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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 |
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8 | .\" Permission is granted to copy and distribute modified versions of this | |
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10 | .\" entire resulting derived work is distributed under the terms of a | |
11 | .\" permission notice identical to this one. | |
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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14 | .\" manual page may be incorrect or out-of-date.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 | .\" | |
4b8c67d9 | 27 | .TH TIMERADD 3 2017-09-15 "Linux" "Linux Programmer's Manual" |
d6d74fd8 | 28 | .SH NAME |
93d67152 | 29 | timeradd, timersub, timercmp, timerclear, timerisset \- timeval operations |
d6d74fd8 MK |
30 | .SH SYNOPSIS |
31 | .nf | |
32 | .B #include <sys/time.h> | |
dbfe9c70 | 33 | .PP |
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34 | .BI "void timeradd(struct timeval *" a ", struct timeval *" b , |
35 | .BI " struct timeval *" res ); | |
dbfe9c70 | 36 | .PP |
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37 | .BI "void timersub(struct timeval *" a ", struct timeval *" b , |
38 | .BI " struct timeval *" res ); | |
dbfe9c70 | 39 | .PP |
d6d74fd8 | 40 | .BI "void timerclear(struct timeval *" tvp ); |
dbfe9c70 | 41 | .PP |
f6c92d2a | 42 | .BI "int timerisset(struct timeval *" tvp ); |
dbfe9c70 | 43 | .PP |
f6c92d2a | 44 | .BI "int timercmp(struct timeval *" a ", struct timeval *" b ", " CMP ); |
d6d74fd8 | 45 | .fi |
68e4db0a | 46 | .PP |
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47 | .in -4n |
48 | Feature Test Macro Requirements for glibc (see | |
49 | .BR feature_test_macros (7)): | |
50 | .in | |
68e4db0a | 51 | .PP |
cfc2d88d | 52 | All functions shown above: |
51c612fb MK |
53 | Since glibc 2.19: |
54 | _DEFAULT_SOURCE | |
55 | Glibc 2.19 and earlier: | |
56 | _BSD_SOURCE | |
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57 | .SH DESCRIPTION |
58 | The macros are provided to operate on | |
59 | .I timeval | |
60 | structures, defined in | |
0daa9e92 | 61 | .I <sys/time.h> |
d6d74fd8 | 62 | as: |
51f5698d | 63 | .PP |
088a639b | 64 | .in +4n |
bdd915e2 | 65 | .EX |
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66 | struct timeval { |
67 | time_t tv_sec; /* seconds */ | |
68 | suseconds_t tv_usec; /* microseconds */ | |
69 | }; | |
bdd915e2 | 70 | .EE |
088a639b | 71 | .in |
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72 | .PP |
73 | .BR timeradd () | |
74 | adds the time values in | |
75 | .I a | |
76 | and | |
77 | .IR b , | |
78 | and places the sum in the | |
79 | .I timeval | |
80 | pointed to by | |
81 | .IR res . | |
82 | The result is normalized such that | |
94e9d9fe | 83 | .I res\->tv_usec |
d6d74fd8 | 84 | has a value in the range 0 to 999,999. |
847e0d88 | 85 | .PP |
d6d74fd8 | 86 | .BR timersub () |
93d67152 | 87 | subtracts the time value in |
d6d74fd8 | 88 | .I b |
93d67152 | 89 | from the time value in |
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90 | .IR a , |
91 | and places the result in the | |
92 | .I timeval | |
93 | pointed to by | |
94 | .IR res . | |
95 | The result is normalized such that | |
94e9d9fe | 96 | .I res\->tv_usec |
d6d74fd8 | 97 | has a value in the range 0 to 999,999. |
847e0d88 | 98 | .PP |
d6d74fd8 | 99 | .BR timerclear () |
7b01461a | 100 | zeros out the |
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101 | .I timeval |
102 | structure pointed to by | |
103 | .IR tvp , | |
f49c451a | 104 | so that it represents the Epoch: 1970-01-01 00:00:00 +0000 (UTC). |
847e0d88 | 105 | .PP |
d6d74fd8 | 106 | .BR timerisset () |
c7094399 | 107 | returns true (nonzero) if either field of the |
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108 | .I timeval |
109 | structure pointed to by | |
0daa9e92 | 110 | .I tvp |
c7094399 | 111 | contains a nonzero value. |
847e0d88 | 112 | .PP |
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113 | .BR timercmp () |
114 | compares the timer values in | |
115 | .I a | |
116 | and | |
0daa9e92 | 117 | .I b |
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118 | using the comparison operator |
119 | .IR CMP , | |
c7094399 | 120 | and returns true (nonzero) or false (0) depending on |
d6d74fd8 | 121 | the result of the comparison. |
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122 | Some systems (but not Linux/glibc), |
123 | have a broken | |
124 | .BR timercmp () | |
125 | implementation, | |
126 | .\" HP-UX, Tru64, Irix have a definition like: | |
127 | .\"#define timercmp(tvp, uvp, cmp) \ | |
128 | .\" ((tvp)->tv_sec cmp (uvp)->tv_sec || \ | |
129 | .\" (tvp)->tv_sec == (uvp)->tv_sec && (tvp)->tv_usec cmp (uvp)->tv_usec) | |
130 | in which | |
131 | .I CMP | |
132 | of | |
133 | .IR >= , | |
134 | .IR <= , | |
135 | and | |
136 | .I == | |
137 | do not work; | |
138 | portable applications can instead use | |
847e0d88 | 139 | .PP |
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140 | !timercmp(..., <) |
141 | !timercmp(..., >) | |
142 | !timercmp(..., !=) | |
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143 | .SH RETURN VALUE |
144 | .BR timerisset () | |
145 | and | |
146 | .BR timercmp () | |
c7094399 | 147 | return true (nonzero) or false (0). |
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148 | .SH ERRORS |
149 | No errors are defined. | |
150 | .SH CONFORMING TO | |
7aecd4d8 | 151 | Not in POSIX.1. |
d6d74fd8 | 152 | Present on most BSD derivatives. |
47297adb | 153 | .SH SEE ALSO |
d6d74fd8 | 154 | .BR gettimeofday (2), |
f0c34053 | 155 | .BR time (7) |