Functions mpfr_{mul,div}_2{si,ui} added.

Functions mpfr_{mul,div}_2exp still exist for backward compatibility;
they are obsolete and should not be used any longer.


git-svn-id: svn://scm.gforge.inria.fr/svn/mpfr/trunk@1587 280ebfd0-de03-0410-8827-d642c229c3f4

1 files changed, 59 insertions, 0 deletions

diff --git a/mul_2ui.c b/mul_2ui.c
new file mode 100644
index 000000000..64ac7c7ae
--- /dev/null
+++ b/mul_2ui.c
@@ -0,0 +1,59 @@
+/* mpfr_mul_2ui -- multiply a floating-point number by a power of two
+
+Copyright (C) 1999, 2001 Free Software Foundation, Inc.
+
+This file is part of the MPFR Library.
+
+The 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 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 MPFR Library; see the file COPYING.LIB.  If not, write to
+the Free Software Foundation, Inc., 59 Temple Place - Suite 330, Boston,
+MA 02111-1307, USA. */
+
+#include "gmp.h"
+#include "gmp-impl.h"
+#include "mpfr.h"
+#include "mpfr-impl.h"
+
+int
+mpfr_mul_2ui (mpfr_ptr y, mpfr_srcptr x, unsigned long int n, mp_rnd_t rnd_mode)
+{
+  int inexact;
+
+  inexact = y != x ? mpfr_set (y, x, rnd_mode) : 0;
+
+  if (MPFR_IS_FP(y) && MPFR_NOTZERO(y))
+    {
+      /* n will have to be casted to long to make sure that the addition
+         and subtraction below (for overflow detection) are signed */
+      while (n > LONG_MAX)
+        {
+          int inex2;
+
+          n -= LONG_MAX;
+          inex2 = mpfr_mul_2ui(y, y, LONG_MAX, rnd_mode);
+          if (inex2)
+            return inex2; /* overflow */
+        }
+
+      /* MPFR_EMIN_MIN + (long) n is signed and doesn't lead to an overflow;
+         the first test useful so that the real test can't lead to an
+         overflow. */
+      if (__mpfr_emax < MPFR_EMIN_MIN + (long) n ||
+          MPFR_EXP(y) > __mpfr_emax - (long) n)
+        return mpfr_set_overflow (y, rnd_mode, MPFR_SIGN(y));
+
+      MPFR_EXP(y) += (long) n;
+    }
+
+  return inexact;
+}