Branch data Line data Source code
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 : : */ 30 : 84 : void mpi_normalize(MPI a) 31 : : { 32 [ - - - - : 84 : for (; a->nlimbs && !a->d[a->nlimbs - 1]; a->nlimbs--) + - - + ] 33 : 0 : ; 34 : 84 : } 35 : : 36 : : /**************** 37 : : * Return the number of bits in A. 38 : : */ 39 : 0 : unsigned mpi_get_nbits(MPI a) 40 : : { 41 : 0 : unsigned n; 42 : : 43 : 0 : mpi_normalize(a); 44 : : 45 [ # # ]: 0 : if (a->nlimbs) { 46 : 0 : mpi_limb_t alimb = a->d[a->nlimbs - 1]; 47 [ # # ]: 0 : if (alimb) 48 : 0 : n = count_leading_zeros(alimb); 49 : : else 50 : : n = BITS_PER_MPI_LIMB; 51 : 0 : n = BITS_PER_MPI_LIMB - n + (a->nlimbs - 1) * BITS_PER_MPI_LIMB; 52 : : } else 53 : : n = 0; 54 : 0 : return n; 55 : : } 56 : : EXPORT_SYMBOL_GPL(mpi_get_nbits);