1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
|
/*
* timetoa.h -- time_t related string formatting
*
* Written by Juergen Perlinger (perlinger@ntp.org) for the NTP project.
* The contents of 'html/copyright.html' apply.
*
* Printing a 'time_t' has some portability pitfalls, due to it's opaque
* base type. The only requirement imposed by the standard is that it
* must be a numeric type. For all practical purposes it's a signed int,
* and 32 bits are common.
*
* Since the UN*X time epoch will cause a signed integer overflow for
* 32-bit signed int values in the year 2038, implementations slowly
* move to 64bit base types for time_t, even in 32-bit environments. In
* such an environment sizeof(time_t) could be bigger than sizeof(long)
* and the commonly used idiom of casting to long leads to truncation.
*
* As the printf() family has no standardised type specifier for time_t,
* guessing the right output format specifier is a bit troublesome and
* best done with the help of the preprocessor and "config.h".
*/
#ifndef TIMETOA_H
#define TIMETOA_H
#include "ntp_fp.h"
#include "ntp_stdlib.h"
#include "ntp_unixtime.h"
/*
* Given the size of time_t, guess what can be used as an unsigned value
* to hold a time_t and the printf() format specifcation.
*
* These should be used with the string constant concatenation feature
* of the compiler like this:
*
* printf("a time stamp: %" TIME_FORMAT " and more\n", a_time_t_value);
*
* It's not exactly nice, but there's not much leeway once we want to
* use the printf() family on time_t values.
*/
#if SIZEOF_TIME_T <= SIZEOF_INT
typedef unsigned int u_time;
#define TIME_FORMAT "d"
#define UTIME_FORMAT "u"
#elif SIZEOF_TIME_T <= SIZEOF_LONG
typedef unsigned long u_time;
#define TIME_FORMAT "ld"
#define UTIME_FORMAT "lu"
#elif defined(SIZEOF_LONG_LONG) && SIZEOF_TIME_T <= SIZEOF_LONG_LONG
typedef unsigned long long u_time;
#define TIME_FORMAT "lld"
#define UTIME_FORMAT "llu"
#else
#include "GRONK: what size has a time_t here?"
#endif
/*
* general fractional time stamp formatting.
*
* secs - integral seconds of time stamp
* frac - fractional units
* prec - log10 of units per second (3=milliseconds, 6=microseconds,..)
* or in other words: the count of decimal digits required.
* If prec is < 0, abs(prec) is taken for the precision and secs
* is treated as an unsigned value.
*
* The function will eventually normalise the fraction and adjust the
* seconds accordingly.
*
* This function uses the string buffer library for the return value,
* so do not keep the resulting pointers around.
*/
extern const char *
format_time_fraction(time_t secs, long frac, int prec);
#endif /* !defined(TIMETOA_H) */
|
