osfmk/kern/bits.c

   1 /*
   2  * Copyright (c) 2000 Apple Computer, Inc. All rights reserved.
   3  *
   4  * @APPLE_LICENSE_HEADER_START@
   5  *
   6  * Copyright (c) 1999-2003 Apple Computer, Inc.  All Rights Reserved.
   7  *
   8  * This file contains Original Code and/or Modifications of Original Code
   9  * as defined in and that are subject to the Apple Public Source License
  10  * Version 2.0 (the 'License'). You may not use this file except in
  11  * compliance with the License. Please obtain a copy of the License at
  12  * http://www.opensource.apple.com/apsl/ and read it before using this
  13  * file.
  14  *
  15  * The Original Code and all software distributed under the License are
  16  * distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER
  17  * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
  18  * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
  19  * FITNESS FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT.
  20  * Please see the License for the specific language governing rights and
  21  * limitations under the License.
  22  *
  23  * @APPLE_LICENSE_HEADER_END@
  24  */
  25 /*
  26  * @OSF_COPYRIGHT@
  27  */
  28 /*
  29  * HISTORY
  30  *
  31  * Revision 1.1.1.1  1998/09/22 21:05:35  wsanchez
  32  * Import of Mac OS X kernel (~semeria)
  33  *
  34  * Revision 1.2  1998/04/29 17:35:55  mburg
  35  * MK7.3 merger
  36  *
  37  * Revision 1.1.24.1  1998/02/03  09:27:19  gdt
  38  *      Merge up to MK7.3
  39  *      [1998/02/03  09:12:57  gdt]
  40  *
  41  * Revision 1.1.21.1  1996/11/29  16:57:21  stephen
  42  *      nmklinux_1.0b3_shared into pmk1.1
  43  *      Added explanatory note.
  44  *      [1996/04/10  16:54:46  emcmanus]
  45  *
  46  * Revision 1.1.22.1  1997/06/17  02:57:05  devrcs
  47  *      Added `testbit()' routine.
  48  *      [1996/03/18  15:21:50  rkc]
  49  *
  50  * Revision 1.1.7.3  1995/01/10  05:10:36  devrcs
  51  *      mk6 CR801 - copyright marker not FREE_
  52  *      [1994/12/01  19:24:54  dwm]
  53  *
  54  * Revision 1.1.7.1  1994/06/14  16:59:49  bolinger
  55  *      Merge up to NMK17.2.
  56  *      [1994/06/14  16:53:29  bolinger]
  57  *
  58  * Revision 1.1.5.1  1994/04/11  09:36:31  bernadat
  59  *      Checked in NMK16_2 revision
  60  *      [94/03/15            bernadat]
  61  *
  62  * Revision 1.1.3.1  1993/12/23  08:53:13  bernadat
  63  *      Checked in bolinger_860ci revision.
  64  *      [93/11/29            bernadat]
  65  *
  66  * Revision 1.1.1.2  1993/09/12  15:44:20  bolinger
  67  *      Initial checkin of 860 modifications; MD files from NMK14.8.
  68  *
  69  * $EndLog$
  70  */
  71 /*
  72  * C version of bit manipulation routines now required by kernel.
  73  * Should be replaced with assembler versions in any real port.
  74  *
  75  * Note that these routines use little-endian numbering for bits (i.e.,
  76  * the bit number corresponds to the associated power-of-2).
  77  */
  78 #include <mach/machine/vm_param.h>      /* for BYTE_SIZE */
  79
  80 #define INT_SIZE        (BYTE_SIZE * sizeof (int))
  81
  82 /*
  83  * Set indicated bit in bit string.
  84  */
  85 void
  86 setbit(int bitno, int *s)
  87 {
  88         for ( ; INT_SIZE <= bitno; bitno -= INT_SIZE, ++s)
  89                 ;
  90         *s |= 1 << bitno;
  91 }
  92
  93 /*
  94  * Clear indicated bit in bit string.
  95  */
  96 void
  97 clrbit(int bitno, int *s)
  98 {
  99         for ( ; INT_SIZE <= bitno; bitno -= INT_SIZE, ++s)
 100                 ;
 101         *s &= ~(1 << bitno);
 102 }
 103
 104 /*
 105  * Find first bit set in bit string.
 106  */
 107 int
 108 ffsbit(int *s)
 109 {
 110         int offset, mask;
 111
 112         for (offset = 0; !*s; offset += INT_SIZE, ++s)
 113                 ;
 114         for (mask = 1; mask; mask <<= 1, ++offset)
 115                 if (mask & *s)
 116                         return (offset);
 117         /*
 118          * Shouldn't get here
 119          */
 120         return (0);
 121 }
 122
 123 /*
 124  * Test if indicated bit is set in bit string.
 125  */
 126 int
 127 testbit(int bitno, int *s)
 128 {
 129         for ( ; INT_SIZE <= bitno; bitno -= INT_SIZE, ++s)
 130                 ;
 131         return(*s & (1 << bitno));
 132 }