3 Copyright (C) 1994, 1996, 2000 Free Software Foundation, Inc.
5 This file is part of the GNU MP Library.
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.
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.
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. */
26 /* Does not work for U == 0 or V == 0. It would be tough to make it work for
27 V == 0 since gcd(x,0) = x, and U does not generally fit in an mp_limb_t. */
31 mpn_gcd_1 (mp_srcptr up, mp_size_t size, mp_limb_t vlimb)
33 mpn_gcd_1 (up, size, vlimb)
40 unsigned long int u_low_zero_bits, v_low_zero_bits;
44 ulimb = mpn_mod_1 (up, size, vlimb);
51 /* Need to eliminate low zero bits. */
52 count_trailing_zeros (u_low_zero_bits, ulimb);
53 ulimb >>= u_low_zero_bits;
55 count_trailing_zeros (v_low_zero_bits, vlimb);
56 vlimb >>= v_low_zero_bits;
58 while (ulimb != vlimb)
65 while ((ulimb & 1) == 0);
67 else /* vlimb > ulimb. */
72 while ((vlimb & 1) == 0);
76 return ulimb << MIN (u_low_zero_bits, v_low_zero_bits);