The Design and Implementation of the FreeBSD Operating System, Second Edition
Now available: The Design and Implementation of the FreeBSD Operating System (Second Edition)


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FreeBSD/Linux Kernel Cross Reference
sys/sys/bitstring.h

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    1 /*-
    2  * SPDX-License-Identifier: BSD-3-Clause
    3  *
    4  * Copyright (c) 1989, 1993
    5  *      The Regents of the University of California.  All rights reserved.
    6  *
    7  * This code is derived from software contributed to Berkeley by
    8  * Paul Vixie.
    9  *
   10  * Redistribution and use in source and binary forms, with or without
   11  * modification, are permitted provided that the following conditions
   12  * are met:
   13  * 1. Redistributions of source code must retain the above copyright
   14  *    notice, this list of conditions and the following disclaimer.
   15  * 2. Redistributions in binary form must reproduce the above copyright
   16  *    notice, this list of conditions and the following disclaimer in the
   17  *    documentation and/or other materials provided with the distribution.
   18  * 3. Neither the name of the University nor the names of its contributors
   19  *    may be used to endorse or promote products derived from this software
   20  *    without specific prior written permission.
   21  *
   22  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
   23  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
   24  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
   25  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
   26  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
   27  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
   28  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
   29  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
   30  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
   31  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
   32  * SUCH DAMAGE.
   33  *
   34  * Copyright (c) 2014 Spectra Logic Corporation
   35  * All rights reserved.
   36  *
   37  * Redistribution and use in source and binary forms, with or without
   38  * modification, are permitted provided that the following conditions
   39  * are met:
   40  * 1. Redistributions of source code must retain the above copyright
   41  *    notice, this list of conditions, and the following disclaimer,
   42  *    without modification.
   43  * 2. Redistributions in binary form must reproduce at minimum a disclaimer
   44  *    substantially similar to the "NO WARRANTY" disclaimer below
   45  *    ("Disclaimer") and any redistribution must be conditioned upon
   46  *    including a substantially similar Disclaimer requirement for further
   47  *    binary redistribution.
   48  *
   49  * NO WARRANTY
   50  * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
   51  * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
   52  * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTIBILITY AND FITNESS FOR
   53  * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
   54  * HOLDERS OR CONTRIBUTORS BE LIABLE FOR SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
   55  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
   56  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
   57  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
   58  * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING
   59  * IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
   60  * POSSIBILITY OF SUCH DAMAGES.
   61  *
   62  * $FreeBSD: head/sys/sys/bitstring.h 326023 2017-11-20 19:43:44Z pfg $
   63  */
   64 #ifndef _SYS_BITSTRING_H_
   65 #define _SYS_BITSTRING_H_
   66 
   67 #ifdef _KERNEL
   68 #include <sys/libkern.h>
   69 #include <sys/malloc.h>
   70 #endif
   71 
   72 #include <sys/types.h>
   73 
   74 typedef unsigned long bitstr_t;
   75 
   76 /*---------------------- Private Implementation Details ----------------------*/
   77 #define _BITSTR_MASK (~0UL)
   78 #define _BITSTR_BITS (sizeof(bitstr_t) * 8)
   79 
   80 #ifdef roundup2
   81 #define        _bit_roundup2 roundup2
   82 #else
   83 #define        _bit_roundup2(x, y)        (((x)+((y)-1))&(~((y)-1))) /* if y is powers of two */
   84 #endif
   85 
   86 /* bitstr_t in bit string containing the bit. */
   87 static inline int
   88 _bit_idx(int _bit)
   89 {
   90         return (_bit / _BITSTR_BITS);
   91 }
   92 
   93 /* bit number within bitstr_t at _bit_idx(_bit). */
   94 static inline int
   95 _bit_offset(int _bit)
   96 {
   97         return (_bit % _BITSTR_BITS);
   98 }
   99 
  100 /* Mask for the bit within its long. */
  101 static inline bitstr_t
  102 _bit_mask(int _bit)
  103 {
  104         return (1UL << _bit_offset(_bit));
  105 }
  106 
  107 static inline bitstr_t
  108 _bit_make_mask(int _start, int _stop)
  109 {
  110         return ((_BITSTR_MASK << _bit_offset(_start)) &
  111             (_BITSTR_MASK >> (_BITSTR_BITS - _bit_offset(_stop) - 1)));
  112 }
  113 
  114 /*----------------------------- Public Interface -----------------------------*/
  115 /* Number of bytes allocated for a bit string of nbits bits */
  116 #define bitstr_size(_nbits) (_bit_roundup2(_nbits, _BITSTR_BITS) / 8)
  117 
  118 /* Allocate a bit string initialized with no bits set. */
  119 #ifdef _KERNEL
  120 static inline bitstr_t *
  121 bit_alloc(int _nbits, struct malloc_type *type, int flags)
  122 {
  123         return ((bitstr_t *)malloc(bitstr_size(_nbits), type, flags | M_ZERO));
  124 }
  125 #else
  126 static inline bitstr_t *
  127 bit_alloc(int _nbits)
  128 {
  129         return ((bitstr_t *)calloc(bitstr_size(_nbits), 1));
  130 }
  131 #endif
  132 
  133 /* Allocate a bit string on the stack */
  134 #define bit_decl(name, nbits) \
  135         ((name)[bitstr_size(nbits) / sizeof(bitstr_t)])
  136 
  137 /* Is bit N of bit string set? */
  138 static inline int
  139 bit_test(const bitstr_t *_bitstr, int _bit)
  140 {
  141         return ((_bitstr[_bit_idx(_bit)] & _bit_mask(_bit)) != 0);
  142 }
  143 
  144 /* Set bit N of bit string. */
  145 static inline void
  146 bit_set(bitstr_t *_bitstr, int _bit)
  147 {
  148         _bitstr[_bit_idx(_bit)] |= _bit_mask(_bit);
  149 }
  150 
  151 /* clear bit N of bit string name */
  152 static inline void
  153 bit_clear(bitstr_t *_bitstr, int _bit)
  154 {
  155         _bitstr[_bit_idx(_bit)] &= ~_bit_mask(_bit);
  156 }
  157 
  158 /* Set bits start ... stop inclusive in bit string. */
  159 static inline void
  160 bit_nset(bitstr_t *_bitstr, int _start, int _stop)
  161 {
  162         bitstr_t *_stopbitstr;
  163 
  164         _stopbitstr = _bitstr + _bit_idx(_stop);
  165         _bitstr += _bit_idx(_start);
  166 
  167         if (_bitstr == _stopbitstr) {
  168                 *_bitstr |= _bit_make_mask(_start, _stop);
  169         } else {
  170                 *_bitstr |= _bit_make_mask(_start, _BITSTR_BITS - 1);
  171                 while (++_bitstr < _stopbitstr)
  172                         *_bitstr = _BITSTR_MASK;
  173                 *_stopbitstr |= _bit_make_mask(0, _stop);
  174         }
  175 }
  176 
  177 /* Clear bits start ... stop inclusive in bit string. */
  178 static inline void
  179 bit_nclear(bitstr_t *_bitstr, int _start, int _stop)
  180 {
  181         bitstr_t *_stopbitstr;
  182 
  183         _stopbitstr = _bitstr + _bit_idx(_stop);
  184         _bitstr += _bit_idx(_start);
  185 
  186         if (_bitstr == _stopbitstr) {
  187                 *_bitstr &= ~_bit_make_mask(_start, _stop);
  188         } else {
  189                 *_bitstr &= ~_bit_make_mask(_start, _BITSTR_BITS - 1);
  190                 while (++_bitstr < _stopbitstr)
  191                         *_bitstr = 0;
  192                 *_stopbitstr &= ~_bit_make_mask(0, _stop);
  193         }
  194 }
  195 
  196 /* Find the first bit set in bit string at or after bit start. */
  197 static inline void
  198 bit_ffs_at(bitstr_t *_bitstr, int _start, int _nbits, int *_result)
  199 {
  200         bitstr_t *_curbitstr;
  201         bitstr_t *_stopbitstr;
  202         bitstr_t _test;
  203         int _value, _offset;
  204 
  205         if (_nbits > 0) {
  206                 _curbitstr = _bitstr + _bit_idx(_start);
  207                 _stopbitstr = _bitstr + _bit_idx(_nbits - 1);
  208 
  209                 _test = *_curbitstr;
  210                 if (_bit_offset(_start) != 0)
  211                         _test &= _bit_make_mask(_start, _BITSTR_BITS - 1);
  212                 while (_test == 0 && _curbitstr < _stopbitstr)
  213                         _test = *(++_curbitstr);
  214 
  215                 _offset = ffsl(_test);
  216                 _value = ((_curbitstr - _bitstr) * _BITSTR_BITS) + _offset - 1;
  217                 if (_offset == 0 || _value >= _nbits)
  218                         _value = -1;
  219         } else {
  220                 _value = -1;
  221         }
  222         *_result = _value;
  223 }
  224 
  225 /* Find the first bit clear in bit string at or after bit start. */
  226 static inline void
  227 bit_ffc_at(bitstr_t *_bitstr, int _start, int _nbits, int *_result)
  228 {
  229         bitstr_t *_curbitstr;
  230         bitstr_t *_stopbitstr;
  231         bitstr_t _test;
  232         int _value, _offset;
  233 
  234         if (_nbits > 0) {
  235                 _curbitstr = _bitstr + _bit_idx(_start);
  236                 _stopbitstr = _bitstr + _bit_idx(_nbits - 1);
  237 
  238                 _test = *_curbitstr;
  239                 if (_bit_offset(_start) != 0)
  240                         _test |= _bit_make_mask(0, _start - 1);
  241                 while (_test == _BITSTR_MASK && _curbitstr < _stopbitstr)
  242                         _test = *(++_curbitstr);
  243 
  244                 _offset = ffsl(~_test);
  245                 _value = ((_curbitstr - _bitstr) * _BITSTR_BITS) + _offset - 1;
  246                 if (_offset == 0 || _value >= _nbits)
  247                         _value = -1;
  248         } else {
  249                 _value = -1;
  250         }
  251         *_result = _value;
  252 }
  253 
  254 /* Find the first bit set in bit string. */
  255 static inline void
  256 bit_ffs(bitstr_t *_bitstr, int _nbits, int *_result)
  257 {
  258         bit_ffs_at(_bitstr, /*start*/0, _nbits, _result);
  259 }
  260 
  261 /* Find the first bit clear in bit string. */
  262 static inline void
  263 bit_ffc(bitstr_t *_bitstr, int _nbits, int *_result)
  264 {
  265         bit_ffc_at(_bitstr, /*start*/0, _nbits, _result);
  266 }
  267 
  268 /* Count the number of bits set in a bitstr of size _nbits at or after _start */
  269 static inline void
  270 bit_count(bitstr_t *_bitstr, int _start, int _nbits, int *_result)
  271 {
  272         bitstr_t *_curbitstr, mask;
  273         int _value = 0, curbitstr_len;
  274 
  275         if (_start >= _nbits)
  276                 goto out;
  277 
  278         _curbitstr = _bitstr + _bit_idx(_start);
  279         _nbits -= _BITSTR_BITS * _bit_idx(_start);
  280         _start -= _BITSTR_BITS * _bit_idx(_start);
  281 
  282         if (_start > 0) {
  283                 curbitstr_len = (int)_BITSTR_BITS < _nbits ?
  284                                 (int)_BITSTR_BITS : _nbits;
  285                 mask = _bit_make_mask(_start, _bit_offset(curbitstr_len - 1));
  286                 _value += __bitcountl(*_curbitstr & mask);
  287                 _curbitstr++;
  288                 _nbits -= _BITSTR_BITS;
  289         }
  290         while (_nbits >= (int)_BITSTR_BITS) {
  291                 _value += __bitcountl(*_curbitstr);
  292                 _curbitstr++;
  293                 _nbits -= _BITSTR_BITS;
  294         }
  295         if (_nbits > 0) {
  296                 mask = _bit_make_mask(0, _bit_offset(_nbits - 1));
  297                 _value += __bitcountl(*_curbitstr & mask);
  298         }
  299 
  300 out:
  301         *_result = _value;
  302 }
  303 
  304 #endif  /* _SYS_BITSTRING_H_ */

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