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/*
* Copyright (c) 2006 Ondrej Palkovsky
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
*
* - Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* - Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
* - The name of the author may not be used to endorse or promote products
* derived from this software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
* IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
* OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
* IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
* NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
* THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
/** @addtogroup generic
* @{
*/
/** @file
*/
#ifndef LIBC_BITOPS_H_
#define LIBC_BITOPS_H_
#include <sys/types.h>
/** Return position of first non-zero bit from left (i.e. [log_2(arg)]).
*
* If number is zero, it returns 0
*/
static inline unsigned int fnzb32(uint32_t arg)
{
unsigned int n = 0;
if (arg >> 16) {
arg >>= 16;
n += 16;
}
if (arg >> 8) {
arg >>= 8;
n += 8;
}
if (arg >> 4) {
arg >>= 4;
n += 4;
}
if (arg >> 2) {
arg >>= 2;
n += 2;
}
if (arg >> 1) {
arg >>= 1;
n += 1;
}
return n;
}
static inline unsigned int fnzb64(uint64_t arg)
{
unsigned int n = 0;
if (arg >> 32) {
arg >>= 32;
n += 32;
}
return (n + fnzb32((uint32_t) arg));
}
static inline unsigned int fnzb(size_t arg)
{
return fnzb64(arg);
}
#endif
/** @}
*/
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