1 /* mpz_divisible_ui_p -- mpz by ulong divisibility test.
3 Copyright 2000, 2001, 2002 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 3 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. If not, see http://www.gnu.org/licenses/. */
26 mpz_divisible_ui_p (mpz_srcptr a, unsigned long d)
33 if (UNLIKELY (d == 0))
36 if (asize == 0) /* 0 divisible by any d */
39 /* For nails don't try to be clever if d is bigger than a limb, just fake
40 up an mpz_t and go to the main mpz_divisible_p. */
48 return mpz_divisible_p (a, dz);
52 asize = ABS(asize); /* ignore sign of a */
54 if (BELOW_THRESHOLD (asize, MODEXACT_1_ODD_THRESHOLD))
55 return mpn_mod_1 (ap, asize, (mp_limb_t) d) == 0;
59 /* Strip low zero bits to get odd d required by modexact. If d==e*2^n
60 and a is divisible by 2^n and by e, then it's divisible by d. */
62 if ((ap[0] & LOW_ZEROS_MASK (d)) != 0)
65 count_trailing_zeros (twos, (mp_limb_t) d);
69 return mpn_modexact_1_odd (ap, asize, (mp_limb_t) d) == 0;