--- /dev/null
+/* mpfr_mul_2si -- multiply 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_mul_2si (mpfr_ptr y, mpfr_srcptr x, long int n, mp_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)) )
+ {
+ mp_exp_t exp = MPFR_GET_EXP (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));
+
+ else if (MPFR_UNLIKELY(n < 0 && (__gmpfr_emin > MPFR_EMAX_MAX + n ||
+ exp < __gmpfr_emin - n)))
+ {
+ if (rnd_mode == GMP_RNDN &&
+ (__gmpfr_emin > MPFR_EMAX_MAX + (n + 1) ||
+ exp < __gmpfr_emin - (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 + n);
+ }
+
+ return inexact;
+}