1/*  Copyright (C) 1996 N.M. Maclaren
2    Copyright (C) 1996 The University of Cambridge
3
4This includes all of the code needed to handle the time.  It assumes rather
5more than is defined by POSIX, unfortunately.  Systems that do not have the
6'X/Open' extensions may need changes. */
7
8
9
10#include "header.h"
11
12#include <sys/types.h>
13#include <sys/time.h>
14
15#define TIMING
16#include "kludges.h"
17#undef TIMING
18
19
20
21#define MILLION_L    1000000l          /* For conversion to/from timeval */
22#define MILLION_D       1.0e6          /* Must be equal to MILLION_L */
23
24
25
26double current_time (double offset) {
27
28/* Get the current UTC time in seconds since the Epoch plus an offset (usually
29the time from the beginning of the century to the Epoch!) */
30
31    struct timeval current;
32
33    errno = 0;
34    if (gettimeofday(&current,NULL))
35        fatal(1,"unable to read current machine/system time",NULL);
36    return offset+current.tv_sec+1.0e-6*current.tv_usec;
37}
38
39
40
41time_t convert_time (double value, int *millisecs) {
42
43/* Convert the time to the ANSI C form. */
44
45    time_t result = (time_t)value;
46
47    if ((*millisecs = (int)(1000.0*(value-result))) >= 1000) {
48        *millisecs = 0;
49        ++result;
50    }
51    return result;
52}
53
54
55
56void adjust_time (double difference, int immediate, double ignore) {
57
58/* Adjust the current UTC time.  This is portable, even if struct timeval uses
59an unsigned long for tv_sec. */
60
61    struct timeval old, new, adjust, previous;
62    char text[40];
63    long n;
64
65/* Start by converting to timeval format. Note that we have to cater for
66negative, unsigned values. */
67
68    if ((n = (long)difference) > difference) --n;
69    adjust.tv_sec = n;
70    adjust.tv_usec = (long)(MILLION_D*(difference-n));
71    errno = 0;
72    if (gettimeofday(&old,NULL))
73        fatal(1,"unable to read machine/system time",NULL);
74    new.tv_sec = old.tv_sec+adjust.tv_sec;
75    new.tv_usec = (n = (long)old.tv_usec+(long)adjust.tv_usec);
76    if (n < 0) {
77        new.tv_usec += MILLION_L;
78        --new.tv_sec;
79    } else if (n >= MILLION_L) {
80        new.tv_usec -= MILLION_L;
81        ++new.tv_sec;
82    }
83
84/* Now diagnose the situation if necessary, and perform the dirty deed. */
85
86    if (verbose > 2)
87        fprintf(stderr,
88            "Times: old=(%ld,%.6ld) new=(%ld,%.6ld) adjust=(%ld,%.6ld)\n",
89            (long)old.tv_sec,(long)old.tv_usec,
90            (long)new.tv_sec,(long)new.tv_usec,
91            (long)adjust.tv_sec,(long)adjust.tv_usec);
92    if (immediate) {
93        errno = 0;
94        if (settimeofday(&new,NULL))
95            fatal(1,"unable to reset current system time",NULL);
96    } else {
97	previous.tv_sec  = 0;
98	previous.tv_usec = 0;
99        errno = 0;
100        if (adjtime(&adjust,&previous))
101            fatal(1,"unable to adjust current system time",NULL);
102        if (previous.tv_sec != 0 || previous.tv_usec != 0) {
103            sprintf(text,"(%ld,%.6ld)",
104                (long)previous.tv_sec,(long)previous.tv_usec);
105            if (previous.tv_sec+1.0e-6*previous.tv_usec > ignore)
106                fatal(0,"outstanding time adjustment %s",text);
107            else if (verbose)
108                fprintf(stderr,"%s: outstanding time adjustment %s\n",
109                    argv0,text);
110        }
111    }
112}
113