Annotation of OpenXM_contrib/gmp/mpz/ui_sub.c, Revision 1.1.1.1
1.1 ohara 1: /* mpz_ui_sub -- Subtract an unsigned one-word integer and an mpz_t.
2:
3: Copyright 2002 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 2.1 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; see the file COPYING.LIB. If not, write to
19: the Free Software Foundation, Inc., 59 Temple Place - Suite 330, Boston,
20: MA 02111-1307, USA. */
21:
22: #include "gmp.h"
23: #include "gmp-impl.h"
24:
25: void
26: mpz_ui_sub (mpz_ptr w, unsigned long int uval, mpz_srcptr v)
27: {
28: mp_ptr vp, wp;
29: mp_size_t vn, wn;
30: mp_limb_t cy;
31:
32: #if GMP_NAIL_BITS != 0
33: if (uval > GMP_NUMB_MAX)
34: {
35: mpz_t u;
36: mp_limb_t ul[2];
37: PTR(u) = ul;
38: ul[0] = uval & GMP_NUMB_MASK;
39: ul[1] = uval >> GMP_NUMB_BITS;
40: SIZ(u) = 2;
41: mpz_sub (w, u, v);
42: return;
43: }
44: #endif
45:
46: vp = PTR(v);
47: vn = SIZ(v);
48:
49: wp = PTR(w);
50:
51: if (vn > 1)
52: {
53: wp = MPZ_REALLOC (w, vn);
54: vp = PTR(v);
55: mpn_sub_1 (wp, vp, vn, (mp_limb_t) uval);
56: wn = -(vn - (wp[vn - 1] == 0));
57: }
58: else if (vn == 1)
59: {
60: if (uval >= vp[0])
61: {
62: wp[0] = uval - vp[0];
63: wn = wp[0] != 0;
64: }
65: else
66: {
67: wp[0] = vp[0] - uval;
68: wn = -1;
69: }
70: }
71: else if (vn == 0)
72: {
73: wp[0] = uval;
74: wn = uval != 0;
75: }
76: else /* (vn < 0) */
77: {
78: vn = -vn;
79: wp = MPZ_REALLOC (w, vn + 1);
80: vp = PTR(v);
81: cy = mpn_add_1 (wp, vp, vn, (mp_limb_t) uval);
82: wp[vn] = cy;
83: wn = vn + (cy != 0);
84: }
85:
86: SIZ(w) = wn;
87: }
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