osfmk/kern/bits.c

   1 /*
   2  * Copyright (c) 2000 Apple Computer, Inc. All rights reserved.
   3  *
   4  * @APPLE_OSREFERENCE_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. The rights granted to you under the License
  10  * may not be used to create, or enable the creation or redistribution of,
  11  * unlawful or unlicensed copies of an Apple operating system, or to
  12  * circumvent, violate, or enable the circumvention or violation of, any
  13  * terms of an Apple operating system software license agreement.
  14  *
  15  * Please obtain a copy of the License at
  16  * http://www.opensource.apple.com/apsl/ and read it before using this file.
  17  *
  18  * The Original Code and all software distributed under the License are
  19  * distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER
  20  * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
  21  * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
  22  * FITNESS FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT.
  23  * Please see the License for the specific language governing rights and
  24  * limitations under the License.
  25  *
  26  * @APPLE_OSREFERENCE_LICENSE_HEADER_END@
  27  */
  28 /*
  29  * @OSF_COPYRIGHT@
  30  */
  31 /*
  32  * HISTORY
  33  *
  34  * Revision 1.1.1.1  1998/09/22 21:05:35  wsanchez
  35  * Import of Mac OS X kernel (~semeria)
  36  *
  37  * Revision 1.2  1998/04/29 17:35:55  mburg
  38  * MK7.3 merger
  39  *
  40  * Revision 1.1.24.1  1998/02/03  09:27:19  gdt
  41  *      Merge up to MK7.3
  42  *      [1998/02/03  09:12:57  gdt]
  43  *
  44  * Revision 1.1.21.1  1996/11/29  16:57:21  stephen
  45  *      nmklinux_1.0b3_shared into pmk1.1
  46  *      Added explanatory note.
  47  *      [1996/04/10  16:54:46  emcmanus]
  48  *
  49  * Revision 1.1.22.1  1997/06/17  02:57:05  devrcs
  50  *      Added `testbit()' routine.
  51  *      [1996/03/18  15:21:50  rkc]
  52  *
  53  * Revision 1.1.7.3  1995/01/10  05:10:36  devrcs
  54  *      mk6 CR801 - copyright marker not FREE_
  55  *      [1994/12/01  19:24:54  dwm]
  56  *
  57  * Revision 1.1.7.1  1994/06/14  16:59:49  bolinger
  58  *      Merge up to NMK17.2.
  59  *      [1994/06/14  16:53:29  bolinger]
  60  *
  61  * Revision 1.1.5.1  1994/04/11  09:36:31  bernadat
  62  *      Checked in NMK16_2 revision
  63  *      [94/03/15            bernadat]
  64  *
  65  * Revision 1.1.3.1  1993/12/23  08:53:13  bernadat
  66  *      Checked in bolinger_860ci revision.
  67  *      [93/11/29            bernadat]
  68  *
  69  * Revision 1.1.1.2  1993/09/12  15:44:20  bolinger
  70  *      Initial checkin of 860 modifications; MD files from NMK14.8.
  71  *
  72  * $EndLog$
  73  */
  74 /*
  75  * C version of bit manipulation routines now required by kernel.
  76  * Should be replaced with assembler versions in any real port.
  77  *
  78  * Note that these routines use little-endian numbering for bits (i.e.,
  79  * the bit number corresponds to the associated power-of-2).
  80  */
  81 #include <mach/machine/vm_param.h>      /* for BYTE_SIZE */
  82
  83 #define INT_SIZE        (BYTE_SIZE * sizeof (int))
  84
  85 /*
  86  * Set indicated bit in bit string.
  87  */
  88 void
  89 setbit(int bitno, int *s)
  90 {
  91         for ( ; INT_SIZE <= bitno; bitno -= INT_SIZE, ++s)
  92                 ;
  93         *s |= 1 << bitno;
  94 }
  95
  96 /*
  97  * Clear indicated bit in bit string.
  98  */
  99 void
 100 clrbit(int bitno, int *s)
 101 {
 102         for ( ; INT_SIZE <= bitno; bitno -= INT_SIZE, ++s)
 103                 ;
 104         *s &= ~(1 << bitno);
 105 }
 106
 107 /*
 108  * Find first bit set in bit string.
 109  */
 110 int
 111 ffsbit(int *s)
 112 {
 113         int offset, mask;
 114
 115         for (offset = 0; !*s; offset += INT_SIZE, ++s)
 116                 ;
 117         for (mask = 1; mask; mask <<= 1, ++offset)
 118                 if (mask & *s)
 119                         return (offset);
 120         /*
 121          * Shouldn't get here
 122          */
 123         return (0);
 124 }
 125
 126 /*
 127  * Test if indicated bit is set in bit string.
 128  */
 129 int
 130 testbit(int bitno, int *s)
 131 {
 132         for ( ; INT_SIZE <= bitno; bitno -= INT_SIZE, ++s)
 133                 ;
 134         return(*s & (1 << bitno));
 135 }