projects / thirdparty / man-pages.git / blame
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|---|---|---|
| a1eaacb1 | 1 | '\" t |
| fea681da MK |
2 | .\" Copyright 1993 David Metcalfe (david@prism.demon.co.uk) |
| 3 | .\" | |
| 5fbde956 | 4 | .\" SPDX-License-Identifier: Linux-man-pages-copyleft |
| fea681da MK |
5 | .\" |
| 6 | .\" References consulted: | |
| 7 | .\" Linux libc source code | |
| 8 | .\" Lewine's _POSIX Programmer's Guide_ (O'Reilly & Associates, 1991) | |
| 9 | .\" 386BSD man pages | |
| 10 | .\" Modified Sat Jul 24 19:39:35 1993 by Rik Faith (faith@cs.unc.edu) | |
| 11 | .\" | |
| 12 | .\" Modified 2003 Walter Harms (walter.harms@informatik.uni-oldenburg.de) | |
| c13182ef | 13 | .\" |
| 4c1c5274 | 14 | .TH ffs 3 (date) "Linux man-pages (unreleased)" |
| fea681da | 15 | .SH NAME |
| 81927551 | 16 | ffs, ffsl, ffsll \- find first bit set in a word |
| afa8db94 AC |
17 | .SH LIBRARY |
| 18 | Standard C library | |
| 19 | .RI ( libc ", " \-lc ) | |
| fea681da MK |
20 | .SH SYNOPSIS |
| 21 | .nf | |
| 22 | .B #include <strings.h> | |
| c6d039a3 | 23 | .P |
| fea681da | 24 | .BI "int ffs(int " i ); |
| ae85f653 | 25 | .BI "int ffsl(long " i ); |
| ae85f653 | 26 | .BI "int ffsll(long long " i ); |
| fea681da | 27 | .fi |
| c6d039a3 | 28 | .P |
| d39ad78f | 29 | .RS -4 |
| be403e3d MK |
30 | Feature Test Macro Requirements for glibc (see |
| 31 | .BR feature_test_macros (7)): | |
| d39ad78f | 32 | .RE |
| c6d039a3 | 33 | .P |
| be403e3d | 34 | .BR ffs (): |
| 9d2adbae MK |
35 | .nf |
| 36 | Since glibc 2.12: | |
| 37 | _XOPEN_SOURCE >= 700 | |
| 5c10d2c5 | 38 | || ! (_POSIX_C_SOURCE >= 200809L) |
| 75c018a1 AC |
39 | || /* glibc >= 2.19: */ _DEFAULT_SOURCE |
| 40 | || /* glibc <= 2.19: */ _BSD_SOURCE || _SVID_SOURCE | |
| 9d2adbae MK |
41 | Before glibc 2.12: |
| 42 | none | |
| 43 | .fi | |
| c6d039a3 | 44 | .P |
| be403e3d MK |
45 | .BR ffsl (), |
| 46 | .BR ffsll (): | |
| 9d2adbae MK |
47 | .nf |
| 48 | Since glibc 2.27: | |
| 247bbcf0 | 49 | .\" glibc commit 68fe16dd327c895c08b9ee443b234c49c13b36e9 |
| 9d2adbae MK |
50 | _DEFAULT_SOURCE |
| 51 | Before glibc 2.27: | |
| 52 | _GNU_SOURCE | |
| 53 | .fi | |
| fea681da | 54 | .SH DESCRIPTION |
| 60a90ecd MK |
55 | The |
| 56 | .BR ffs () | |
| 57 | function returns the position of the first | |
| fea681da MK |
58 | (least significant) bit set in the word \fIi\fP. |
| 59 | The least significant bit is position 1 and the | |
| 75b94dc3 | 60 | most significant position is, for example, 32 or 64. |
| 60a90ecd MK |
61 | The functions |
| 62 | .BR ffsll () | |
| 63 | and | |
| 64 | .BR ffsl () | |
| 65 | do the same but take | |
| fea681da | 66 | arguments of possibly different size. |
| 47297adb | 67 | .SH RETURN VALUE |
| fea681da | 68 | These functions return the position of the first bit set, |
| fb84c583 MK |
69 | or 0 if no bits are set in |
| 70 | .IR i . | |
| 7eea6fc3 | 71 | .SH ATTRIBUTES |
| 067fb97f MK |
72 | For an explanation of the terms used in this section, see |
| 73 | .BR attributes (7). | |
| 74 | .TS | |
| 75 | allbox; | |
| c466875e | 76 | lbx lb lb |
| 067fb97f MK |
77 | l l l. |
| 78 | Interface Attribute Value | |
| 79 | T{ | |
| 9e54434e BR |
80 | .na |
| 81 | .nh | |
| 7eea6fc3 PH |
82 | .BR ffs (), |
| 83 | .BR ffsl (), | |
| 7eea6fc3 | 84 | .BR ffsll () |
| 067fb97f MK |
85 | T} Thread safety MT-Safe |
| 86 | .TE | |
| 3113c7f3 | 87 | .SH STANDARDS |
| 4131356c AC |
88 | .TP |
| 89 | .BR ffs () | |
| 6d3452a4 | 90 | POSIX.1-2001, POSIX.1-2008, 4.3BSD. |
| 4131356c | 91 | .TP |
| a385e7d7 | 92 | .BR ffsl () |
| 4131356c | 93 | .TQ |
| a385e7d7 | 94 | .BR ffsll () |
| 4131356c | 95 | GNU. |
| 47297adb | 96 | .SH SEE ALSO |
| 0a4f8b7b | 97 | .BR memchr (3) |