dist/pdisk/bitfield.h

   1 //
   2 // bitfield.h - extract and set bit fields
   3 //
   4 // Written by Eryk Vershen
   5 //
   6 // Bitfields are not particularly transportable between big and little
   7 // endian machines.  Big endian machines lay out bitfields starting
   8 // from the most significant bit of the (one, two or four byte) number,
   9 // whereas little endian machines lay out bitfields starting from the
  10 // least signifcant bit.
  11 //
  12 // These routines were written to support some bitfields in a disk
  13 // data structure (partition map) whose original definition was on
  14 // a big-endian machine.
  15 //
  16 // They only work on 32-bit values because I didn't need 16-bit support.
  17 // The bits in the long word are numbered from 0 (least significant) to
  18 // 31 (most significant).
  19 //
  20
  21 /*
  22  * Copyright 1996,1998 by Apple Computer, Inc.
  23  *              All Rights Reserved
  24  *
  25  * Permission to use, copy, modify, and distribute this software and
  26  * its documentation for any purpose and without fee is hereby granted,
  27  * provided that the above copyright notice appears in all copies and
  28  * that both the copyright notice and this permission notice appear in
  29  * supporting documentation.
  30  *
  31  * APPLE COMPUTER DISCLAIMS ALL WARRANTIES WITH REGARD TO THIS SOFTWARE
  32  * INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
  33  * FOR A PARTICULAR PURPOSE.
  34  *
  35  * IN NO EVENT SHALL APPLE COMPUTER BE LIABLE FOR ANY SPECIAL, INDIRECT, OR
  36  * CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM
  37  * LOSS OF USE, DATA OR PROFITS, WHETHER IN ACTION OF CONTRACT,
  38  * NEGLIGENCE, OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION
  39  * WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
  40  */
  41
  42 #ifndef __bitfield__
  43 #define __bitfield__
  44
  45
  46 //
  47 // Defines
  48 //
  49
  50
  51 //
  52 // Types
  53 //
  54
  55
  56 //
  57 // Global Constants
  58 //
  59
  60
  61 //
  62 // Global Variables
  63 //
  64
  65
  66 //
  67 // Forward declarations
  68 //
  69 unsigned long bitfield_set(unsigned long *bf, int base, int length, unsigned long value);
  70 unsigned long bitfield_get(unsigned long bf, int base, int length);
  71
  72 #endif /* __bitfield__ */