projects / apple / xnu.git / blame
| Commit | Line | Data |
|---|---|---|
| 1c79356b A |
1 | /* |
| 2 | * Copyright (c) 2000 Apple Computer, Inc. All rights reserved. | |
| 3 | * | |
| 4 | * @APPLE_LICENSE_HEADER_START@ | |
| 5 | * | |
| 43866e37 | 6 | * Copyright (c) 1999-2003 Apple Computer, Inc. All Rights Reserved. |
| 1c79356b | 7 | * |
| 43866e37 A |
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 | |
| 1c79356b A |
17 | * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES, |
| 18 | * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY, | |
| 43866e37 A |
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. | |
| 1c79356b A |
22 | * |
| 23 | * @APPLE_LICENSE_HEADER_END@ | |
| 24 | */ | |
| 25 | /* Copyright (c) 1991 NeXT Computer, Inc. All rights reserved. | |
| 26 | * | |
| 27 | * File: machdep/i386/libc/ffs.c | |
| 28 | * Author: Bruce Martin, NeXT Computer, Inc. | |
| 29 | * | |
| 30 | * This file contains machine dependent code for the ffs function | |
| 31 | * on NeXT i386-based products. Currently tuned for the i486. | |
| 32 | * | |
| 33 | * HISTORY | |
| 34 | * 27-Sep-92 Bruce Martin (Bruce_Martin@NeXT.COM) | |
| 35 | * Created: stolen from Mike's code. | |
| 36 | */ | |
| 37 | ||
| 38 | unsigned | |
| 39 | ffs(unsigned mask) | |
| 40 | { | |
| 41 | unsigned bitpos; | |
| 42 | ||
| 43 | if (mask == 0) | |
| 44 | return 0; | |
| 45 | ||
| 46 | bitpos = 1; | |
| 47 | while ((mask & 0xff) == 0) { | |
| 48 | bitpos += 8; | |
| 49 | mask >>= 8; | |
| 50 | } | |
| 51 | while ((mask & 1) == 0) { | |
| 52 | bitpos += 1; | |
| 53 | mask >>= 1; | |
| 54 | } | |
| 55 | return bitpos; | |
| 56 | } |