mpi-genesis 1
mpi_second_cut 2 * Modified by No Such Labs. (C) 2015. See README.
mpi-genesis 3 *
mpi_second_cut 4 * This file was originally part of Gnu Privacy Guard (GPG), ver. 1.4.10,
mpi_second_cut 5 * SHA256(gnupg-1.4.10.tar.gz):
mpi_second_cut 6 * 0bfd74660a2f6cedcf7d8256db4a63c996ffebbcdc2cf54397bfb72878c5a85a
mpi_second_cut 7 * (C) 1994-2005 Free Software Foundation, Inc.
mpi-genesis 8 *
mpi_second_cut 9 * This program is free software: you can redistribute it and/or modify
mpi-genesis 10 * it under the terms of the GNU General Public License as published by
mpi_second_cut 11 * the Free Software Foundation, either version 3 of the License, or
mpi-genesis 12 * (at your option) any later version.
mpi-genesis 13 *
mpi_second_cut 14 * This program is distributed in the hope that it will be useful,
mpi-genesis 15 * but WITHOUT ANY WARRANTY; without even the implied warranty of
mpi-genesis 16 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
mpi-genesis 17 * GNU General Public License for more details.
mpi-genesis 18 *
mpi-genesis 19 * You should have received a copy of the GNU General Public License
mpi_second_cut 20 * along with this program. If not, see <http:
mpi-genesis 21 */
mpi-genesis 22
mpi-genesis 23 #include <stdio.h>
mpi-genesis 24 #include <stdlib.h>
mpi_second_cut 25
mpi_second_cut 26 #include "knobs.h"
mpi-genesis 27 #include "mpi-internal.h"
mpi-genesis 28
mpi-genesis 29
mpi-genesis 30
mpi-genesis 31 * and store the USIZE least significant limbs of the result at WP.
mpi-genesis 32 * The bits shifted out to the right are returned.
mpi-genesis 33 *
mpi-genesis 34 * Argument constraints:
mpi-genesis 35 * 1. 0 < CNT < BITS_PER_MP_LIMB
mpi-genesis 36 * 2. If the result is to be written over the input, WP must be <= UP.
mpi-genesis 37 */
mpi-genesis 38
mpi-genesis 39 mpi_limb_t
mpi-genesis 40 mpihelp_rshift( mpi_ptr_t wp, mpi_ptr_t up, mpi_size_t usize, unsigned cnt)
mpi-genesis 41 {
mpi-genesis 42 mpi_limb_t high_limb, low_limb;
mpi-genesis 43 unsigned sh_1, sh_2;
mpi-genesis 44 mpi_size_t i;
mpi-genesis 45 mpi_limb_t retval;
mpi-genesis 46
mpi-genesis 47 sh_1 = cnt;
mpi-genesis 48 wp -= 1;
mpi-genesis 49 sh_2 = BITS_PER_MPI_LIMB - sh_1;
mpi-genesis 50 high_limb = up[0];
mpi-genesis 51 retval = high_limb << sh_2;
mpi-genesis 52 low_limb = high_limb;
mpi-genesis 53 for( i=1; i < usize; i++) {
mpi-genesis 54 high_limb = up[i];
mpi-genesis 55 wp[i] = (low_limb >> sh_1) | (high_limb << sh_2);
mpi-genesis 56 low_limb = high_limb;
mpi-genesis 57 }
mpi-genesis 58 wp[i] = low_limb >> sh_1;
mpi-genesis 59
mpi-genesis 60 return retval;
mpi-genesis 61 }
mpi-genesis 62