2.5-18.1

1 files changed, 87 insertions, 0 deletions

diff --git a/stdlib/lshift.c b/stdlib/lshift.c
new file mode 100644
index 0000000000..bedf44229f
--- /dev/null
+++ b/stdlib/lshift.c
@@ -0,0 +1,87 @@
+/* mpn_lshift -- Shift left low level.
+
+Copyright (C) 1991, 1993, 1994, 1996 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 2.1 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; 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"
+
+/* Shift U (pointed to by UP and USIZE digits long) CNT bits to the left
+   and store the USIZE least significant digits of the result at WP.
+   Return the bits shifted out from the most significant digit.
+
+   Argument constraints:
+   1. 0 < CNT < BITS_PER_MP_LIMB
+   2. If the result is to be written over the input, WP must be >= UP.
+*/
+
+mp_limb_t
+#if __STDC__
+mpn_lshift (register mp_ptr wp,
+	    register mp_srcptr up, mp_size_t usize,
+	    register unsigned int cnt)
+#else
+mpn_lshift (wp, up, usize, cnt)
+     register mp_ptr wp;
+     register mp_srcptr up;
+     mp_size_t usize;
+     register unsigned int cnt;
+#endif
+{
+  register mp_limb_t high_limb, low_limb;
+  register unsigned sh_1, sh_2;
+  register mp_size_t i;
+  mp_limb_t retval;
+
+#ifdef DEBUG
+  if (usize == 0 || cnt == 0)
+    abort ();
+#endif
+
+  sh_1 = cnt;
+#if 0
+  if (sh_1 == 0)
+    {
+      if (wp != up)
+	{
+	  /* Copy from high end to low end, to allow specified input/output
+	     overlapping.  */
+	  for (i = usize - 1; i >= 0; i--)
+	    wp[i] = up[i];
+	}
+      return 0;
+    }
+#endif
+
+  wp += 1;
+  sh_2 = BITS_PER_MP_LIMB - sh_1;
+  i = usize - 1;
+  low_limb = up[i];
+  retval = low_limb >> sh_2;
+  high_limb = low_limb;
+  while (--i >= 0)
+    {
+      low_limb = up[i];
+      wp[i] = (high_limb << sh_1) | (low_limb >> sh_2);
+      high_limb = low_limb;
+    }
+  wp[i] = high_limb << sh_1;
+
+  return retval;
+}