contrib/gmp/mpf/cmp.c

   1 /* mpf_cmp -- Compare two floats.
   2
   3 Copyright 1993, 1994, 1996, 2001 Free Software Foundation, Inc.
   4
   5 This file is part of the GNU MP Library.
   6
   7 The GNU MP Library is free software; you can redistribute it and/or modify
   8 it under the terms of the GNU Lesser General Public License as published by
   9 the Free Software Foundation; either version 3 of the License, or (at your
  10 option) any later version.
  11
  12 The GNU MP Library is distributed in the hope that it will be useful, but
  13 WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
  14 or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU Lesser General Public
  15 License for more details.
  16
  17 You should have received a copy of the GNU Lesser General Public License
  18 along with the GNU MP Library.  If not, see http://www.gnu.org/licenses/.  */
  19
  20 #include "gmp.h"
  21 #include "gmp-impl.h"
  22
  23 int
  24 mpf_cmp (mpf_srcptr u, mpf_srcptr v) __GMP_NOTHROW
  25 {
  26   mp_srcptr up, vp;
  27   mp_size_t usize, vsize;
  28   mp_exp_t uexp, vexp;
  29   int cmp;
  30   int usign;
  31
  32   uexp = u->_mp_exp;
  33   vexp = v->_mp_exp;
  34
  35   usize = u->_mp_size;
  36   vsize = v->_mp_size;
  37
  38   /* 1. Are the signs different?  */
  39   if ((usize ^ vsize) >= 0)
  40     {
  41       /* U and V are both non-negative or both negative.  */
  42       if (usize == 0)
  43         /* vsize >= 0 */
  44         return -(vsize != 0);
  45       if (vsize == 0)
  46         /* usize >= 0 */
  47         return usize != 0;
  48       /* Fall out.  */
  49     }
  50   else
  51     {
  52       /* Either U or V is negative, but not both.  */
  53       return usize >= 0 ? 1 : -1;
  54     }
  55
  56   /* U and V have the same sign and are both non-zero.  */
  57
  58   usign = usize >= 0 ? 1 : -1;
  59
  60   /* 2. Are the exponents different?  */
  61   if (uexp > vexp)
  62     return usign;
  63   if (uexp < vexp)
  64     return -usign;
  65
  66   usize = ABS (usize);
  67   vsize = ABS (vsize);
  68
  69   up = u->_mp_d;
  70   vp = v->_mp_d;
  71
  72 #define STRICT_MPF_NORMALIZATION 0
  73 #if ! STRICT_MPF_NORMALIZATION
  74   /* Ignore zeroes at the low end of U and V.  */
  75   while (up[0] == 0)
  76     {
  77       up++;
  78       usize--;
  79     }
  80   while (vp[0] == 0)
  81     {
  82       vp++;
  83       vsize--;
  84     }
  85 #endif
  86
  87   if (usize > vsize)
  88     {
  89       cmp = mpn_cmp (up + usize - vsize, vp, vsize);
  90       if (cmp == 0)
  91         return usign;
  92     }
  93   else if (vsize > usize)
  94     {
  95       cmp = mpn_cmp (up, vp + vsize - usize, usize);
  96       if (cmp == 0)
  97         return -usign;
  98     }
  99   else
 100     {
 101       cmp = mpn_cmp (up, vp, usize);
 102       if (cmp == 0)
 103         return 0;
 104     }
 105   return cmp > 0 ? usign : -usign;
 106 }