projects / thirdparty / man-pages.git / blame
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1 | .\" Copyright 1993 David Metcalfe (david@prism.demon.co.uk) |
| 2 | .\" | |
| 3 | .\" Permission is granted to make and distribute verbatim copies of this | |
| 4 | .\" manual provided the copyright notice and this permission notice are | |
| 5 | .\" preserved on all copies. | |
| 6 | .\" | |
| 7 | .\" Permission is granted to copy and distribute modified versions of this | |
| 8 | .\" manual under the conditions for verbatim copying, provided that the | |
| 9 | .\" entire resulting derived work is distributed under the terms of a | |
| 10 | .\" permission notice identical to this one. | |
| c13182ef | 11 | .\" |
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12 | .\" Since the Linux kernel and libraries are constantly changing, this |
| 13 | .\" manual page may be incorrect or out-of-date. The author(s) assume no | |
| 14 | .\" responsibility for errors or omissions, or for damages resulting from | |
| 15 | .\" the use of the information contained herein. The author(s) may not | |
| 16 | .\" have taken the same level of care in the production of this manual, | |
| 17 | .\" which is licensed free of charge, as they might when working | |
| 18 | .\" professionally. | |
| c13182ef | 19 | .\" |
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20 | .\" Formatted or processed versions of this manual, if unaccompanied by |
| 21 | .\" the source, must acknowledge the copyright and authors of this work. | |
| 22 | .\" | |
| 23 | .\" References consulted: | |
| 24 | .\" Linux libc source code | |
| 25 | .\" Lewine's _POSIX Programmer's Guide_ (O'Reilly & Associates, 1991) | |
| 26 | .\" 386BSD man pages | |
| 27 | .\" Modified Sat Jul 24 19:39:35 1993 by Rik Faith (faith@cs.unc.edu) | |
| 28 | .\" | |
| 29 | .\" Modified 2003 Walter Harms (walter.harms@informatik.uni-oldenburg.de) | |
| c13182ef | 30 | .\" |
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31 | .TH FFS 3 2003-08-05 "GNU" "Linux Programmer's Manual" |
| 32 | .SH NAME | |
| 33 | ffs \- find first bit set in a word | |
| 34 | .SH SYNOPSIS | |
| 35 | .nf | |
| 36 | .B #include <strings.h> | |
| 37 | .sp | |
| 38 | .BI "int ffs(int " i ); | |
| 39 | .sp | |
| 40 | .B #define _GNU_SOURCE | |
| 41 | .br | |
| 42 | .B #include <string.h> | |
| 43 | .sp | |
| 44 | .BI "int ffsl(long int " i ); | |
| 45 | .sp | |
| 46 | .BI "int ffsll(long long int " i ); | |
| 47 | .fi | |
| 48 | .SH DESCRIPTION | |
| 63aa9df0 | 49 | The \fBffs\fP() function returns the position of the first |
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50 | (least significant) bit set in the word \fIi\fP. |
| 51 | The least significant bit is position 1 and the | |
| 52 | most significant position e.g. 32 or 64. | |
| 53 | .BR | |
| 63aa9df0 | 54 | The functions \fBffsll\fP() and \fBffsl\fP() do the same but take |
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55 | arguments of possibly different size. |
| 56 | .SH "RETURN VALUE" | |
| 57 | These functions return the position of the first bit set, | |
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58 | or 0 if no bits are set in |
| 59 | .IR i . | |
| fea681da | 60 | .SH "CONFORMING TO" |
| 68e1685c | 61 | 4.3BSD, POSIX.1-2001. |
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62 | .SH NOTES |
| 63 | BSD systems have a prototype in | |
| 64 | .IR <string.h> . | |
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65 | .SH "SEE ALSO" |
| 66 | .BR feature_test_macros (7) |