1 /* coap_time.c -- Clock Handling
2 *
3 * Copyright (C) 2015 Olaf Bergmann <bergmann@tzi.org>
4 *
5 * This file is part of the CoAP library libcoap. Please see
6 * README for terms of use.
7 */
8
9 #ifdef WITH_POSIX
10 #include <time.h>
11 #include <sys/time.h>
12 #include <unistd.h> /* _POSIX_TIMERS */
13
14 #include "coap_config.h"
15 #include "coap_time.h"
16
17 static coap_time_t coap_clock_offset = 0;
18
19 #if _POSIX_TIMERS && !defined(__APPLE__)
20 /* _POSIX_TIMERS is > 0 when clock_gettime() is available */
21
22 /* Use real-time clock for correct timestamps in coap_log(). */
23 #define COAP_CLOCK CLOCK_REALTIME
24 #endif
25
26 void
coap_clock_init(void)27 coap_clock_init(void) {
28 #ifdef COAP_CLOCK
29 struct timespec tv;
30 clock_gettime(COAP_CLOCK, &tv);
31 #else /* _POSIX_TIMERS */
32 struct timeval tv;
33 gettimeofday(&tv, NULL);
34 #endif /* not _POSIX_TIMERS */
35
36 coap_clock_offset = tv.tv_sec;
37 }
38
39 /* creates a Qx.frac from fval */
40 #define Q(frac,fval) ((coap_tick_t)(((1 << (frac)) * (fval))))
41
42 /* number of frac bits for sub-seconds */
43 #define FRAC 10
44
45 /* rounds val up and right shifts by frac positions */
46 #define SHR_FP(val,frac) (((val) + (1 << ((frac) - 1))) >> (frac))
47
48 void
coap_ticks(coap_tick_t * t)49 coap_ticks(coap_tick_t *t) {
50 unsigned long tmp;
51
52 #ifdef COAP_CLOCK
53 struct timespec tv;
54 clock_gettime(COAP_CLOCK, &tv);
55 /* Possible errors are (see clock_gettime(2)):
56 * EFAULT tp points outside the accessible address space.
57 * EINVAL The clk_id specified is not supported on this system.
58 * Both cases should not be possible here.
59 */
60
61 tmp = SHR_FP(tv.tv_nsec * Q(FRAC, (COAP_TICKS_PER_SECOND/1000000000.0)), FRAC);
62 #else /* _POSIX_TIMERS */
63 /* Fall back to gettimeofday() */
64
65 struct timeval tv;
66 gettimeofday(&tv, NULL);
67 /* Possible errors are (see gettimeofday(2)):
68 * EFAULT One of tv or tz pointed outside the accessible address space.
69 * EINVAL Timezone (or something else) is invalid.
70 * Both cases should not be possible here.
71 */
72
73 tmp = SHR_FP(tv.tv_usec * Q(FRAC, (COAP_TICKS_PER_SECOND/1000000.0)), FRAC);
74 #endif /* not _POSIX_TIMERS */
75
76 /* Finally, convert temporary FP representation to multiple of
77 * COAP_TICKS_PER_SECOND */
78 *t = tmp + (tv.tv_sec - coap_clock_offset) * COAP_TICKS_PER_SECOND;
79 }
80
81 coap_time_t
coap_ticks_to_rt(coap_tick_t t)82 coap_ticks_to_rt(coap_tick_t t) {
83 return coap_clock_offset + (t / COAP_TICKS_PER_SECOND);
84 }
85
86 #undef Q
87 #undef FRAC
88 #undef SHR_FP
89
90 #else /* WITH_POSIX */
91
92 /* make compilers happy that do not like empty modules */
dummy()93 static inline void dummy()
94 {
95 }
96
97 #endif /* not WITH_POSIX */
98
99
