0,0 → 1,94 |
/* |
* 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 <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 int fnzb32(uint32_t arg) |
{ |
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 int fnzb64(uint64_t arg) |
{ |
int n = 0; |
|
if (arg >> 32) { |
arg >>= 32; |
n += 32; |
} |
|
return n + fnzb32((uint32_t) arg); |
} |
|
#define fnzb(x) fnzb32(x) |
|
#endif |
|
/** @} |
*/ |