contrib/gmp/mpz/cmp_ui.c

   1 /* mpz_cmp_ui.c -- Compare a mpz_t a with an mp_limb_t b.  Return positive,
   2   zero, or negative based on if a > b, a == b, or a < b.
   3
   4 Copyright 1991, 1993, 1994, 1995, 1996, 2001, 2002 Free Software Foundation,
   5 Inc.
   6
   7 This file is part of the GNU MP Library.
   8
   9 The GNU MP Library is free software; you can redistribute it and/or modify
  10 it under the terms of the GNU Lesser General Public License as published by
  11 the Free Software Foundation; either version 3 of the License, or (at your
  12 option) any later version.
  13
  14 The GNU MP Library is distributed in the hope that it will be useful, but
  15 WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
  16 or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU Lesser General Public
  17 License for more details.
  18
  19 You should have received a copy of the GNU Lesser General Public License
  20 along with the GNU MP Library.  If not, see http://www.gnu.org/licenses/.  */
  21
  22 #include "gmp.h"
  23 #include "gmp-impl.h"
  24
  25 int
  26 _mpz_cmp_ui (mpz_srcptr u, unsigned long int v_digit) __GMP_NOTHROW
  27 {
  28   mp_ptr up;
  29   mp_size_t un;
  30   mp_limb_t ul;
  31
  32   up = PTR(u);
  33   un = SIZ(u);
  34
  35   if (un == 0)
  36     return -(v_digit != 0);
  37
  38   if (un == 1)
  39     {
  40       ul = up[0];
  41       if (ul > v_digit)
  42         return 1;
  43       if (ul < v_digit)
  44         return -1;
  45       return 0;
  46     }
  47
  48 #if GMP_NAIL_BITS != 0
  49   if (v_digit > GMP_NUMB_MAX)
  50     {
  51       if (un == 2)
  52         {
  53           ul = up[0] + (up[1] << GMP_NUMB_BITS);
  54
  55           if ((up[1] >> GMP_NAIL_BITS) != 0)
  56             return 1;
  57
  58           if (ul > v_digit)
  59             return 1;
  60           if (ul < v_digit)
  61             return -1;
  62           return 0;
  63         }
  64     }
  65 #endif
  66
  67   return un > 0 ? 1 : -1;
  68 }