add implementations from glibc for the round functions

1 files changed, 92 insertions, 0 deletions

diff --git a/libm/s_round.c b/libm/s_round.c
new file mode 100644
index 000000000..b2d009520
--- /dev/null
+++ b/libm/s_round.c
@@ -0,0 +1,92 @@
+/* Round double to integer away from zero.
+   Copyright (C) 1997 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+   Contributed by Ulrich Drepper <drepper@cygnus.com>, 1997.
+
+   The GNU C Library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Lesser General Public
+   License as published by the Free Software Foundation; either
+   version 2.1 of the License, or (at your option) any later version.
+
+   The GNU C Library is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public
+   License along with the GNU C Library; if not, write to the Free
+   Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
+   02111-1307 USA.  */
+
+#include <math.h>
+
+#include "math_private.h"
+
+
+static const double huge = 1.0e300;
+
+
+double
+round (double x)
+{
+  int32_t i0, j0;
+  u_int32_t i1;
+
+  EXTRACT_WORDS (i0, i1, x);
+  j0 = ((i0 >> 20) & 0x7ff) - 0x3ff;
+  if (j0 < 20)
+    {
+      if (j0 < 0)
+	{
+	  if (huge + x > 0.0)
+	    {
+	      i0 &= 0x80000000;
+	      if (j0 == -1)
+		i0 |= 0x3ff00000;
+	      i1 = 0;
+	    }
+	}
+      else
+	{
+	  u_int32_t i = 0x000fffff >> j0;
+	  if (((i0 & i) | i1) == 0)
+	    /* X is integral.  */
+	    return x;
+	  if (huge + x > 0.0)
+	    {
+	      /* Raise inexact if x != 0.  */
+	      i0 += 0x00080000 >> j0;
+	      i0 &= ~i;
+	      i1 = 0;
+	    }
+	}
+    }
+  else if (j0 > 51)
+    {
+      if (j0 == 0x400)
+	/* Inf or NaN.  */
+	return x + x;
+      else
+	return x;
+    }
+  else
+    {
+      u_int32_t i = 0xffffffff >> (j0 - 20);
+      if ((i1 & i) == 0)
+	/* X is integral.  */
+	return x;
+
+      if (huge + x > 0.0)
+	{
+	  /* Raise inexact if x != 0.  */
+	  u_int32_t j = i1 + (1 << (51 - j0));
+	  if (j < i1)
+	    i0 += 1;
+	  i1 = j;
+	}
+      i1 &= ~i;
+    }
+
+  INSERT_WORDS (x, i0, i1);
+  return x;
+}