127 lines
2.7 KiB
C
127 lines
2.7 KiB
C
//---
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//
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// standard library module: time
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//
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// Provides time manipulation and representation functions.
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//
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//---
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#ifndef _TIME_H
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#define _TIME_H 1
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#include <stddef.h>
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//---
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// Some related types.
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//---
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/*
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struct tm
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Represents a point in time and gives some date information.
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*/
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struct tm
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{
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int tm_sec; // Seconds in range 0-59
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int tm_min; // Minutes in range 0-59
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int tm_hour; // Hours in range 0-23
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int tm_mday; // Day of month in range 1-31
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int tm_mon; // Month in range 0-11
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int tm_year; // Number of years since 1900
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int tm_wday; // Day of week in range 0(Sunday)-6(Saturday).
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int tm_yday; // Day of the year in range 0-365.
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int tm_isdst; // This will always be 0.
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};
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/*
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clock_t
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Only used by clock().
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*/
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typedef signed int clock_t;
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/*
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time_t
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Number of seconds elapsed since 1970-01-01 00:00:00.
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*/
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typedef signed int time_t;
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//---
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// Time access.
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//---
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/*
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clock()
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Should return elapsed CPU time since beginning of program execution.
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This is currently not implemented and returns -1.
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*/
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clock_t clock(void);
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/*
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time()
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Returns the current time as calendar time. If you need a broken-down
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time, either use the RTC API or gmtime(). However, this function is
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already based on mktime() (for hardware reasons) so it would be much
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faster to use the RTC API if possible.
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If timeptr is not NULL, it is set to the current time, that is, the
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value that is returned.
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*/
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time_t time(time_t *timeptr);
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/*
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difftime()
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Returns the number of seconds between the given points.
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*/
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double difftime(time_t end, time_t beginning);
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// But this macro should do.
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#define difftime(end, beginning) ((double)((end) - (beginning)))
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//---
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// Time representation.
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//---
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/*
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asctime()
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Converts broken-down time to string representation on the form
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"Wed Jun 30 21:49:08 1993\n". The returned string is statically
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allocated and may be overwritten by any subsequent call to a time
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function.
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*/
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char *asctime(const struct tm *time);
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/*
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ctime()
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Converts calendar time to string representation on the form
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"Wed Jun 30 21:49:08 1993\n". The returned string is statically
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allocated and may be overwritten by any subsequent call to a time
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function.
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*/
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char *ctime(const time_t *timer);
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//---
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// Time conversion.
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//---
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/*
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mktime()
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Converts broken-down time to calendar time. Computes structure fields
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tm_wday and tm_yday using the other fields. Member structures outside
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their range are normalized (e.g. 40 October becomes 9 November) and
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tm_isdst is set.
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*/
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time_t mktime(struct tm *time);
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/*
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gmtime()
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Converts calendar time to broken-down time. The returned pointer is
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statically allocated and may be overwritten by any subsequent call to
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a time function.
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*/
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struct tm *gmtime(const time_t *t);
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#endif // _TIME_H
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