X-Git-Url: http://erislabs.net/gitweb/?a=blobdiff_plain;f=m4%2Ftruncf.m4;h=3920fcd469e75e60a6fce7e39ca33540341651f2;hb=39e1adf83f9afbbc1ab9edbd6ca3d509c1f1bec4;hp=0b7c49ab2facf462a37bca85d74f47bbfa89769f;hpb=ec062d7a2671739dd977ebde3965fc93f8678a2e;p=gnulib.git

diff --git a/m4/truncf.m4 b/m4/truncf.m4
index 0b7c49ab2..3920fcd46 100644
--- a/m4/truncf.m4
+++ b/m4/truncf.m4
@@ -1,11 +1,12 @@
-# truncf.m4 serial 3
-dnl Copyright (C) 2007, 2010 Free Software Foundation, Inc.
+# truncf.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_TRUNCF],
 [
+  m4_divert_text([DEFAULTS], [gl_truncf_required=plain])
   AC_REQUIRE([gl_MATH_H_DEFAULTS])
   dnl Persuade glibc <math.h> to declare truncf().
   AC_REQUIRE([gl_USE_SYSTEM_EXTENSIONS])
@@ -40,9 +41,45 @@ AC_DEFUN([gl_FUNC_TRUNCF],
     if test "$TRUNCF_LIBM" = "?"; then
       TRUNCF_LIBM=
     fi
+    m4_ifdef([gl_FUNC_TRUNCF_IEEE], [
+      if test $gl_truncf_required = ieee && test $REPLACE_TRUNCF = 0; then
+        AC_CACHE_CHECK([whether truncf works according to ISO C 99 with IEC 60559],
+          [gl_cv_func_truncf_ieee],
+          [
+            save_LIBS="$LIBS"
+            LIBS="$LIBS $TRUNCF_LIBM"
+            AC_RUN_IFELSE(
+              [AC_LANG_SOURCE([[
+#ifndef __NO_MATH_INLINES
+# define __NO_MATH_INLINES 1 /* for glibc */
+#endif
+#include <math.h>
+]gl_FLOAT_MINUS_ZERO_CODE[
+]gl_FLOAT_SIGNBIT_CODE[
+int main()
+{
+  /* Test whether truncf (-0.0f) is -0.0f.  */
+  if (signbitf (minus_zerof) && !signbitf (truncf (minus_zerof)))
+    return 1;
+  return 0;
+}
+              ]])],
+              [gl_cv_func_truncf_ieee=yes],
+              [gl_cv_func_truncf_ieee=no],
+              [gl_cv_func_truncf_ieee="guessing no"])
+            LIBS="$save_LIBS"
+          ])
+        case "$gl_cv_func_truncf_ieee" in
+          *yes) ;;
+          *) REPLACE_TRUNCF=1 ;;
+        esac
+      fi
+    ])
   else
     HAVE_DECL_TRUNCF=0
-    AC_LIBOBJ([truncf])
+  fi
+  if test $HAVE_DECL_TRUNCF = 0 || test $REPLACE_TRUNCF = 1; then
+    dnl No libraries are needed to link lib/truncf.c.
     TRUNCF_LIBM=
   fi
   AC_SUBST([TRUNCF_LIBM])