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c11b1abf | 1 | .\" Copyright (c) 2007 by Michael Kerrisk <mtk.manpages@gmail.com> |
d6d74fd8 | 2 | .\" |
93015253 | 3 | .\" %%%LICENSE_START(VERBATIM) |
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4 | .\" Permission is granted to make and distribute verbatim copies of this |
5 | .\" manual provided the copyright notice and this permission notice are | |
6 | .\" preserved on all copies. | |
7 | .\" | |
8 | .\" Permission is granted to copy and distribute modified versions of this | |
9 | .\" manual under the conditions for verbatim copying, provided that the | |
10 | .\" entire resulting derived work is distributed under the terms of a | |
11 | .\" permission notice identical to this one. | |
12 | .\" | |
13 | .\" Since the Linux kernel and libraries are constantly changing, this | |
14 | .\" manual page may be incorrect or out-of-date. The author(s) assume no | |
15 | .\" responsibility for errors or omissions, or for damages resulting from | |
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16 | .\" the use of the information contained herein. The author(s) may not |
17 | .\" have taken the same level of care in the production of this manual, | |
18 | .\" which is licensed free of charge, as they might when working | |
19 | .\" professionally. | |
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20 | .\" |
21 | .\" Formatted or processed versions of this manual, if unaccompanied by | |
22 | .\" the source, must acknowledge the copyright and authors of this work. | |
4b72fb64 | 23 | .\" %%%LICENSE_END |
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24 | .\" |
25 | .\" 2007-07-31, mtk, Created | |
26 | .\" | |
513051f7 | 27 | .TH TIMERADD 3 2010-02-25 "Linux" "Linux Programmer's Manual" |
d6d74fd8 | 28 | .SH NAME |
93d67152 | 29 | timeradd, timersub, timercmp, timerclear, timerisset \- timeval operations |
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30 | .SH SYNOPSIS |
31 | .nf | |
32 | .B #include <sys/time.h> | |
33 | ||
34 | .BI "void timeradd(struct timeval *" a ", struct timeval *" b , | |
35 | .BI " struct timeval *" res ); | |
36 | ||
37 | .BI "void timersub(struct timeval *" a ", struct timeval *" b , | |
38 | .BI " struct timeval *" res ); | |
39 | ||
40 | .BI "void timerclear(struct timeval *" tvp ); | |
41 | ||
f6c92d2a | 42 | .BI "int timerisset(struct timeval *" tvp ); |
d6d74fd8 | 43 | |
f6c92d2a | 44 | .BI "int timercmp(struct timeval *" a ", struct timeval *" b ", " CMP ); |
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45 | .fi |
46 | .sp | |
47 | .in -4n | |
48 | Feature Test Macro Requirements for glibc (see | |
49 | .BR feature_test_macros (7)): | |
50 | .in | |
51 | .sp | |
cfc2d88d | 52 | All functions shown above: |
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53 | _BSD_SOURCE |
54 | .SH DESCRIPTION | |
55 | The macros are provided to operate on | |
56 | .I timeval | |
57 | structures, defined in | |
0daa9e92 | 58 | .I <sys/time.h> |
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59 | as: |
60 | .sp | |
088a639b | 61 | .in +4n |
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62 | .nf |
63 | struct timeval { | |
64 | time_t tv_sec; /* seconds */ | |
65 | suseconds_t tv_usec; /* microseconds */ | |
66 | }; | |
67 | .fi | |
088a639b | 68 | .in |
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69 | .PP |
70 | .BR timeradd () | |
71 | adds the time values in | |
72 | .I a | |
73 | and | |
74 | .IR b , | |
75 | and places the sum in the | |
76 | .I timeval | |
77 | pointed to by | |
78 | .IR res . | |
79 | The result is normalized such that | |
94e9d9fe | 80 | .I res\->tv_usec |
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81 | has a value in the range 0 to 999,999. |
82 | ||
83 | .BR timersub () | |
93d67152 | 84 | subtracts the time value in |
d6d74fd8 | 85 | .I b |
93d67152 | 86 | from the time value in |
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87 | .IR a , |
88 | and places the result in the | |
89 | .I timeval | |
90 | pointed to by | |
91 | .IR res . | |
92 | The result is normalized such that | |
94e9d9fe | 93 | .I res\->tv_usec |
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94 | has a value in the range 0 to 999,999. |
95 | ||
96 | .BR timerclear () | |
7b01461a | 97 | zeros out the |
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98 | .I timeval |
99 | structure pointed to by | |
100 | .IR tvp , | |
f49c451a | 101 | so that it represents the Epoch: 1970-01-01 00:00:00 +0000 (UTC). |
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102 | |
103 | .BR timerisset () | |
c7094399 | 104 | returns true (nonzero) if either field of the |
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105 | .I timeval |
106 | structure pointed to by | |
0daa9e92 | 107 | .I tvp |
c7094399 | 108 | contains a nonzero value. |
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109 | |
110 | .BR timercmp () | |
111 | compares the timer values in | |
112 | .I a | |
113 | and | |
0daa9e92 | 114 | .I b |
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115 | using the comparison operator |
116 | .IR CMP , | |
c7094399 | 117 | and returns true (nonzero) or false (0) depending on |
d6d74fd8 | 118 | the result of the comparison. |
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119 | Some systems (but not Linux/glibc), |
120 | have a broken | |
121 | .BR timercmp () | |
122 | implementation, | |
123 | .\" HP-UX, Tru64, Irix have a definition like: | |
124 | .\"#define timercmp(tvp, uvp, cmp) \ | |
125 | .\" ((tvp)->tv_sec cmp (uvp)->tv_sec || \ | |
126 | .\" (tvp)->tv_sec == (uvp)->tv_sec && (tvp)->tv_usec cmp (uvp)->tv_usec) | |
127 | in which | |
128 | .I CMP | |
129 | of | |
130 | .IR >= , | |
131 | .IR <= , | |
132 | and | |
133 | .I == | |
134 | do not work; | |
135 | portable applications can instead use | |
136 | ||
137 | !timercmp(..., <) | |
138 | !timercmp(..., >) | |
139 | !timercmp(..., !=) | |
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140 | .SH RETURN VALUE |
141 | .BR timerisset () | |
142 | and | |
143 | .BR timercmp () | |
c7094399 | 144 | return true (nonzero) or false (0). |
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145 | .SH ERRORS |
146 | No errors are defined. | |
147 | .SH CONFORMING TO | |
7aecd4d8 | 148 | Not in POSIX.1. |
d6d74fd8 | 149 | Present on most BSD derivatives. |
47297adb | 150 | .SH SEE ALSO |
d6d74fd8 | 151 | .BR gettimeofday (2), |
f0c34053 | 152 | .BR time (7) |