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  * Copyright (c) 1989, 1993
    3  *      The Regents of the University of California.  All rights reserved.
    4  *
    5  * This code is derived from software contributed to Berkeley by
    6  * Paul Vixie.
    7  *
    8  * Redistribution and use in source and binary forms, with or without
    9  * modification, are permitted provided that the following conditions
   10  * are met:
   11  * 1. Redistributions of source code must retain the above copyright
   12  *    notice, this list of conditions and the following disclaimer.
   13  * 2. Redistributions in binary form must reproduce the above copyright
   14  *    notice, this list of conditions and the following disclaimer in the
   15  *    documentation and/or other materials provided with the distribution.
   16  * 3. All advertising materials mentioning features or use of this software
   17  *    must display the following acknowledgement:
   18  *      This product includes software developed by the University of
   19  *      California, Berkeley and its contributors.
   20  * 4. Neither the name of the University nor the names of its contributors
   21  *    may be used to endorse or promote products derived from this software
   22  *    without specific prior written permission.
   23  *
   24  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
   25  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
   26  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
   27  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
   28  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
   29  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
   30  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
   31  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
   32  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
   33  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
   34  * SUCH DAMAGE.
   35  *
   36  * $FreeBSD: src/sys/sys/bitstring.h,v 1.3 2003/06/13 19:40:13 phk Exp $
   37  */
   38 
   39 #ifndef _SYS_BITSTRING_H_
   40 #define _SYS_BITSTRING_H_
   41 
   42 typedef unsigned char bitstr_t;
   43 
   44 /* internal macros */
   45                                 /* byte of the bitstring bit is in */
   46 #define _bit_byte(bit) \
   47         ((bit) >> 3)
   48 
   49                                 /* mask for the bit within its byte */
   50 #define _bit_mask(bit) \
   51         (1 << ((bit)&0x7))
   52 
   53 /* external macros */
   54                                 /* bytes in a bitstring of nbits bits */
   55 #define bitstr_size(nbits) \
   56         (((nbits) + 7) >> 3)
   57 
   58                                 /* allocate a bitstring */
   59 #define bit_alloc(nbits) \
   60         (bitstr_t *)calloc((size_t)bitstr_size(nbits), sizeof(bitstr_t))
   61 
   62                                 /* allocate a bitstring on the stack */
   63 #define bit_decl(name, nbits) \
   64         ((name)[bitstr_size(nbits)])
   65 
   66                                 /* is bit N of bitstring name set? */
   67 #define bit_test(name, bit) \
   68         ((name)[_bit_byte(bit)] & _bit_mask(bit))
   69 
   70                                 /* set bit N of bitstring name */
   71 #define bit_set(name, bit) \
   72         ((name)[_bit_byte(bit)] |= _bit_mask(bit))
   73 
   74                                 /* clear bit N of bitstring name */
   75 #define bit_clear(name, bit) \
   76         ((name)[_bit_byte(bit)] &= ~_bit_mask(bit))
   77 
   78                                 /* clear bits start ... stop in bitstring */
   79 #define bit_nclear(name, start, stop) do { \
   80         register bitstr_t *_name = (name); \
   81         register int _start = (start), _stop = (stop); \
   82         register int _startbyte = _bit_byte(_start); \
   83         register int _stopbyte = _bit_byte(_stop); \
   84         if (_startbyte == _stopbyte) { \
   85                 _name[_startbyte] &= ((0xff >> (8 - (_start&0x7))) | \
   86                                       (0xff << ((_stop&0x7) + 1))); \
   87         } else { \
   88                 _name[_startbyte] &= 0xff >> (8 - (_start&0x7)); \
   89                 while (++_startbyte < _stopbyte) \
   90                         _name[_startbyte] = 0; \
   91                 _name[_stopbyte] &= 0xff << ((_stop&0x7) + 1); \
   92         } \
   93 } while (0)
   94 
   95                                 /* set bits start ... stop in bitstring */
   96 #define bit_nset(name, start, stop) do { \
   97         register bitstr_t *_name = (name); \
   98         register int _start = (start), _stop = (stop); \
   99         register int _startbyte = _bit_byte(_start); \
  100         register int _stopbyte = _bit_byte(_stop); \
  101         if (_startbyte == _stopbyte) { \
  102                 _name[_startbyte] |= ((0xff << (_start&0x7)) & \
  103                                     (0xff >> (7 - (_stop&0x7)))); \
  104         } else { \
  105                 _name[_startbyte] |= 0xff << ((_start)&0x7); \
  106                 while (++_startbyte < _stopbyte) \
  107                         _name[_startbyte] = 0xff; \
  108                 _name[_stopbyte] |= 0xff >> (7 - (_stop&0x7)); \
  109         } \
  110 } while (0)
  111 
  112                                 /* find first bit clear in name */
  113 #define bit_ffc(name, nbits, value) do { \
  114         register bitstr_t *_name = (name); \
  115         register int _byte, _nbits = (nbits); \
  116         register int _stopbyte = _bit_byte(_nbits - 1), _value = -1; \
  117         if (_nbits > 0) \
  118                 for (_byte = 0; _byte <= _stopbyte; ++_byte) \
  119                         if (_name[_byte] != 0xff) { \
  120                                 bitstr_t _lb; \
  121                                 _value = _byte << 3; \
  122                                 for (_lb = _name[_byte]; (_lb&0x1); \
  123                                     ++_value, _lb >>= 1); \
  124                                 break; \
  125                         } \
  126         if (_value >= nbits) \
  127                 _value = -1; \
  128         *(value) = _value; \
  129 } while (0)
  130 
  131                                 /* find first bit set in name */
  132 #define bit_ffs(name, nbits, value) do { \
  133         register bitstr_t *_name = (name); \
  134         register int _byte, _nbits = (nbits); \
  135         register int _stopbyte = _bit_byte(_nbits - 1), _value = -1; \
  136         if (_nbits > 0) \
  137                 for (_byte = 0; _byte <= _stopbyte; ++_byte) \
  138                         if (_name[_byte]) { \
  139                                 bitstr_t _lb; \
  140                                 _value = _byte << 3; \
  141                                 for (_lb = _name[_byte]; !(_lb&0x1); \
  142                                     ++_value, _lb >>= 1); \
  143                                 break; \
  144                         } \
  145         if (_value >= nbits) \
  146                 _value = -1; \
  147         *(value) = _value; \
  148 } while (0)
  149 
  150 #endif /* !_SYS_BITSTRING_H_ */

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