc.m4
index 0654d9cd2..e1069115c 100644
--- a/m4/trunc.m4
+++ b/m4/trunc.m4
@@ -1,11 +1,12 @@
-# trunc.m4 serial 4
-dnl Copyright (C) 2007, 2010 Free Software Foundation, Inc.
+# trunc.m4 serial 5
+dnl Copyright (C) 2007, 2010-2011 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_TRUNC],
 [
+  m4_divert_text([DEFAULTS], [gl_trunc_required=plain])
   AC_REQUIRE([gl_MATH_H_DEFAULTS])
   dnl Persuade glibc <math.h> to declare trunc().
   AC_REQUIRE([gl_USE_SYSTEM_EXTENSIONS])
@@ -40,8 +41,44 @@ AC_DEFUN([gl_FUNC_TRUNC],
     if test "$TRUNC_LIBM" = "?"; then
       TRUNC_LIBM=
     fi
+    m4_ifdef([gl_FUNC_TRUNC_IEEE], [
+      if test $gl_trunc_required = ieee && test $REPLACE_TRUNC = 0; then
+        AC_CACHE_CHECK([whether trunc works according to ISO C 99 with IEC 60559],
+          [gl_cv_func_trunc_ieee],
+          [
+            save_LIBS="$LIBS"
+            LIBS="$LIBS $TRUNC_LIBM"
+            AC_RUN_IFELSE(
+              [AC_LANG_SOURCE([[
+#ifndef __NO_MATH_INLINES
+# define __NO_MATH_INLINES 1 /* for glibc */
+#endif
+#include <math.h>
+]gl_DOUBLE_MINUS_ZERO_CODE[
+]gl_DOUBLE_SIGNBIT_CODE[
+int main()
+{
+  /* Test whether trunc (-0.0) is -0.0.  */
+  if (signbitd (minus_zerod) && !signbitd (trunc (minus_zerod)))
+    return 1;
+  return 0;
+}
+              ]])],
+              [gl_cv_func_trunc_ieee=yes],
+              [gl_cv_func_trunc_ieee=no],
+              [gl_cv_func_trunc_ieee="guessing no"])
+            LIBS="$save_LIBS"
+          ])
+        case "$gl_cv_func_trunc_ieee" in
+          *yes) ;;
+          *) REPLACE_TRUNC=1 ;;
+        esac
+      fi
+    ])
   else
     HAVE_DECL_TRUNC=0
+  fi
+  if test $HAVE_DECL_TRUNC = 0 || test $REPLACE_TRUNC = 1; then
     AC_LIBOBJ([trunc])
     TRUNC_LIBM=
   fi