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sourceware.org Git - glibc.git/blob - sysdeps/unix/clock_gettime.c
1 /* clock_gettime -- Get the current time from a POSIX clockid_t. Unix version.
2 Copyright (C) 1999,2000,2001,2002,2003,2004 Free Software Foundation, Inc.
3 This file is part of the GNU C Library.
5 The GNU C Library is free software; you can redistribute it and/or
6 modify it under the terms of the GNU Lesser General Public
7 License as published by the Free Software Foundation; either
8 version 2.1 of the License, or (at your option) any later version.
10 The GNU C Library is distributed in the hope that it will be useful,
11 but WITHOUT ANY WARRANTY; without even the implied warranty of
12 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
13 Lesser General Public License for more details.
15 You should have received a copy of the GNU Lesser General Public
16 License along with the GNU C Library; if not, write to the Free
17 Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
24 #include <libc-internal.h>
29 /* Clock frequency of the processor. We make it a 64-bit variable
30 because some jokers are already playing with processors with more
32 static hp_timing_t freq
;
35 /* This function is defined in the thread library. */
36 extern int __pthread_clock_gettime (clockid_t clock_id
, hp_timing_t freq
,
38 __attribute__ ((__weak__
));
41 hp_timing_gettime (clockid_t clock_id
, struct timespec
*tp
)
45 if (__builtin_expect (freq
== 0, 0))
47 /* This can only happen if we haven't initialized the `freq'
48 variable yet. Do this now. We don't have to protect this
49 code against multiple execution since all of them should
50 lead to the same result. */
51 freq
= __get_clockfreq ();
52 if (__builtin_expect (freq
== 0, 0))
53 /* Something went wrong. */
57 if (clock_id
!= CLOCK_PROCESS_CPUTIME_ID
58 && __pthread_clock_gettime
!= NULL
)
59 return __pthread_clock_gettime (clock_id
, freq
, tp
);
61 /* Get the current counter. */
64 /* Compute the offset since the start time of the process. */
65 tsc
-= GL(dl_cpuclock_offset
);
67 /* Compute the seconds. */
68 tp
->tv_sec
= tsc
/ freq
;
70 /* And the nanoseconds. This computation should be stable until
71 we get machines with about 16GHz frequency. */
72 tp
->tv_nsec
= ((tsc
% freq
) * UINT64_C (1000000000)) / freq
;
80 realtime_gettime (struct timespec
*tp
)
83 int retval
= gettimeofday (&tv
, NULL
);
85 /* Convert into `timespec'. */
86 TIMEVAL_TO_TIMESPEC (&tv
, tp
);
91 /* Get current value of CLOCK and store it in TP. */
93 clock_gettime (clockid_t clock_id
, struct timespec
*tp
)
103 #ifndef HANDLED_REALTIME
110 #ifdef SYSDEP_GETTIME_CPU
114 if ((clock_id
& ((1 << CLOCK_IDFIELD_SIZE
) - 1))
115 == CLOCK_THREAD_CPUTIME_ID
)
116 retval
= hp_timing_gettime (clock_id
, tp
);
119 __set_errno (EINVAL
);
122 #if HP_TIMING_AVAIL && !defined HANDLED_CPUTIME
123 case CLOCK_PROCESS_CPUTIME_ID
:
124 retval
= hp_timing_gettime (clock_id
, tp
);
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