Imported gcc-4.4.3

[msp430-gcc.git] / mpfr / div_2ui.c

diff --git a/mpfr/div_2ui.c b/mpfr/div_2ui.c
new file mode 100644 (file)
index 0000000..3e91865
--- /dev/null
+++ b/mpfr/div_2ui.c
@@ -0,0 +1,71 @@
+/* mpfr_div_2ui -- divide a floating-point number by a power of two
+
+Copyright 1999, 2001, 2002, 2003, 2004, 2005, 2006, 2007, 2008, 2009 Free Software Foundation, Inc.
+Contributed by the Arenaire and Cacao 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 2.1 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.LIB.  If not, 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, mp_rnd_t rnd_mode)
+{
+  int inexact;
+
+  MPFR_LOG_FUNC (("x[%#R]=%R n=%lu rnd=%d", x, x, n, rnd_mode),
+                 ("y[%#R]=%R inexact=%d", y, y, inexact));
+
+  /* Most of the times, this function is called with y==x */
+  inexact = MPFR_UNLIKELY(y != x) ? mpfr_set (y, x, rnd_mode) : 0;
+
+  if (MPFR_LIKELY( MPFR_IS_PURE_FP(y)) )
+    {
+      /* n will have to be casted to long to make sure that the addition
+         and subtraction below (for overflow detection) are signed */
+      while (MPFR_UNLIKELY(n > LONG_MAX))
+        {
+          int inex2;
+
+          n -= LONG_MAX;
+          inex2 = mpfr_div_2ui(y, y, LONG_MAX, rnd_mode);
+          if (inex2)
+            return inex2; /* underflow */
+        }
+
+      /* MPFR_EMAX_MAX - (long) n is signed and doesn't lead to an integer
+         overflow; the first test useful so that the real test can't lead
+         to an integer overflow. */
+      {
+        mp_exp_t exp = MPFR_GET_EXP (y);
+        if (MPFR_UNLIKELY( __gmpfr_emin > MPFR_EMAX_MAX - (long) n ||
+                           exp < __gmpfr_emin + (long) n) )
+          {
+            if (rnd_mode == GMP_RNDN &&
+                (__gmpfr_emin > MPFR_EMAX_MAX - (long) (n - 1) ||
+                 exp < __gmpfr_emin + (long) (n - 1) ||
+                 (inexact >= 0 && mpfr_powerof2_raw (y))))
+              rnd_mode = GMP_RNDZ;
+            return mpfr_underflow (y, rnd_mode, MPFR_SIGN(y));
+          }
+
+        MPFR_SET_EXP(y, exp - (long) n);
+      }
+    }
+
+  return inexact;
+}