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/* $NetBSD: bitstring.h,v 1.8 2005/02/06 04:38:18 perry Exp $ */

/*
* Copyright (c) 1989, 1993
* The Regents of the University of California. All rights reserved.
*
* This code is derived from software contributed to Berkeley by
* Paul Vixie.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. 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.
* 3. Neither the name of the University nor the names of its contributors
* may be used to endorse or promote products derived from this software
* without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``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 REGENTS OR CONTRIBUTORS 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.
*
* @(#)bitstring.h 8.1 (Berkeley) 7/19/93
*/

#ifndef _BITSTRING_H_
#define _BITSTRING_H_

/* modified for SV/AT and bitstring bugfix by M.R.Murphy, 11oct91
* bitstr_size changed gratuitously, but shorter
* bit_alloc spelling error fixed
* the following were efficient, but didn't work, they've been made to
* work, but are no longer as efficient :-)
* bit_nclear, bit_nset, bit_ffc, bit_ffs
*/
/*
* The comment above may or may not bear any resemblance to reality.
* This code has been maintained in a confusing way, with little
* information available on the provenance of much of it. "At least it
* works."
* /s/ Perry E. Metzger, 2 Feb 98
*/
typedef unsigned char bitstr_t;

/* internal macros */
/* byte of the bitstring bit is in */
#define _bit_byte(bit) \
((bit) >> 3)

/* mask for the bit within its byte */
#define _bit_mask(bit) \
(1 << ((bit)&0x7))

/* external macros */
/* bytes in a bitstring of nbits bits */
#define bitstr_size(nbits) \
(((nbits) + 7) >> 3)

/* allocate a bitstring */
#define bit_alloc(nbits) \
(bitstr_t *)calloc((size_t)bitstr_size(nbits), sizeof(bitstr_t))

/* allocate a bitstring on the stack */
#define bit_decl(name, nbits) \
((name)[bitstr_size(nbits)])

/* is bit N of bitstring name set? */
#define bit_test(name, bit) \
((name)[_bit_byte(bit)] & _bit_mask(bit))

/* set bit N of bitstring name */
#define bit_set(name, bit) \
((name)[_bit_byte(bit)] |= _bit_mask(bit))

/* clear bit N of bitstring name */
#define bit_clear(name, bit) \
((name)[_bit_byte(bit)] &= ~_bit_mask(bit))

/* clear bits start ... stop in bitstring */
#define bit_nclear(name, start, stop) do { \
bitstr_t *_name = name; \
int _start = start, _stop = stop; \
while (_start <= _stop) { \
bit_clear(_name, _start); \
_start++; \
} \
} while(0)

/* set bits start ... stop in bitstring */
#define bit_nset(name, start, stop) do { \
bitstr_t *_name = name; \
int _start = start, _stop = stop; \
while (_start <= _stop) { \
bit_set(_name, _start); \
_start++; \
} \
} while(0)

/* find first bit clear in name */
#define bit_ffc(name, nbits, value) do { \
bitstr_t *_name = name; \
int _bit, _nbits = nbits, _value = -1; \
for (_bit = 0; _bit < _nbits; ++_bit) \
if (!bit_test(_name, _bit)) { \
_value = _bit; \
break; \
} \
*(value) = _value; \
} while(0)

/* find first bit set in name */
#define bit_ffs(name, nbits, value) do { \
bitstr_t *_name = name; \
int _bit, _nbits = nbits, _value = -1; \
for (_bit = 0; _bit < _nbits; ++_bit) \
if (bit_test(_name, _bit)) { \
_value = _bit; \
break; \
} \
*(value) = _value; \
} while(0)

#endif /* !_BITSTRING_H_ */
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