1 files changed, 57 insertions, 0 deletions
diff --git a/src/div_2si.c b/src/div_2si.c
new file mode 100644
index 000000000..2837924a2
--- /dev/null
+++ b/src/div_2si.c
@@ -0,0 +1,57 @@
+/* mpfr_div_2si -- divide a floating-point number by a power of two
+
+Copyright 1999, 2001, 2002, 2003, 2004, 2005, 2006, 2007, 2008, 2009, 2010 Free Software Foundation, Inc.
+Contributed by the Arenaire 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_2si (mpfr_ptr y, mpfr_srcptr x, long int n, mpfr_rnd_t rnd_mode)
+{
+  int inexact;
+
+  MPFR_LOG_FUNC (("x[%#R]=%R n=%ld rnd=%d", x, x, n, rnd_mode),
+                 ("y[%#R]=%R inexact=%d", y, y, inexact));
+
+  inexact = MPFR_UNLIKELY(y != x) ? mpfr_set (y, x, rnd_mode) : 0;
+
+  if (MPFR_LIKELY( MPFR_IS_PURE_FP(y) ))
+    {
+      mpfr_exp_t exp = MPFR_GET_EXP (y);
+      if (MPFR_UNLIKELY( n > 0 && (__gmpfr_emin > MPFR_EMAX_MAX - n ||
+                                   exp < __gmpfr_emin + n)) )
+        {
+          if (rnd_mode == MPFR_RNDN &&
+              (__gmpfr_emin > MPFR_EMAX_MAX - (n - 1) ||
+               exp < __gmpfr_emin + (n - 1) ||
+               (inexact >= 0 && mpfr_powerof2_raw (y))))
+            rnd_mode = MPFR_RNDZ;
+          return mpfr_underflow (y, rnd_mode, MPFR_SIGN(y));
+        }
+
+      if (MPFR_UNLIKELY(n < 0 && (__gmpfr_emax < MPFR_EMIN_MIN - n ||
+                                  exp > __gmpfr_emax + n)) )
+        return mpfr_overflow (y, rnd_mode, MPFR_SIGN(y));
+
+      MPFR_SET_EXP (y, exp - n);
+    }
+
+  return inexact;
+}