source/libs/gmp/gmp-src/mpf/cmp.c

   1 /* mpf_cmp -- Compare two floats.
   2
   3 Copyright 1993, 1994, 1996, 2001, 2015 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 either:
   9
  10   * the GNU Lesser General Public License as published by the Free
  11     Software Foundation; either version 3 of the License, or (at your
  12     option) any later version.
  13
  14 or
  15
  16   * the GNU General Public License as published by the Free Software
  17     Foundation; either version 2 of the License, or (at your option) any
  18     later version.
  19
  20 or both in parallel, as here.
  21
  22 The GNU MP Library is distributed in the hope that it will be useful, but
  23 WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
  24 or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  25 for more details.
  26
  27 You should have received copies of the GNU General Public License and the
  28 GNU Lesser General Public License along with the GNU MP Library.  If not,
  29 see https://www.gnu.org/licenses/.  */
  30
  31 #include "gmp.h"
  32 #include "gmp-impl.h"
  33
  34 int
  35 mpf_cmp (mpf_srcptr u, mpf_srcptr v) __GMP_NOTHROW
  36 {
  37   mp_srcptr up, vp;
  38   mp_size_t usize, vsize;
  39   mp_exp_t uexp, vexp;
  40   int cmp;
  41   int usign;
  42
  43   usize = SIZ(u);
  44   vsize = SIZ(v);
  45   usign = usize >= 0 ? 1 : -1;
  46
  47   /* 1. Are the signs different?  */
  48   if ((usize ^ vsize) >= 0)
  49     {
  50       /* U and V are both non-negative or both negative.  */
  51       if (usize == 0)
  52         /* vsize >= 0 */
  53         return -(vsize != 0);
  54       if (vsize == 0)
  55         /* usize >= 0 */
  56         return usize != 0;
  57       /* Fall out.  */
  58     }
  59   else
  60     {
  61       /* Either U or V is negative, but not both.  */
  62       return usign;
  63     }
  64
  65   /* U and V have the same sign and are both non-zero.  */
  66
  67   uexp = EXP(u);
  68   vexp = EXP(v);
  69
  70   /* 2. Are the exponents different?  */
  71   if (uexp > vexp)
  72     return usign;
  73   if (uexp < vexp)
  74     return -usign;
  75
  76   usize = ABS (usize);
  77   vsize = ABS (vsize);
  78
  79   up = PTR (u);
  80   vp = PTR (v);
  81
  82 #define STRICT_MPF_NORMALIZATION 0
  83 #if ! STRICT_MPF_NORMALIZATION
  84   /* Ignore zeroes at the low end of U and V.  */
  85   do {
  86     mp_limb_t tl;
  87     tl = up[0];
  88     MPN_STRIP_LOW_ZEROS_NOT_ZERO (up, usize, tl);
  89     tl = vp[0];
  90     MPN_STRIP_LOW_ZEROS_NOT_ZERO (vp, vsize, tl);
  91   } while (0);
  92 #endif
  93
  94   if (usize > vsize)
  95     {
  96       cmp = mpn_cmp (up + usize - vsize, vp, vsize);
  97       /* if (cmp == 0) */
  98       /*        return usign; */
  99       ++cmp;
 100     }
 101   else if (vsize > usize)
 102     {
 103       cmp = mpn_cmp (up, vp + vsize - usize, usize);
 104       /* if (cmp == 0) */
 105       /*        return -usign; */
 106     }
 107   else
 108     {
 109       cmp = mpn_cmp (up, vp, usize);
 110       if (cmp == 0)
 111         return 0;
 112     }
 113   return cmp > 0 ? usign : -usign;
 114 }