mirror of
https://github.com/torvalds/linux.git
synced 2024-12-21 02:21:36 +00:00
aacf29bf1b
Provide count_leading/trailing_zeros() macros based on extant arch bit scanning functions rather than reimplementing from scratch in MPILIB. Whilst we're at it, turn count_foo_zeros(n, x) into n = count_foo_zeros(x). Also move the definition to asm-generic as other people may be interested in using it. Signed-off-by: David Howells <dhowells@redhat.com> Cc: David S. Miller <davem@davemloft.net> Cc: Dmitry Kasatkin <dmitry.kasatkin@intel.com> Cc: Arnd Bergmann <arnd@arndb.com> Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
57 lines
1.5 KiB
C
57 lines
1.5 KiB
C
/* mpi-bit.c - MPI bit level fucntions
|
|
* Copyright (C) 1998, 1999 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
|
|
*/
|
|
|
|
#include "mpi-internal.h"
|
|
#include "longlong.h"
|
|
|
|
#define A_LIMB_1 ((mpi_limb_t) 1)
|
|
|
|
/****************
|
|
* Sometimes we have MSL (most significant limbs) which are 0;
|
|
* this is for some reasons not good, so this function removes them.
|
|
*/
|
|
void mpi_normalize(MPI a)
|
|
{
|
|
for (; a->nlimbs && !a->d[a->nlimbs - 1]; a->nlimbs--)
|
|
;
|
|
}
|
|
|
|
/****************
|
|
* Return the number of bits in A.
|
|
*/
|
|
unsigned mpi_get_nbits(MPI a)
|
|
{
|
|
unsigned n;
|
|
|
|
mpi_normalize(a);
|
|
|
|
if (a->nlimbs) {
|
|
mpi_limb_t alimb = a->d[a->nlimbs - 1];
|
|
if (alimb)
|
|
n = count_leading_zeros(alimb);
|
|
else
|
|
n = BITS_PER_MPI_LIMB;
|
|
n = BITS_PER_MPI_LIMB - n + (a->nlimbs - 1) * BITS_PER_MPI_LIMB;
|
|
} else
|
|
n = 0;
|
|
return n;
|
|
}
|
|
EXPORT_SYMBOL_GPL(mpi_get_nbits);
|