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authorJames Morris <jmorris@namei.org>2012-01-09 05:16:48 +0400
committerJames Morris <jmorris@namei.org>2012-01-09 05:16:48 +0400
commit8fcc99549522fc7a0bbaeb5755855ab0d9a59ce8 (patch)
treea118eaef15d4ba22247f45ee01537ecc906cd161 /lib/mpi/generic_mpih-rshift.c
parent805a6af8dba5dfdd35ec35dc52ec0122400b2610 (diff)
parent7b7e5916aa2f46e57f8bd8cb89c34620ebfda5da (diff)
downloadlinux-8fcc99549522fc7a0bbaeb5755855ab0d9a59ce8.tar.xz
Merge branch 'next' into for-linus
Conflicts: security/integrity/evm/evm_crypto.c Resolved upstream fix vs. next conflict manually. Signed-off-by: James Morris <jmorris@namei.org>
Diffstat (limited to 'lib/mpi/generic_mpih-rshift.c')
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diff --git a/lib/mpi/generic_mpih-rshift.c b/lib/mpi/generic_mpih-rshift.c
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+/* mpih-rshift.c - MPI helper functions
+ * Copyright (C) 1994, 1996, 1998, 1999,
+ * 2000, 2001 Free Software Foundation, Inc.
+ *
+ * This file is part of GNUPG
+ *
+ * GNUPG 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 of the License, or
+ * (at your option) any later version.
+ *
+ * GNUPG 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 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.
+ * The GNU MP Library itself is published under the LGPL;
+ * however I decided to publish this code under the plain GPL.
+ */
+
+#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
+mpihelp_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;
+}