/*-
 * 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.
 * 4. 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.
 *
 * Copyright (c) 2014 Spectra Logic Corporation
 * All rights reserved.
 *
 * 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,
 *    without modification.
 * 2. Redistributions in binary form must reproduce at minimum a disclaimer
 *    substantially similar to the "NO WARRANTY" disclaimer below
 *    ("Disclaimer") and any redistribution must be conditioned upon
 *    including a substantially similar Disclaimer requirement for further
 *    binary redistribution.
 *
 * NO WARRANTY
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTIBILITY AND FITNESS FOR
 * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
 * HOLDERS OR CONTRIBUTORS BE LIABLE FOR 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 DAMAGES.
 *
 * $FreeBSD: stable/9/sys/sys/bitstring.h 139825 2005-01-07 02:29:27Z imp $
 */

#ifndef _SYS_BITSTRING_H_
#define	_SYS_BITSTRING_H_

typedef	unsigned long bitstr_t;

/*---------------------- Private Implementation Details ----------------------*/
#define	_BITSTR_MASK (~0UL)
#define	_BITSTR_BITS (sizeof(bitstr_t) * 8)

/* bitstr_t in bit string containing the bit. */
static inline int
_bit_idx(int _bit)
{
	return (_bit / _BITSTR_BITS);
}

/* bit number within bitstr_t at _bit_idx(_bit). */
static inline int
_bit_offset(int _bit)
{
	return (_bit % _BITSTR_BITS);
}

/* Mask for the bit within its long. */
static inline bitstr_t
_bit_mask(int _bit)
{
	return (1UL << _bit_offset(_bit));
}

static inline bitstr_t
_bit_make_mask(int _start, int _stop)
{
	return ((_BITSTR_MASK << _bit_offset(_start)) &
	    (_BITSTR_MASK >> (_BITSTR_BITS - _bit_offset(_stop) - 1)));
}

/*----------------------------- Public Interface -----------------------------*/
/* Number of bytes consumed by a bit string of nbits bits */
#define	bitstr_size(_nbits) \
	(((_nbits) + _BITSTR_BITS - 1) / 8)

/* Allocate a bit string initialized with no bits set. */
#ifdef _KERNEL
static inline bitstr_t *
bit_alloc(int _nbits, struct malloc_type *type, int flags)
{
	return ((bitstr_t *)malloc(bitstr_size(_nbits), type, flags | M_ZERO));
}
#else
static inline bitstr_t *
bit_alloc(int _nbits)
{
	return ((bitstr_t *)calloc(bitstr_size(_nbits), 1));
}
#endif

/* Free a bit string. */
#ifdef _KERNEL
static inline void
bit_free(bitstr_t *_bitstr, struct malloc_type *type)
{
	free(_bitstr, type);
}
#else
static inline void
bit_free(bitstr_t *_bitstr)
{
	free(_bitstr);
}
#endif

/* Allocate a bit string on the stack with no bits set. */
#define	bit_decl(name, nbits) \
	((name)[bitstr_size(nbits) / sizeof(bitstr_t)])

/* Is bit N of bit string set? */
static inline int
bit_test(const bitstr_t *_bitstr, int _bit)
{
	return ((_bitstr[_bit_idx(_bit)] & _bit_mask(_bit)) != 0);
}

/* Set bit N of bit string. */
static inline void
bit_set(bitstr_t *_bitstr, int _bit)
{
	_bitstr[_bit_idx(_bit)] |= _bit_mask(_bit);
}

/* clear bit N of bit string name */
static inline void
bit_clear(bitstr_t *_bitstr, int _bit)
{
	_bitstr[_bit_idx(_bit)] &= ~_bit_mask(_bit);
}

/* Set bits start ... stop inclusive in bit string. */
static inline void
bit_nset(bitstr_t *_bitstr, int _start, int _stop)
{
	bitstr_t *_stopbitstr;

	_stopbitstr = _bitstr + _bit_idx(_stop);
	_bitstr += _bit_idx(_start);

	if (_bitstr == _stopbitstr) {
		*_bitstr |= _bit_make_mask(_start, _stop);
	} else {
		*_bitstr |= _bit_make_mask(_start, _BITSTR_BITS - 1);
		while (++_bitstr < _stopbitstr)
	    		*_bitstr = _BITSTR_MASK;
		*_stopbitstr |= _bit_make_mask(0, _stop);
	}
}

/* Clear bits start ... stop inclusive in bit string. */
static inline void
bit_nclear(bitstr_t *_bitstr, int _start, int _stop)
{
	bitstr_t *_stopbitstr;

	_stopbitstr = _bitstr + _bit_idx(_stop);
	_bitstr += _bit_idx(_start);

	if (_bitstr == _stopbitstr) {
		*_bitstr &= ~_bit_make_mask(_start, _stop);
	} else {
		*_bitstr &= ~_bit_make_mask(_start, _BITSTR_BITS - 1);
		while (++_bitstr < _stopbitstr)
			*_bitstr = 0;
		*_stopbitstr &= ~_bit_make_mask(0, _stop);
	}
}

/* Find the first bit set in bit string at or after bit start. */
static inline void
bit_ffs_at(bitstr_t *_bitstr, int _start, int _nbits, int *_result)
{
	bitstr_t *_curbitstr;
	bitstr_t *_stopbitstr;
	bitstr_t _test;
	int _value, _offset;

	if (_nbits > 0) {
		_curbitstr = _bitstr + _bit_idx(_start);
		_stopbitstr = _bitstr + _bit_idx(_nbits - 1);

		_test = *_curbitstr;
		if (_bit_offset(_start) != 0)
			_test &= _bit_make_mask(_start, _BITSTR_BITS - 1);
		while (_test == 0 && _curbitstr < _stopbitstr)
			_test = *(++_curbitstr);
		
		_offset = ffsl(_test);
		_value = ((_curbitstr - _bitstr) * _BITSTR_BITS) + _offset - 1;
		if (_offset == 0 || _value >= _nbits)
			_value = -1;
	} else {
		_value = -1;
	}
	*_result = _value;
}

/* Find the first bit clear in bit string at or after bit start. */
static inline void
bit_ffc_at(bitstr_t *_bitstr, int _start, int _nbits, int *_result)
{
	bitstr_t *_curbitstr;
	bitstr_t *_stopbitstr;
	bitstr_t _test;
	int _value, _offset;

	if (_nbits > 0) {
		_curbitstr = _bitstr + _bit_idx(_start);
		_stopbitstr = _bitstr + _bit_idx(_nbits - 1);

		_test = *_curbitstr;
		if (_bit_offset(_start) != 0)
			_test |= _bit_make_mask(0, _start - 1);
		while (_test == _BITSTR_MASK && _curbitstr < _stopbitstr)
			_test = *(++_curbitstr);
		
		_offset = ffsl(~_test);
		_value = ((_curbitstr - _bitstr) * _BITSTR_BITS) + _offset - 1;
		if (_offset == 0 || _value >= _nbits)
			_value = -1;
	} else {
		_value = -1;
	}
	*_result = _value;
}

/* Find the first bit set in bit string. */
static inline void
bit_ffs(bitstr_t *_bitstr, int _nbits, int *_result)
{
	bit_ffs_at(_bitstr, /*start*/0, _nbits, _result);
}

/* Find the first bit clear in bit string. */
static inline void
bit_ffc(bitstr_t *_bitstr, int _nbits, int *_result)
{
	bit_ffc_at(_bitstr, /*start*/0, _nbits, _result);
}

#endif	/* _SYS_BITSTRING_H_ */
