1 files changed, 73 insertions, 0 deletions
diff --git a/src/set_si_2exp.c b/src/set_si_2exp.c
new file mode 100644
index 0000000..2064a70
--- /dev/null
+++ b/src/set_si_2exp.c
@@ -0,0 +1,73 @@
+/* mpfr_set_si_2exp -- set a MPFR number from a machine signed integer with
+   a shift
+
+Copyright 2004, 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. */
+
+#define MPFR_NEED_LONGLONG_H
+#include "mpfr-impl.h"
+
+int
+mpfr_set_si_2exp (mpfr_ptr x, long i, mpfr_exp_t e, mpfr_rnd_t rnd_mode)
+{
+  if (i == 0)
+    {
+      MPFR_SET_ZERO (x);
+      MPFR_SET_POS (x);
+      MPFR_RET (0);
+    }
+  else
+    {
+      mp_size_t xn;
+      unsigned int cnt, nbits;
+      mp_limb_t ai, *xp;
+      int inex = 0;
+
+      /* FIXME: support int limbs (e.g. 16-bit limbs on 16-bit proc) */
+      ai = SAFE_ABS (unsigned long, i);
+      MPFR_ASSERTN (SAFE_ABS (unsigned long, i) == ai);
+
+      /* Position of the highest limb */
+      xn = (MPFR_PREC (x) - 1) / GMP_NUMB_BITS;
+      count_leading_zeros (cnt, ai);
+      MPFR_ASSERTD (cnt < GMP_NUMB_BITS);  /* OK since i != 0 */
+
+      xp = MPFR_MANT(x);
+      xp[xn] = ai << cnt;
+      /* Zero the xn lower limbs. */
+      MPN_ZERO(xp, xn);
+      MPFR_SET_SIGN (x, i < 0 ? MPFR_SIGN_NEG : MPFR_SIGN_POS);
+
+      nbits = GMP_NUMB_BITS - cnt;
+      e += nbits;  /* exponent _before_ the rounding */
+
+      /* round if MPFR_PREC(x) smaller than length of i */
+      if (MPFR_UNLIKELY (MPFR_PREC (x) < nbits) &&
+          MPFR_UNLIKELY (mpfr_round_raw (xp + xn, xp + xn, nbits, i < 0,
+                                         MPFR_PREC (x), rnd_mode, &inex)))
+        {
+          e++;
+          xp[xn] = MPFR_LIMB_HIGHBIT;
+        }
+
+      MPFR_EXP (x) = e;
+      return mpfr_check_range (x, inex, rnd_mode);
+    }
+}