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
  23 int 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 }
  42 EXPORT_SYMBOL_GPL(mpi_cmp_ui);
  43
  44 static 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
  84 int mpi_cmp(MPI u, MPI v)
  85 {
  86         return do_mpi_cmp(u, v, 0);
  87 }
  88 EXPORT_SYMBOL_GPL(mpi_cmp);
  89
  90 int mpi_cmpabs(MPI u, MPI v)
  91 {
  92         return do_mpi_cmp(u, v, 1);
  93 }
  94 EXPORT_SYMBOL_GPL(mpi_cmpabs);