linux/lib/mpi/generic_mpih-rshift.c
Thomas Gleixner 465ae83692 treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 26
Based on 1 normalized pattern(s):

  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

extracted by the scancode license scanner the SPDX license identifier

  GPL-2.0-or-later

has been chosen to replace the boilerplate/reference in 14 file(s).

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Allison Randal <allison@lohutok.net>
Reviewed-by: Kate Stewart <kstewart@linuxfoundation.org>
Cc: linux-spdx@vger.kernel.org
Link: https://lkml.kernel.org/r/20190520170856.639982569@linutronix.de
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2019-05-24 17:27:10 +02:00

51 lines
1.5 KiB
C

// 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;
}