X-Git-Url: https://erislabs.net/gitweb/?a=blobdiff_plain;f=m4%2Fmodf.m4;h=20163f7e8c475c86cc9817c413393fd6b4b0de57;hb=3386f3988ce2ab14d65f59659d8f95bf4830ecb3;hp=03ee50b27eafc4cd8a7c84a1361e1f7371fc780d;hpb=e8b58a0f7e4b3ceb67460e953fe443a6ddd52675;p=gnulib.git

diff --git a/m4/modf.m4 b/m4/modf.m4
index 03ee50b27..20163f7e8 100644
--- a/m4/modf.m4
+++ b/m4/modf.m4
@@ -1,11 +1,83 @@
-# modf.m4 serial 1
-dnl Copyright (C) 2011 Free Software Foundation, Inc.
+# modf.m4 serial 3
+dnl Copyright (C) 2011-2013 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_MODF],
 [
+  m4_divert_text([DEFAULTS], [gl_modf_required=plain])
+  AC_REQUIRE([gl_MATH_H_DEFAULTS])
+
   dnl Determine MODF_LIBM.
   gl_MATHFUNC([modf], [double], [(double, double *)])
+
+  m4_ifdef([gl_FUNC_MODF_IEEE], [
+    if test $gl_modf_required = ieee && test $REPLACE_MODF = 0; then
+      AC_REQUIRE([AC_CANONICAL_HOST]) dnl for cross-compiles
+      AC_CACHE_CHECK([whether modf works according to ISO C 99 with IEC 60559],
+        [gl_cv_func_modf_ieee],
+        [
+          save_LIBS="$LIBS"
+          LIBS="$LIBS $MODF_LIBM"
+          AC_RUN_IFELSE(
+            [AC_LANG_SOURCE([[
+#ifndef __NO_MATH_INLINES
+# define __NO_MATH_INLINES 1 /* for glibc */
+#endif
+#include <math.h>
+]gl_DOUBLE_MINUS_ZERO_CODE[
+]gl_DOUBLE_SIGNBIT_CODE[
+/* Compare two numbers with ==.
+   This is a separate function because IRIX 6.5 "cc -O" miscompiles an
+   'x == x' test.  */
+static int
+numeric_equal (double x, double y)
+{
+  return x == y;
+}
+static double dummy (double x, double *iptr) { return 0; }
+double zero;
+double minus_one = - 1.0;
+int main (int argc, char *argv[])
+{
+  double (*my_modf) (double, double *) = argc ? modf : dummy;
+  int result = 0;
+  double i;
+  double f;
+  /* Test modf(NaN,...).
+     This test fails on NetBSD 5.1, Cygwin.  */
+  f = my_modf (zero / zero, &i);
+  if (numeric_equal (f, f))
+    result |= 1;
+  /* Test modf(-Inf,...).
+     This test fails on FreeBSD 6.4, OpenBSD 4.9, IRIX 6.5, OSF/1 5.1.  */
+  f = my_modf (minus_one / zero, &i);
+  if (!(f == 0.0) || (signbitd (minus_zerod) && !signbitd (f)))
+    result |= 2;
+  return result;
+}
+            ]])],
+            [gl_cv_func_modf_ieee=yes],
+            [gl_cv_func_modf_ieee=no],
+            [case "$host_os" in
+                       # Guess yes on glibc systems.
+               *-gnu*) gl_cv_func_modf_ieee="guessing yes" ;;
+                       # If we don't know, assume the worst.
+               *)      gl_cv_func_modf_ieee="guessing no" ;;
+             esac
+            ])
+          LIBS="$save_LIBS"
+        ])
+      case "$gl_cv_func_modf_ieee" in
+        *yes) ;;
+        *) REPLACE_MODF=1 ;;
+      esac
+    fi
+  ])
+  if test $REPLACE_MODF = 1; then
+    dnl Find libraries needed to link lib/modf.c.
+    AC_REQUIRE([gl_FUNC_TRUNC])
+    MODF_LIBM="$TRUNC_LIBM"
+  fi
 ])