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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-lshift.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-lshift.c')
-rw-r--r--lib/crypto/mpi/generic_mpih-lshift.c50
1 files changed, 50 insertions, 0 deletions
diff --git a/lib/crypto/mpi/generic_mpih-lshift.c b/lib/crypto/mpi/generic_mpih-lshift.c
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index 000000000000..7b21f5938a50
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+++ b/lib/crypto/mpi/generic_mpih-lshift.c
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+// SPDX-License-Identifier: GPL-2.0-or-later
+/* mpihelp-lshift.c - MPI helper functions
+ * Copyright (C) 1994, 1996, 1998, 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 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.
+ */
+
+mpi_limb_t
+mpihelp_lshift(mpi_ptr_t wp, mpi_ptr_t up, mpi_size_t usize, unsigned int 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;
+ 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;
+}