1 /* ffsl.h -- find the first set bit in a word.
2 Copyright (C) 2011 Free Software Foundation, Inc.
4 This program is free software: you can redistribute it and/or modify
5 it under the terms of the GNU General Public License as published by
6 the Free Software Foundation; either version 3 of the License, or
7 (at your option) any later version.
9 This program is distributed in the hope that it will be useful,
10 but WITHOUT ANY WARRANTY; without even the implied warranty of
11 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
12 GNU General Public License for more details.
14 You should have received a copy of the GNU General Public License
15 along with this program. If not, see <http://www.gnu.org/licenses/>. */
17 /* Written by Eric Blake. */
19 /* This file is meant to be included by ffsl.c and ffsll.c, after
20 they have defined FUNC and TYPE. */
27 #if !defined FUNC || !defined TYPE
34 #if (__GNUC__ > 3 || (__GNUC__ == 3 && __GNUC_MINOR__ >= 4)) && defined GCC_BUILTIN
35 return GCC_BUILTIN (i);
37 if (sizeof (TYPE) == sizeof (int))
42 /* Split j into chunks, and look at one chunk after the other. */
43 /* Define chunk_bits so as to avoid a GCC warning
44 "right shift count >= width of type"
45 if sizeof (TYPE) == sizeof (int). */
48 chunk_bits = (sizeof (TYPE) != sizeof (int)
49 ? CHAR_BIT * sizeof (unsigned int)
54 /* It is tempting to write if (!j) here, but if we do this,
55 Solaris 10/x86 "cc -O" miscompiles the code. */
61 return result + ffs ((unsigned int) j);