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author | James Morris <jmorris@namei.org> | 2012-01-09 05:16:48 +0400 |
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committer | James Morris <jmorris@namei.org> | 2012-01-09 05:16:48 +0400 |
commit | 8fcc99549522fc7a0bbaeb5755855ab0d9a59ce8 (patch) | |
tree | a118eaef15d4ba22247f45ee01537ecc906cd161 /lib/mpi/generic_mpih-rshift.c | |
parent | 805a6af8dba5dfdd35ec35dc52ec0122400b2610 (diff) | |
parent | 7b7e5916aa2f46e57f8bd8cb89c34620ebfda5da (diff) | |
download | linux-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')
-rw-r--r-- | lib/mpi/generic_mpih-rshift.c | 63 |
1 files changed, 63 insertions, 0 deletions
diff --git a/lib/mpi/generic_mpih-rshift.c b/lib/mpi/generic_mpih-rshift.c new file mode 100644 index 000000000000..ffa328818ca6 --- /dev/null +++ b/lib/mpi/generic_mpih-rshift.c @@ -0,0 +1,63 @@ +/* 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; +} |