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  * 4. Neither the name of the University nor the names of its contributors
   17  *    may be used to endorse or promote products derived from this software
   18  *    without specific prior written permission.
   19  *
   20  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
   21  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
   22  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
   23  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
   24  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
   25  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
   26  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
   27  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
   28  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
   29  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
   30  * SUCH DAMAGE.
   31  *
   32  * $FreeBSD: stable/9/sys/sys/bitstring.h 139825 2005-01-07 02:29:27Z imp $
   33  */
   34 
   35 #ifndef _SYS_BITSTRING_H_
   36 #define _SYS_BITSTRING_H_
   37 
   38 typedef unsigned char bitstr_t;
   39 
   40 /* internal macros */
   41                                 /* byte of the bitstring bit is in */
   42 #define _bit_byte(bit) \
   43         ((bit) >> 3)
   44 
   45                                 /* mask for the bit within its byte */
   46 #define _bit_mask(bit) \
   47         (1 << ((bit)&0x7))
   48 
   49 /* external macros */
   50                                 /* bytes in a bitstring of nbits bits */
   51 #define bitstr_size(nbits) \
   52         (((nbits) + 7) >> 3)
   53 
   54                                 /* allocate a bitstring */
   55 #define bit_alloc(nbits) \
   56         (bitstr_t *)calloc((size_t)bitstr_size(nbits), sizeof(bitstr_t))
   57 
   58                                 /* allocate a bitstring on the stack */
   59 #define bit_decl(name, nbits) \
   60         ((name)[bitstr_size(nbits)])
   61 
   62                                 /* is bit N of bitstring name set? */
   63 #define bit_test(name, bit) \
   64         ((name)[_bit_byte(bit)] & _bit_mask(bit))
   65 
   66                                 /* set bit N of bitstring name */
   67 #define bit_set(name, bit) \
   68         ((name)[_bit_byte(bit)] |= _bit_mask(bit))
   69 
   70                                 /* clear bit N of bitstring name */
   71 #define bit_clear(name, bit) \
   72         ((name)[_bit_byte(bit)] &= ~_bit_mask(bit))
   73 
   74                                 /* clear bits start ... stop in bitstring */
   75 #define bit_nclear(name, start, stop) do { \
   76         register bitstr_t *_name = (name); \
   77         register int _start = (start), _stop = (stop); \
   78         register int _startbyte = _bit_byte(_start); \
   79         register int _stopbyte = _bit_byte(_stop); \
   80         if (_startbyte == _stopbyte) { \
   81                 _name[_startbyte] &= ((0xff >> (8 - (_start&0x7))) | \
   82                                       (0xff << ((_stop&0x7) + 1))); \
   83         } else { \
   84                 _name[_startbyte] &= 0xff >> (8 - (_start&0x7)); \
   85                 while (++_startbyte < _stopbyte) \
   86                         _name[_startbyte] = 0; \
   87                 _name[_stopbyte] &= 0xff << ((_stop&0x7) + 1); \
   88         } \
   89 } while (0)
   90 
   91                                 /* set bits start ... stop in bitstring */
   92 #define bit_nset(name, start, stop) do { \
   93         register bitstr_t *_name = (name); \
   94         register int _start = (start), _stop = (stop); \
   95         register int _startbyte = _bit_byte(_start); \
   96         register int _stopbyte = _bit_byte(_stop); \
   97         if (_startbyte == _stopbyte) { \
   98                 _name[_startbyte] |= ((0xff << (_start&0x7)) & \
   99                                     (0xff >> (7 - (_stop&0x7)))); \
  100         } else { \
  101                 _name[_startbyte] |= 0xff << ((_start)&0x7); \
  102                 while (++_startbyte < _stopbyte) \
  103                         _name[_startbyte] = 0xff; \
  104                 _name[_stopbyte] |= 0xff >> (7 - (_stop&0x7)); \
  105         } \
  106 } while (0)
  107 
  108                                 /* find first bit clear in name */
  109 #define bit_ffc(name, nbits, value) do { \
  110         register bitstr_t *_name = (name); \
  111         register int _byte, _nbits = (nbits); \
  112         register int _stopbyte = _bit_byte(_nbits - 1), _value = -1; \
  113         if (_nbits > 0) \
  114                 for (_byte = 0; _byte <= _stopbyte; ++_byte) \
  115                         if (_name[_byte] != 0xff) { \
  116                                 bitstr_t _lb; \
  117                                 _value = _byte << 3; \
  118                                 for (_lb = _name[_byte]; (_lb&0x1); \
  119                                     ++_value, _lb >>= 1); \
  120                                 break; \
  121                         } \
  122         if (_value >= nbits) \
  123                 _value = -1; \
  124         *(value) = _value; \
  125 } while (0)
  126 
  127                                 /* find first bit set in name */
  128 #define bit_ffs(name, nbits, value) do { \
  129         register bitstr_t *_name = (name); \
  130         register int _byte, _nbits = (nbits); \
  131         register int _stopbyte = _bit_byte(_nbits - 1), _value = -1; \
  132         if (_nbits > 0) \
  133                 for (_byte = 0; _byte <= _stopbyte; ++_byte) \
  134                         if (_name[_byte]) { \
  135                                 bitstr_t _lb; \
  136                                 _value = _byte << 3; \
  137                                 for (_lb = _name[_byte]; !(_lb&0x1); \
  138                                     ++_value, _lb >>= 1); \
  139                                 break; \
  140                         } \
  141         if (_value >= nbits) \
  142                 _value = -1; \
  143         *(value) = _value; \
  144 } while (0)
  145 
  146 #endif /* !_SYS_BITSTRING_H_ */

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