1 files changed, 67 insertions, 0 deletions
diff --git a/grub-core/lib/libgcrypt-grub/mpi/mpih-rshift.c b/grub-core/lib/libgcrypt-grub/mpi/mpih-rshift.c
new file mode 100644
index 0000000..e40794f
--- /dev/null
+++ b/grub-core/lib/libgcrypt-grub/mpi/mpih-rshift.c
@@ -0,0 +1,67 @@
+/* mpih-rshift.c  -  MPI helper functions
+ * Copyright (C) 1994, 1996, 1998, 1999,
+ *               2000, 2001, 2002 Free Software Foundation, Inc.
+ *
+ * This file is part of Libgcrypt.
+ *
+ * Libgcrypt 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.
+ *
+ * Libgcrypt 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 this program; if not, write to the Free Software
+ * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA
+ *
+ * Note: This code is heavily based on the GNU MP Library.
+ *	 Actually it's the same code with only minor changes in the
+ *	 way the data is stored; this is to support the abstraction
+ *	 of an optional secure memory allocation which may be used
+ *	 to avoid revealing of sensitive data due to paging etc.
+ */
+
+#include <config.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include "mpi-internal.h"
+
+
+/* Shift U (pointed to by UP and USIZE limbs long) CNT bits to the right
+ * and store the USIZE least significant limbs of the result at WP.
+ * The bits shifted out to the right are returned.
+ *
+ * Argument constraints:
+ * 1. 0 < CNT < BITS_PER_MP_LIMB
+ * 2. If the result is to be written over the input, WP must be <= UP.
+ */
+
+mpi_limb_t
+_gcry_mpih_rshift( mpi_ptr_t wp, mpi_ptr_t up, mpi_size_t usize, unsigned cnt)
+{
+  mpi_limb_t high_limb, low_limb;
+  unsigned sh_1, sh_2;
+  mpi_size_t i;
+  mpi_limb_t retval;
+
+  sh_1 = cnt;
+  wp -= 1;
+  sh_2 = BITS_PER_MPI_LIMB - sh_1;
+  high_limb = up[0];
+  retval = high_limb << sh_2;
+  low_limb = high_limb;
+  for (i=1; i < usize; i++)
+    {
+      high_limb = up[i];
+      wp[i] = (low_limb >> sh_1) | (high_limb << sh_2);
+      low_limb = high_limb;
+    }
+  wp[i] = low_limb >> sh_1;
+
+  return retval;
+}
+