osfmk/kern/bits.c

   1 /*
   2  * Copyright (c) 2000 Apple Computer, Inc. All rights reserved.
   3  *
   4  * @APPLE_LICENSE_HEADER_START@
   5  *
   6  * The contents of this file constitute Original Code as defined in and
   7  * are subject to the Apple Public Source License Version 1.1 (the
   8  * "License").  You may not use this file except in compliance with the
   9  * License.  Please obtain a copy of the License at
  10  * http://www.apple.com/publicsource and read it before using this file.
  11  *
  12  * This Original Code and all software distributed under the License are
  13  * distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY KIND, EITHER
  14  * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
  15  * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
  16  * FITNESS FOR A PARTICULAR PURPOSE OR NON-INFRINGEMENT.  Please see the
  17  * License for the specific language governing rights and limitations
  18  * under the License.
  19  *
  20  * @APPLE_LICENSE_HEADER_END@
  21  */
  22 /*
  23  * @OSF_COPYRIGHT@
  24  */
  25 /*
  26  * HISTORY
  27  *
  28  * Revision 1.1.1.1  1998/09/22 21:05:35  wsanchez
  29  * Import of Mac OS X kernel (~semeria)
  30  *
  31  * Revision 1.2  1998/04/29 17:35:55  mburg
  32  * MK7.3 merger
  33  *
  34  * Revision 1.1.24.1  1998/02/03  09:27:19  gdt
  35  *      Merge up to MK7.3
  36  *      [1998/02/03  09:12:57  gdt]
  37  *
  38  * Revision 1.1.21.1  1996/11/29  16:57:21  stephen
  39  *      nmklinux_1.0b3_shared into pmk1.1
  40  *      Added explanatory note.
  41  *      [1996/04/10  16:54:46  emcmanus]
  42  *
  43  * Revision 1.1.22.1  1997/06/17  02:57:05  devrcs
  44  *      Added `testbit()' routine.
  45  *      [1996/03/18  15:21:50  rkc]
  46  *
  47  * Revision 1.1.7.3  1995/01/10  05:10:36  devrcs
  48  *      mk6 CR801 - copyright marker not FREE_
  49  *      [1994/12/01  19:24:54  dwm]
  50  *
  51  * Revision 1.1.7.1  1994/06/14  16:59:49  bolinger
  52  *      Merge up to NMK17.2.
  53  *      [1994/06/14  16:53:29  bolinger]
  54  *
  55  * Revision 1.1.5.1  1994/04/11  09:36:31  bernadat
  56  *      Checked in NMK16_2 revision
  57  *      [94/03/15            bernadat]
  58  *
  59  * Revision 1.1.3.1  1993/12/23  08:53:13  bernadat
  60  *      Checked in bolinger_860ci revision.
  61  *      [93/11/29            bernadat]
  62  *
  63  * Revision 1.1.1.2  1993/09/12  15:44:20  bolinger
  64  *      Initial checkin of 860 modifications; MD files from NMK14.8.
  65  *
  66  * $EndLog$
  67  */
  68 /*
  69  * C version of bit manipulation routines now required by kernel.
  70  * Should be replaced with assembler versions in any real port.
  71  *
  72  * Note that these routines use little-endian numbering for bits (i.e.,
  73  * the bit number corresponds to the associated power-of-2).
  74  */
  75 #include <mach/machine/vm_param.h>      /* for BYTE_SIZE */
  76
  77 #define INT_SIZE        (BYTE_SIZE * sizeof (int))
  78
  79 /*
  80  * Set indicated bit in bit string.
  81  */
  82 void
  83 setbit(int bitno, int *s)
  84 {
  85         for ( ; INT_SIZE <= bitno; bitno -= INT_SIZE, ++s)
  86                 ;
  87         *s |= 1 << bitno;
  88 }
  89
  90 /*
  91  * Clear indicated bit in bit string.
  92  */
  93 void
  94 clrbit(int bitno, int *s)
  95 {
  96         for ( ; INT_SIZE <= bitno; bitno -= INT_SIZE, ++s)
  97                 ;
  98         *s &= ~(1 << bitno);
  99 }
 100
 101 /*
 102  * Find first bit set in bit string.
 103  */
 104 int
 105 ffsbit(int *s)
 106 {
 107         int offset, mask;
 108
 109         for (offset = 0; !*s; offset += INT_SIZE, ++s)
 110                 ;
 111         for (mask = 1; mask; mask <<= 1, ++offset)
 112                 if (mask & *s)
 113                         return (offset);
 114         /*
 115          * Shouldn't get here
 116          */
 117         return (0);
 118 }
 119
 120 /*
 121  * Test if indicated bit is set in bit string.
 122  */
 123 int
 124 testbit(int bitno, int *s)
 125 {
 126         for ( ; INT_SIZE <= bitno; bitno -= INT_SIZE, ++s)
 127                 ;
 128         return(*s & (1 << bitno));
 129 }