osfmk/kern/bits.c

   1 /*
   2  * Copyright (c) 2000 Apple Computer, Inc. All rights reserved.
   3  *
   4  * @APPLE_LICENSE_HEADER_START@
   5  *
   6  * This file contains Original Code and/or Modifications of Original Code
   7  * as defined in and that are subject to the Apple Public Source License
   8  * Version 2.0 (the 'License'). You may not use this file except in
   9  * compliance with the License. Please obtain a copy of the License at
  10  * http://www.opensource.apple.com/apsl/ and read it before using this
  11  * file.
  12  *
  13  * The Original Code and all software distributed under the License are
  14  * distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER
  15  * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
  16  * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
  17  * FITNESS FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT.
  18  * Please see the License for the specific language governing rights and
  19  * limitations under the License.
  20  *
  21  * @APPLE_LICENSE_HEADER_END@
  22  */
  23 /*
  24  * @OSF_COPYRIGHT@
  25  */
  26 /*
  27  * HISTORY
  28  *
  29  * Revision 1.1.1.1  1998/09/22 21:05:35  wsanchez
  30  * Import of Mac OS X kernel (~semeria)
  31  *
  32  * Revision 1.2  1998/04/29 17:35:55  mburg
  33  * MK7.3 merger
  34  *
  35  * Revision 1.1.24.1  1998/02/03  09:27:19  gdt
  36  *      Merge up to MK7.3
  37  *      [1998/02/03  09:12:57  gdt]
  38  *
  39  * Revision 1.1.21.1  1996/11/29  16:57:21  stephen
  40  *      nmklinux_1.0b3_shared into pmk1.1
  41  *      Added explanatory note.
  42  *      [1996/04/10  16:54:46  emcmanus]
  43  *
  44  * Revision 1.1.22.1  1997/06/17  02:57:05  devrcs
  45  *      Added `testbit()' routine.
  46  *      [1996/03/18  15:21:50  rkc]
  47  *
  48  * Revision 1.1.7.3  1995/01/10  05:10:36  devrcs
  49  *      mk6 CR801 - copyright marker not FREE_
  50  *      [1994/12/01  19:24:54  dwm]
  51  *
  52  * Revision 1.1.7.1  1994/06/14  16:59:49  bolinger
  53  *      Merge up to NMK17.2.
  54  *      [1994/06/14  16:53:29  bolinger]
  55  *
  56  * Revision 1.1.5.1  1994/04/11  09:36:31  bernadat
  57  *      Checked in NMK16_2 revision
  58  *      [94/03/15            bernadat]
  59  *
  60  * Revision 1.1.3.1  1993/12/23  08:53:13  bernadat
  61  *      Checked in bolinger_860ci revision.
  62  *      [93/11/29            bernadat]
  63  *
  64  * Revision 1.1.1.2  1993/09/12  15:44:20  bolinger
  65  *      Initial checkin of 860 modifications; MD files from NMK14.8.
  66  *
  67  * $EndLog$
  68  */
  69 /*
  70  * C version of bit manipulation routines now required by kernel.
  71  * Should be replaced with assembler versions in any real port.
  72  *
  73  * Note that these routines use little-endian numbering for bits (i.e.,
  74  * the bit number corresponds to the associated power-of-2).
  75  */
  76 #include <mach/machine/vm_param.h>      /* for BYTE_SIZE */
  77
  78 #define INT_SIZE        (BYTE_SIZE * sizeof (int))
  79
  80 /*
  81  * Set indicated bit in bit string.
  82  */
  83 void
  84 setbit(int bitno, int *s)
  85 {
  86         for ( ; INT_SIZE <= bitno; bitno -= INT_SIZE, ++s)
  87                 ;
  88         *s |= 1 << bitno;
  89 }
  90
  91 /*
  92  * Clear indicated bit in bit string.
  93  */
  94 void
  95 clrbit(int bitno, int *s)
  96 {
  97         for ( ; INT_SIZE <= bitno; bitno -= INT_SIZE, ++s)
  98                 ;
  99         *s &= ~(1 << bitno);
 100 }
 101
 102 /*
 103  * Find first bit set in bit string.
 104  */
 105 int
 106 ffsbit(int *s)
 107 {
 108         int offset, mask;
 109
 110         for (offset = 0; !*s; offset += INT_SIZE, ++s)
 111                 ;
 112         for (mask = 1; mask; mask <<= 1, ++offset)
 113                 if (mask & *s)
 114                         return (offset);
 115         /*
 116          * Shouldn't get here
 117          */
 118         return (0);
 119 }
 120
 121 /*
 122  * Test if indicated bit is set in bit string.
 123  */
 124 int
 125 testbit(int bitno, int *s)
 126 {
 127         for ( ; INT_SIZE <= bitno; bitno -= INT_SIZE, ++s)
 128                 ;
 129         return(*s & (1 << bitno));
 130 }