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/*
* Copyright (C) 2013 Freie Universität Berlin
*
* This file is subject to the terms and conditions of the GNU Lesser
* General Public License v2.1. See the file LICENSE in the top level
* directory for more details.
*/
/**
* @ingroup core_util
* @{
*
* @file bitarithm.c
* @brief Bit arithmetic helper functions implementation
*
* @author Kaspar Schleiser <kaspar@schleiser.de>
* @author Martin Lenders <mlenders@inf.fu-berlin.de>
* @author René Kijewski <rene.kijewski@fu-berlin.de>
*
* @}
*/
#include <stdio.h>
#include "bitarithm.h"
unsigned bitarithm_msb(unsigned v)
{
if ((signed) v >= 0) {
v &= -v;
return bitarithm_lsb(v);
}
else {
return sizeof (v) * 8 - 1;
}
}
unsigned bitarithm_lsb(unsigned v)
{
unsigned r = 0;
while ((v & 1) == 0) {
v >>= 1;
r++;
}
return r;
}
unsigned bitarithm_bits_set(unsigned v)
{
unsigned c; // c accumulates the total bits set in v
for (c = 0; v; c++) {
v &= v - 1; // clear the least significant bit set
}
return c;
}