xref: /dragonfly/contrib/gmp/mpz/cmp_si.c (revision c69bf40f)
1 /* mpz_cmp_si(u,v) -- Compare an integer U with a single-word int V.
2    Return positive, zero, or negative based on if U > V, U == V, or U < V.
3 
4 Copyright 1991, 1993, 1994, 1995, 1996, 2000, 2001, 2002 Free Software
5 Foundation, 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_si (mpz_srcptr u, signed long int v_digit) __GMP_NOTHROW
27 {
28   mp_size_t usize = u->_mp_size;
29   mp_size_t vsize;
30   mp_limb_t u_digit;
31   unsigned long int absv_digit = (unsigned long int) v_digit;
32 
33 #if GMP_NAIL_BITS != 0
34   /* FIXME.  This isn't very pretty.  */
35   mpz_t tmp;
36   mp_limb_t tt[2];
37   PTR(tmp) = tt;
38   ALLOC(tmp) = 2;
39   mpz_set_si (tmp, v_digit);
40   return mpz_cmp (u, tmp);
41 #endif
42 
43   vsize = 0;
44   if (v_digit > 0)
45     vsize = 1;
46   else if (v_digit < 0)
47     {
48       vsize = -1;
49       absv_digit = -absv_digit;
50     }
51 
52   if (usize != vsize)
53     return usize - vsize;
54 
55   if (usize == 0)
56     return 0;
57 
58   u_digit = u->_mp_d[0];
59 
60   if (u_digit == (mp_limb_t) absv_digit)
61     return 0;
62 
63   if (u_digit > (mp_limb_t) absv_digit)
64     return usize;
65   else
66     return -usize;
67 }
68