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771 palkovsky 1 
/*
2071 jermar 2 
 * Copyright (c) 2006 Ondrej Palkovsky
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 * All rights reserved.
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 *
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 * Redistribution and use in source and binary forms, with or without
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 * modification, are permitted provided that the following conditions
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 * are met:
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 *
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 * - Redistributions of source code must retain the above copyright
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 *   notice, this list of conditions and the following disclaimer.
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 * - Redistributions in binary form must reproduce the above copyright
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 *   notice, this list of conditions and the following disclaimer in the
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 *   documentation and/or other materials provided with the distribution.
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 * - The name of the author may not be used to endorse or promote products
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 *   derived from this software without specific prior written permission.
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 *
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 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
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 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
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 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
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 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
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 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
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 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
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 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
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 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
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 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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 */
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/** @addtogroup generic
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 * @{
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 */
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/** @file
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 */
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#ifndef LIBC_BITOPS_H_
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#define LIBC_BITOPS_H_
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#include <sys/types.h>
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/** Return position of first non-zero bit from left (i.e. [log_2(arg)]).
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 *
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 * If number is zero, it returns 0
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 */
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static inline unsigned int fnzb32(uint32_t arg)
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{
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    unsigned int n = 0;
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    if (arg >> 16) {
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        arg >>= 16;
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        n += 16;
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    }
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    if (arg >> 8) {
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        arg >>= 8;
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        n += 8;
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    }
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    if (arg >> 4) {
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        arg >>= 4;
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        n += 4;
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    }
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    if (arg >> 2) {
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        arg >>= 2;
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        n += 2;
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    }
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    if (arg >> 1) {
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        arg >>= 1;
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        n += 1;
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    }
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    return n;
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}
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static inline unsigned int fnzb64(uint64_t arg)
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{
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    unsigned int n = 0;
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    if (arg >> 32) {
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        arg >>= 32;
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        n += 32;
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    }
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    return (n + fnzb32((uint32_t) arg));
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}
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static inline unsigned int fnzb(size_t arg)
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{
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    return fnzb64(arg);
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}
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#endif
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/** @}
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 */