[project @ 1996-01-08 20:28:12 by partain]

Initial revision

1 files changed, 86 insertions, 0 deletions

diff --git a/ghc/runtime/gmp/mpn_rshiftci.c b/ghc/runtime/gmp/mpn_rshiftci.c
new file mode 100644
index 0000000000..b072d02a90
--- /dev/null
+++ b/ghc/runtime/gmp/mpn_rshiftci.c
@@ -0,0 +1,86 @@
+/* mpn_rshiftci -- Shift a low level natural-number integer with carry in.
+
+Copyright (C) 1991 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 General Public License as published by
+the Free Software Foundation; either version 2, 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 General Public License for more details.
+
+You should have received a copy of the GNU General Public License
+along with the GNU MP Library; see the file COPYING.  If not, write to
+the Free Software Foundation, 675 Mass Ave, Cambridge, MA 02139, USA.  */
+
+#include "gmp.h"
+#include "gmp-impl.h"
+
+/* Shift U (pointed to by UP and USIZE digits long) CNT bits to the right
+   and store the USIZE least significant digits of the result at WP.
+   Return the size of the result.
+
+   Argument constraints:
+   0. U must be normalized (i.e. it's most significant digit != 0).
+   1. 0 <= CNT < BITS_PER_MP_LIMB
+   2. If the result is to be written over the input, WP must be <= UP.
+*/
+
+mp_size
+#ifdef __STDC__
+mpn_rshiftci (mp_ptr wp,
+	       mp_srcptr up, mp_size usize,
+	       unsigned cnt,
+	       mp_limb carry_in)
+#else
+mpn_rshiftci (wp, up, usize, cnt, carry_in)
+     mp_ptr wp;
+     mp_srcptr up;
+     mp_size usize;
+     unsigned cnt;
+     mp_limb carry_in;
+#endif
+{
+  mp_limb high_limb, low_limb;
+  unsigned sh_1, sh_2;
+  mp_size i;
+
+  if (usize <= 0)
+    return 0;
+
+  sh_1 = cnt;
+  if (sh_1 == 0)
+    {
+      if (wp != up)
+	{
+	  /* Copy from low end to high end, to allow specified input/output
+	     overlapping.  */
+	  for (i = 0; i < usize; i++)
+	    wp[i] = up[i];
+	}
+      return usize;
+    }
+
+  wp -= 1;
+  sh_2 = BITS_PER_MP_LIMB - sh_1;
+  low_limb = up[0];
+  for (i = 1; i < usize; i++)
+    {
+      high_limb = up[i];
+      wp[i] = (low_limb >> sh_1) | (high_limb << sh_2);
+      low_limb = high_limb;
+    }
+  low_limb = (low_limb >> sh_1) | (carry_in << sh_2);
+  if (low_limb != 0)
+    {
+      wp[i] = low_limb;
+      return usize;
+    }
+
+  return usize - 1;
+}