1/* mpi-bit.c - MPI bit level fucntions 2 * Copyright (C) 1998, 1999 Free Software Foundation, Inc. 3 * 4 * This file is part of GnuPG. 5 * 6 * GnuPG is free software; you can redistribute it and/or modify 7 * it under the terms of the GNU General Public License as published by 8 * the Free Software Foundation; either version 2 of the License, or 9 * (at your option) any later version. 10 * 11 * GnuPG is distributed in the hope that it will be useful, 12 * but WITHOUT ANY WARRANTY; without even the implied warranty of 13 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 14 * GNU General Public License for more details. 15 * 16 * You should have received a copy of the GNU General Public License 17 * along with this program; if not, write to the Free Software 18 * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA 19 */ 20 21#include "mpi-internal.h" 22#include "longlong.h" 23 24#define A_LIMB_1 ((mpi_limb_t) 1) 25 26/**************** 27 * Sometimes we have MSL (most significant limbs) which are 0; 28 * this is for some reasons not good, so this function removes them. 29 */ 30void mpi_normalize(MPI a) 31{ 32 for (; a->nlimbs && !a->d[a->nlimbs - 1]; a->nlimbs--) 33 ; 34} 35 36/**************** 37 * Return the number of bits in A. 38 */ 39unsigned mpi_get_nbits(MPI a) 40{ 41 unsigned n; 42 43 mpi_normalize(a); 44 45 if (a->nlimbs) { 46 mpi_limb_t alimb = a->d[a->nlimbs - 1]; 47 if (alimb) 48 n = count_leading_zeros(alimb); 49 else 50 n = BITS_PER_MPI_LIMB; 51 n = BITS_PER_MPI_LIMB - n + (a->nlimbs - 1) * BITS_PER_MPI_LIMB; 52 } else 53 n = 0; 54 return n; 55} 56EXPORT_SYMBOL_GPL(mpi_get_nbits); 57