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/*
* Copyright (c) 2013 Richard Braun.
*
* This program is free software: you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation, either version 3 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program. If not, see <http://www.gnu.org/licenses/>.
*/
#include <kern/bitmap.h>
#include <kern/limits.h>
static inline unsigned long
bitmap_find_next_compute_complement(unsigned long word, int nr_bits)
{
if (nr_bits < LONG_BIT)
word |= (((unsigned long)-1) << nr_bits);
return ~word;
}
int
bitmap_find_next_bit(const unsigned long *bm, int nr_bits, int bit,
int complement)
{
const unsigned long *start, *end;
unsigned long word;
start = bm;
end = bm + BITMAP_LONGS(nr_bits);
if (bit >= LONG_BIT) {
bitmap_lookup(bm, bit);
nr_bits -= ((bm - start) * LONG_BIT);
}
word = *bm;
if (complement)
word = bitmap_find_next_compute_complement(word, nr_bits);
if (bit < LONG_BIT)
word &= ~(bitmap_mask(bit) - 1);
for (;;) {
bit = __builtin_ffsl(word);
if (bit != 0)
return ((bm - start) * LONG_BIT) + bit - 1;
bm++;
if (bm >= end)
return -1;
nr_bits -= LONG_BIT;
word = *bm;
if (complement)
word = bitmap_find_next_compute_complement(word, nr_bits);
}
}
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