Imported gcc-4.4.3

[msp430-gcc.git] / gmp / mpn / generic / lshift.c

diff --git a/gmp/mpn/generic/lshift.c b/gmp/mpn/generic/lshift.c
new file mode 100644 (file)
index 0000000..fdc7e44
--- /dev/null
+++ b/gmp/mpn/generic/lshift.c
@@ -0,0 +1,63 @@
+/* mpn_lshift -- Shift left low level.
+
+Copyright 1991, 1993, 1994, 1996, 2000, 2001, 2002 Free Software Foundation,
+Inc.
+
+This file is part of the GNU MP Library.
+
+The GNU MP 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 MP 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 MP Library.  If not, see http://www.gnu.org/licenses/.  */
+
+#include "gmp.h"
+#include "gmp-impl.h"
+
+/* Shift U (pointed to by up and n limbs long) cnt bits to the left
+   and store the n least significant limbs of the result at rp.
+   Return the bits shifted out from the most significant limb.
+
+   Argument constraints:
+   1. 0 < cnt < GMP_NUMB_BITS.
+   2. If the result is to be written over the input, rp must be >= up.
+*/
+
+mp_limb_t
+mpn_lshift (mp_ptr rp, mp_srcptr up, mp_size_t n, unsigned int cnt)
+{
+  mp_limb_t high_limb, low_limb;
+  unsigned int tnc;
+  mp_size_t i;
+  mp_limb_t retval;
+
+  ASSERT (n >= 1);
+  ASSERT (cnt >= 1);
+  ASSERT (cnt < GMP_NUMB_BITS);
+  ASSERT (MPN_SAME_OR_DECR_P (rp, up, n));
+
+  up += n;
+  rp += n;
+
+  tnc = GMP_NUMB_BITS - cnt;
+  low_limb = *--up;
+  retval = low_limb >> tnc;
+  high_limb = (low_limb << cnt) & GMP_NUMB_MASK;
+
+  for (i = n - 1; i != 0; i--)
+    {
+      low_limb = *--up;
+      *--rp = high_limb | (low_limb >> tnc);
+      high_limb = (low_limb << cnt) & GMP_NUMB_MASK;
+    }
+  *--rp = high_limb;
+
+  return retval;
+}