X-Git-Url: http://erislabs.net/gitweb/?a=blobdiff_plain;ds=sidebyside;f=m4%2Froundf.m4;h=a2a1464e6881d2f88fffcb558c6ffc33441ba29e;hb=12856373f8fd28a9d4453d6df97b2fdd17ced398;hp=5878beb735b08f19e38d582a1e824f2b31cd2ec1;hpb=d924a8c6cc8bb8e5903399494bb2e749ef244b5e;p=gnulib.git

diff --git a/m4/roundf.m4 b/m4/roundf.m4
index 5878beb73..a2a1464e6 100644
--- a/m4/roundf.m4
+++ b/m4/roundf.m4
@@ -1,28 +1,114 @@
-# roundf.m4 serial 4
-dnl Copyright (C) 2007 Free Software Foundation, Inc.
+# roundf.m4 serial 10
+dnl Copyright (C) 2007-2011 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_ROUNDF],
 [
+  m4_divert_text([DEFAULTS], [gl_roundf_required=plain])
   AC_REQUIRE([gl_MATH_H_DEFAULTS])
   dnl Persuade glibc <math.h> to declare roundf().
   AC_REQUIRE([gl_USE_SYSTEM_EXTENSIONS])
   AC_CHECK_DECLS([roundf], , , [#include <math.h>])
   if test "$ac_cv_have_decl_roundf" = yes; then
     gl_CHECK_MATH_LIB([ROUNDF_LIBM], [x = roundf (x);])
+    if test "$ROUNDF_LIBM" != missing; then
+      dnl Test whether roundf() produces correct results. On mingw, for
+      dnl x = 1/2 - 2^-25, the system's roundf() returns a wrong result.
+      AC_REQUIRE([AC_PROG_CC])
+      AC_REQUIRE([AC_CANONICAL_HOST]) dnl for cross-compiles
+      AC_CACHE_CHECK([whether roundf works], [gl_cv_func_roundf_works],
+        [
+          save_LIBS="$LIBS"
+          LIBS="$LIBS $ROUNDF_LIBM"
+          AC_RUN_IFELSE([AC_LANG_SOURCE([[
+#include <float.h>
+#include <math.h>
+int main()
+{
+  /* 2^FLT_MANT_DIG.  */
+  static const float TWO_MANT_DIG =
+    /* Assume FLT_MANT_DIG <= 3 * 31.
+       Use the identity  n = floor(n/3) + floor((n+1)/3) + floor((n+2)/3).  */
+    (float) (1U << (FLT_MANT_DIG / 3))
+    * (float) (1U << ((FLT_MANT_DIG + 1) / 3))
+    * (float) (1U << ((FLT_MANT_DIG + 2) / 3));
+  volatile float x = 0.5f - 0.5f / TWO_MANT_DIG;
+  exit (x < 0.5f && roundf (x) != 0.0f);
+}]])], [gl_cv_func_roundf_works=yes], [gl_cv_func_roundf_works=no],
+          [case "$host_os" in
+             mingw*) gl_cv_func_roundf_works="guessing no";;
+             *)      gl_cv_func_roundf_works="guessing yes";;
+           esac
+          ])
+          LIBS="$save_LIBS"
+        ])
+      case "$gl_cv_func_roundf_works" in
+        *no) ROUNDF_LIBM=missing ;;
+      esac
+    fi
+    if test "$ROUNDF_LIBM" = missing; then
+      REPLACE_ROUNDF=1
+    fi
+    m4_ifdef([gl_FUNC_ROUNDF_IEEE], [
+      if test $gl_roundf_required = ieee && test $REPLACE_ROUNDF = 0; then
+        AC_CACHE_CHECK([whether roundf works according to ISO C 99 with IEC 60559],
+          [gl_cv_func_roundf_ieee],
+          [
+            save_LIBS="$LIBS"
+            LIBS="$LIBS $ROUNDF_LIBM"
+            AC_RUN_IFELSE(
+              [AC_LANG_SOURCE([[
+#ifndef __NO_MATH_INLINES
+# define __NO_MATH_INLINES 1 /* for glibc */
+#endif
+#include <math.h>
+]gl_FLOAT_MINUS_ZERO_CODE[
+]gl_FLOAT_SIGNBIT_CODE[
+int main()
+{
+  /* Test whether roundf (-0.0f) is -0.0f.  */
+  if (signbitf (minus_zerof) && !signbitf (roundf (minus_zerof)))
+    return 1;
+  return 0;
+}
+              ]])],
+              [gl_cv_func_roundf_ieee=yes],
+              [gl_cv_func_roundf_ieee=no],
+              [gl_cv_func_roundf_ieee="guessing no"])
+            LIBS="$save_LIBS"
+          ])
+        case "$gl_cv_func_roundf_ieee" in
+          *yes) ;;
+          *) REPLACE_ROUNDF=1 ;;
+        esac
+      fi
+    ])
+  else
+    HAVE_DECL_ROUNDF=0
   fi
-  if test "$ac_cv_have_decl_roundf" != yes || test "$ROUNDF_LIBM" = missing; then
-    REPLACE_ROUNDF=1
+  if test $HAVE_DECL_ROUNDF = 0 || test $REPLACE_ROUNDF = 1; then
     AC_LIBOBJ([roundf])
     AC_CHECK_DECLS([ceilf, floorf], , , [#include <math.h>])
     if test "$ac_cv_have_decl_floorf" = yes \
        && test "$ac_cv_have_decl_ceilf" = yes; then
-      gl_CHECK_MATH_LIB([ROUNDF_LIBM], [x = floorf (x) + ceilf (x);])
-      if test "$ROUNDF_LIBM" != missing; then
-        AC_DEFINE([HAVE_FLOORF_AND_CEILF], 1,
+      gl_FUNC_FLOORF_LIBS
+      gl_FUNC_CEILF_LIBS
+      if test "$FLOORF_LIBM" != '?' && test "$CEILF_LIBM" != '?'; then
+        AC_DEFINE([HAVE_FLOORF_AND_CEILF], [1],
           [Define if the both the floorf() and ceilf() functions exist.])
+        ROUNDF_LIBM=
+        dnl Append $FLOORF_LIBM to ROUNDF_LIBM, avoiding gratuitous duplicates.
+        case " $ROUNDF_LIBM " in
+          *" $FLOORF_LIBM "*) ;;
+          *) ROUNDF_LIBM="$ROUNDF_LIBM $FLOORF_LIBM" ;;
+        esac
+        dnl Append $CEILF_LIBM to ROUNDF_LIBM, avoiding gratuitous duplicates.
+        case " $ROUNDF_LIBM " in
+          *" $CEILF_LIBM "*) ;;
+          *) ROUNDF_LIBM="$ROUNDF_LIBM $CEILF_LIBM" ;;
+        esac
       else
         ROUNDF_LIBM=
       fi