1 files changed, 61 insertions, 0 deletions
diff --git a/mpfr/src/div_2ui.c b/mpfr/src/div_2ui.c
new file mode 100644
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+++ b/mpfr/src/div_2ui.c
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+/* mpfr_div_2ui -- divide a floating-point number by a power of two
+
+Copyright 1999, 2001, 2002, 2003, 2004, 2005, 2006, 2007, 2008, 2009, 2010, 2011, 2012, 2013 Free Software Foundation, Inc.
+Contributed by the AriC and Caramel projects, INRIA.
+
+This file is part of the GNU MPFR Library.
+
+The GNU MPFR 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 3 of the License, or (at your
+option) any later version.
+
+The GNU MPFR 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 MPFR Library; see the file COPYING.LESSER.  If not, see
+http://www.gnu.org/licenses/ or write to the Free Software Foundation, Inc.,
+51 Franklin St, Fifth Floor, Boston, MA 02110-1301, USA. */
+
+#include "mpfr-impl.h"
+
+int
+mpfr_div_2ui (mpfr_ptr y, mpfr_srcptr x, unsigned long n, mpfr_rnd_t rnd_mode)
+{
+  int inexact;
+
+  MPFR_LOG_FUNC (
+    ("x[%Pu]=%.*Rg n=%lu rnd=%d", mpfr_get_prec(x), mpfr_log_prec, x, n,
+     rnd_mode),
+    ("y[%Pu]=%.*Rg inexact=%d", mpfr_get_prec(y), mpfr_log_prec, y, inexact));
+
+  if (MPFR_UNLIKELY (MPFR_IS_SINGULAR (x)))
+    return mpfr_set (y, x, rnd_mode);
+  else
+    {
+      mpfr_exp_t exp = MPFR_GET_EXP (x);
+      mpfr_uexp_t diffexp;
+
+      MPFR_SETRAW (inexact, y, x, exp, rnd_mode);
+      diffexp = (mpfr_uexp_t) exp - (mpfr_uexp_t) (__gmpfr_emin - 1);
+      if (MPFR_UNLIKELY (n >= diffexp))  /* exp - n <= emin - 1 */
+        {
+          if (rnd_mode == MPFR_RNDN &&
+              (n > diffexp || (inexact >= 0 && mpfr_powerof2_raw (y))))
+            rnd_mode = MPFR_RNDZ;
+          return mpfr_underflow (y, rnd_mode, MPFR_SIGN (y));
+        }
+      /* exp - n >= emin (no underflow, no integer overflow) */
+      while (n > LONG_MAX)
+        {
+          n -= LONG_MAX;
+          exp -= LONG_MAX;  /* note: signed values */
+        }
+      MPFR_SET_EXP (y, exp - (long) n);
+    }
+
+  MPFR_RET (inexact);
+}