X-Git-Url: http://erislabs.net/gitweb/?a=blobdiff_plain;f=m4%2Ffloor.m4;h=5de0da27799f0c5449c31e2b6fdd9d17229035bd;hb=c6f9e663d25b0980c51f609a3fe237deca168461;hp=754133582cdcac50a75519ecc7ca126cc079fde0;hpb=ec062d7a2671739dd977ebde3965fc93f8678a2e;p=gnulib.git

diff --git a/m4/floor.m4 b/m4/floor.m4
index 754133582..5de0da277 100644
--- a/m4/floor.m4
+++ b/m4/floor.m4
@@ -1,16 +1,58 @@
-# floor.m4 serial 4
-dnl Copyright (C) 2007, 2009, 2010 Free Software Foundation, Inc.
+# floor.m4 serial 7
+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_FLOOR],
 [
+  m4_divert_text([DEFAULTS], [gl_floor_required=plain])
+  AC_REQUIRE([gl_MATH_H_DEFAULTS])
   dnl Test whether floor() can be used without libm.
   gl_FUNC_FLOOR_LIBS
   if test "$FLOOR_LIBM" = "?"; then
     FLOOR_LIBM=
   fi
+  m4_ifdef([gl_FUNC_FLOOR_IEEE], [
+    if test $gl_floor_required = ieee && test $REPLACE_FLOOR = 0; then
+      AC_CACHE_CHECK([whether floor works according to ISO C 99 with IEC 60559],
+        [gl_cv_func_floor_ieee],
+        [
+          save_LIBS="$LIBS"
+          LIBS="$LIBS $FLOOR_LIBM"
+          AC_RUN_IFELSE(
+            [AC_LANG_SOURCE([[
+#ifndef __NO_MATH_INLINES
+# define __NO_MATH_INLINES 1 /* for glibc */
+#endif
+#include <math.h>
+]gl_DOUBLE_MINUS_ZERO_CODE[
+]gl_DOUBLE_SIGNBIT_CODE[
+static double dummy (double f) { return 0; }
+int main (int argc, char *argv[])
+{
+  double (*my_floor) (double) = argc ? floor : dummy;
+  /* Test whether floor (-0.0) is -0.0.  */
+  if (signbitd (minus_zerod) && !signbitd (my_floor (minus_zerod)))
+    return 1;
+  return 0;
+}
+            ]])],
+            [gl_cv_func_floor_ieee=yes],
+            [gl_cv_func_floor_ieee=no],
+            [gl_cv_func_floor_ieee="guessing no"])
+          LIBS="$save_LIBS"
+        ])
+      case "$gl_cv_func_floor_ieee" in
+        *yes) ;;
+        *) REPLACE_FLOOR=1 ;;
+      esac
+    fi
+  ])
+  if test $REPLACE_FLOOR = 1; then
+    dnl No libraries are needed to link lib/floor.c.
+    FLOOR_LIBM=
+  fi
   AC_SUBST([FLOOR_LIBM])
 ])