From 2a598d0b2800aa23ba51adcf060cec524aaa63b2 Mon Sep 17 00:00:00 2001 From: Herbert Xu Date: Fri, 4 Aug 2023 17:24:34 +0800 Subject: crypto: lib - Move mpi into lib/crypto As lib/mpi is mostly used by crypto code, move it under lib/crypto so that patches touching it get directed to the right mailing list. Signed-off-by: Herbert Xu Reviewed-by: Mimi Zohar Signed-off-by: Herbert Xu --- lib/crypto/mpi/generic_mpih-lshift.c | 50 ++++++++++++++++++++++++++++++++++++ 1 file changed, 50 insertions(+) create mode 100644 lib/crypto/mpi/generic_mpih-lshift.c (limited to 'lib/crypto/mpi/generic_mpih-lshift.c') diff --git a/lib/crypto/mpi/generic_mpih-lshift.c b/lib/crypto/mpi/generic_mpih-lshift.c new file mode 100644 index 000000000000..7b21f5938a50 --- /dev/null +++ b/lib/crypto/mpi/generic_mpih-lshift.c @@ -0,0 +1,50 @@ +// 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; +} -- cgit v1.2.3