Annotation of OpenXM_contrib/gmp/mpz/mul_2exp.c, Revision 1.1.1.3
1.1 maekawa 1: /* mpz_mul_2exp -- Multiply a bignum by 2**CNT
2:
1.1.1.3 ! ohara 3: Copyright 1991, 1993, 1994, 1996, 2001, 2002 Free Software Foundation, Inc.
1.1 maekawa 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
1.1.1.2 maekawa 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
1.1 maekawa 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
1.1.1.2 maekawa 14: or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public
1.1 maekawa 15: License for more details.
16:
1.1.1.2 maekawa 17: You should have received a copy of the GNU Lesser General Public License
1.1 maekawa 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_mul_2exp (mpz_ptr w, mpz_srcptr u, unsigned long int cnt)
27: {
28: mp_size_t usize = u->_mp_size;
29: mp_size_t abs_usize = ABS (usize);
30: mp_size_t wsize;
31: mp_size_t limb_cnt;
32: mp_ptr wp;
33: mp_limb_t wlimb;
34:
35: if (usize == 0)
36: {
37: w->_mp_size = 0;
38: return;
39: }
40:
1.1.1.3 ! ohara 41: limb_cnt = cnt / GMP_NUMB_BITS;
1.1 maekawa 42: wsize = abs_usize + limb_cnt + 1;
43: if (w->_mp_alloc < wsize)
44: _mpz_realloc (w, wsize);
45:
46: wp = w->_mp_d;
47: wsize = abs_usize + limb_cnt;
48:
1.1.1.3 ! ohara 49: cnt %= GMP_NUMB_BITS;
1.1 maekawa 50: if (cnt != 0)
51: {
52: wlimb = mpn_lshift (wp + limb_cnt, u->_mp_d, abs_usize, cnt);
53: if (wlimb != 0)
54: {
55: wp[wsize] = wlimb;
56: wsize++;
57: }
58: }
59: else
60: {
61: MPN_COPY_DECR (wp + limb_cnt, u->_mp_d, abs_usize);
62: }
63:
64: /* Zero all whole limbs at low end. Do it here and not before calling
65: mpn_lshift, not to lose for U == W. */
66: MPN_ZERO (wp, limb_cnt);
67:
68: w->_mp_size = usize >= 0 ? wsize : -wsize;
69: }
FreeBSD-CVSweb <freebsd-cvsweb@FreeBSD.org>