LXR linux/lib/mpi/mpi-cmp.c

   1/* mpi-cmp.c  -  MPI functions
   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
  23int mpi_cmp_ui(MPI u, unsigned long v)
  24{
  25        mpi_limb_t limb = v;
  26
  27        mpi_normalize(u);
  28        if (!u->nlimbs && !limb)
  29                return 0;
  30        if (u->sign)
  31                return -1;
  32        if (u->nlimbs > 1)
  33                return 1;
  34
  35        if (u->d[0] == limb)
  36                return 0;
  37        else if (u->d[0] > limb)
  38                return 1;
  39        else
  40                return -1;
  41}
  42EXPORT_SYMBOL_GPL(mpi_cmp_ui);
  43
  44static int do_mpi_cmp(MPI u, MPI v, int absmode)
  45{
  46        mpi_size_t usize;
  47        mpi_size_t vsize;
  48        int usign;
  49        int vsign;
  50        int cmp;
  51
  52        mpi_normalize(u);
  53        mpi_normalize(v);
  54
  55        usize = u->nlimbs;
  56        vsize = v->nlimbs;
  57        usign = absmode ? 0 : u->sign;
  58        vsign = absmode ? 0 : v->sign;
  59
  60        /* Compare sign bits.  */
  61
  62        if (!usign && vsign)
  63                return 1;
  64        if (usign && !vsign)
  65                return -1;
  66
  67        /* U and V are either both positive or both negative.  */
  68
  69        if (usize != vsize && !usign && !vsign)
  70                return usize - vsize;
  71        if (usize != vsize && usign && vsign)
  72                return vsize + usize;
  73        if (!usize)
  74                return 0;
  75        cmp = mpihelp_cmp(u->d, v->d, usize);
  76        if (!cmp)
  77                return 0;
  78        if ((cmp < 0?1:0) == (usign?1:0))
  79                return 1;
  80
  81        return -1;
  82}
  83
  84int mpi_cmp(MPI u, MPI v)
  85{
  86        return do_mpi_cmp(u, v, 0);
  87}
  88EXPORT_SYMBOL_GPL(mpi_cmp);
  89
  90int mpi_cmpabs(MPI u, MPI v)
  91{
  92        return do_mpi_cmp(u, v, 1);
  93}
  94EXPORT_SYMBOL_GPL(mpi_cmpabs);
  95