1 /* mpn_scan1 -- Scan from a given bit position for the next set bit.
3 Copyright 1994, 1996, 2001, 2002, 2004 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/. */
24 /* Argument constraints:
25 1. U must sooner or later have a limb != 0.
29 mpn_scan1 (register mp_srcptr up,
30 register unsigned long int starting_bit)
32 mp_size_t starting_word;
37 /* Start at the word implied by STARTING_BIT. */
38 starting_word = starting_bit / GMP_NUMB_BITS;
39 p = up + starting_word;
42 /* Mask off any bits before STARTING_BIT in the first limb. */
43 alimb &= - (mp_limb_t) 1 << (starting_bit % GMP_NUMB_BITS);
48 count_trailing_zeros (cnt, alimb);
49 return (p - up - 1) * GMP_NUMB_BITS + cnt;