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authorThomas Zimmermann <[email protected]>2023-10-11 09:50:59 +0200
committerThomas Zimmermann <[email protected]>2023-10-11 09:50:59 +0200
commit57390019b68b83f96eb98f490367b9df1f2d77cb (patch)
treee6d4b6c75efdd2d7fb7d37f980688c491be3ff6a /lib/crypto/mpi/generic_mpih-rshift.c
parente5f9d543419c78ac58f3b3557bc5a76b20ff600b (diff)
parent389af786f92ecdff35883551d54bf4e507ffcccb (diff)
Merge drm/drm-next into drm-misc-next
Updating drm-misc-next to the state of Linux v6.6-rc2. Signed-off-by: Thomas Zimmermann <[email protected]>
Diffstat (limited to 'lib/crypto/mpi/generic_mpih-rshift.c')
-rw-r--r--lib/crypto/mpi/generic_mpih-rshift.c50
1 files changed, 50 insertions, 0 deletions
diff --git a/lib/crypto/mpi/generic_mpih-rshift.c b/lib/crypto/mpi/generic_mpih-rshift.c
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+++ b/lib/crypto/mpi/generic_mpih-rshift.c
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+// SPDX-License-Identifier: GPL-2.0-or-later
+/* mpih-rshift.c - MPI helper functions
+ * Copyright (C) 1994, 1996, 1998, 1999,
+ * 2000, 2001 Free Software Foundation, Inc.
+ *
+ * This file is part of GNUPG
+ *
+ * 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;
+}