minix/include/bitstring.h

/*	$NetBSD: bitstring.h,v 1.9 2010/05/06 18:54:22 christos 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) \
	(uint32_t)((bit) >> 3)

				/* mask for the bit within its byte */
#define	_bit_mask(bit) \
	(uint32_t)((1 << (uint32_t)((bit)&0x7)))

/* external macros */
				/* bytes in a bitstring of nbits bits */
#define	bitstr_size(nbits) \
	(size_t)((uint32_t)((nbits) + 7) >> 3)

				/* allocate a bitstring */
#define	bit_alloc(nbits) \
	calloc(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) \
	/*LINTED bitwise on signed*/((name)[_bit_byte(bit)] & _bit_mask(bit))

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

				/* clear bit N of bitstring name */
#define	bit_clear(name, bit) \
	/*LINTED bitwise on signed*/((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(/*CONSTCOND*/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(/*CONSTCOND*/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(/*CONSTCOND*/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(/*CONSTCOND*/0)

#endif /* !_BITSTRING_H_ */