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/*
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 2 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, write to the Free Software Foundation, Inc.,
51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
*/
/**
* @find_last_bit
* optimized implementation of find last bit in
*/
#ifndef BITS_PER_LONG
#define BITS_PER_LONG 64
#endif
static inline int fls(int x)
{
int r = 32;
if (!x)
return 0;
if (!(x & 0xffff0000u)) {
x <<= 16;
r -= 16;
}
if (!(x & 0xff000000u)) {
x <<= 8;
r -= 8;
}
if (!(x & 0xf0000000u)) {
x <<= 4;
r -= 4;
}
if (!(x & 0xc0000000u)) {
x <<= 2;
r -= 2;
}
if (!(x & 0x80000000u)) {
x <<= 1;
r -= 1;
}
return r;
}
unsigned long gf_tw_find_last_bit(const unsigned long *addr, unsigned long size)
{
unsigned long words;
unsigned long tmp;
/* Start at final word. */
words = size / BITS_PER_LONG;
/* Partial final word? */
if (size & (BITS_PER_LONG-1)) {
tmp = (addr[words] & (~0UL >> (BITS_PER_LONG
- (size & (BITS_PER_LONG-1)))));
if (tmp)
goto found;
}
while (words) {
tmp = addr[--words];
if (tmp) {
found:
return words * BITS_PER_LONG + fls(tmp);
}
}
/* Not found */
return size;
}
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