projects / apple / xnu.git / blame
| Commit | Line | Data |
|---|---|---|
| 1c79356b | 1 | /* |
| 5d5c5d0d A |
2 | * Copyright (c) 2000 Apple Computer, Inc. All rights reserved. |
| 3 | * | |
| 2d21ac55 | 4 | * @APPLE_OSREFERENCE_LICENSE_HEADER_START@ |
| 1c79356b | 5 | * |
| 2d21ac55 A |
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. | |
| 8f6c56a5 | 14 | * |
| 2d21ac55 A |
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 | |
| 8f6c56a5 A |
20 | * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES, |
| 21 | * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY, | |
| 2d21ac55 A |
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. | |
| 8f6c56a5 | 25 | * |
| 2d21ac55 | 26 | * @APPLE_OSREFERENCE_LICENSE_HEADER_END@ |
| 1c79356b A |
27 | */ |
| 28 | /* Copyright (c) 1991 NeXT Computer, Inc. All rights reserved. | |
| 29 | * | |
| 30 | * File: machdep/i386/libc/ffs.c | |
| 31 | * Author: Bruce Martin, NeXT Computer, Inc. | |
| 32 | * | |
| 33 | * This file contains machine dependent code for the ffs function | |
| 34 | * on NeXT i386-based products. Currently tuned for the i486. | |
| 35 | * | |
| 36 | * HISTORY | |
| 37 | * 27-Sep-92 Bruce Martin (Bruce_Martin@NeXT.COM) | |
| 38 | * Created: stolen from Mike's code. | |
| 39 | */ | |
| 40 | ||
| 41 | unsigned | |
| 42 | ffs(unsigned mask) | |
| 43 | { | |
| 44 | unsigned bitpos; | |
| 45 | ||
| 46 | if (mask == 0) | |
| 47 | return 0; | |
| 48 | ||
| 49 | bitpos = 1; | |
| 50 | while ((mask & 0xff) == 0) { | |
| 51 | bitpos += 8; | |
| 52 | mask >>= 8; | |
| 53 | } | |
| 54 | while ((mask & 1) == 0) { | |
| 55 | bitpos += 1; | |
| 56 | mask >>= 1; | |
| 57 | } | |
| 58 | return bitpos; | |
| 59 | } |