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>
56 lines
1.5 KiB
C
56 lines
1.5 KiB
C
/* mpi-bit.c - MPI bit level fucntions
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* Copyright (C) 1998, 1999 Free Software Foundation, Inc.
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*
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* This file is part of GnuPG.
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*
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* GnuPG is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; either version 2 of the License, or
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* (at your option) any later version.
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*
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* GnuPG is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program; if not, write to the Free Software
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* Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA
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*/
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#include "mpi-internal.h"
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#include "longlong.h"
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#define A_LIMB_1 ((mpi_limb_t) 1)
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/****************
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* Sometimes we have MSL (most significant limbs) which are 0;
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* this is for some reasons not good, so this function removes them.
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*/
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void mpi_normalize(MPI a)
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{
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for (; a->nlimbs && !a->d[a->nlimbs - 1]; a->nlimbs--)
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;
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}
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/****************
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* Return the number of bits in A.
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*/
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unsigned mpi_get_nbits(MPI a)
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{
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unsigned n;
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mpi_normalize(a);
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if (a->nlimbs) {
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mpi_limb_t alimb = a->d[a->nlimbs - 1];
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if (alimb)
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n = count_leading_zeros(alimb);
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else
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n = BITS_PER_MPI_LIMB;
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n = BITS_PER_MPI_LIMB - n + (a->nlimbs - 1) * BITS_PER_MPI_LIMB;
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} else
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n = 0;
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return n;
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}
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EXPORT_SYMBOL_GPL(mpi_get_nbits);
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