NAME

daytime: text, filet, gmt, local, now, string2tm, time, tm2epoch - time conversions

SYNOPSIS

include "daytime.m";
daytime := load Daytime Daytime->PATH;

Tm: adt
{
    sec:    int;    # seconds (0 to 59)
    min:    int;    # minutes (0 to 59)
    hour:   int;    # hours (0 to 23)
    mday:   int;    # day of the month (1 to 31)
    mon:    int;    # month (0 to 11)
    year:   int;    # year-1900; 2000AD is 100
    wday:   int;    # day of week (0 to 6, Sunday is 0)
    yday:   int;    # day of year (0 to 365)
    zone:   string; # time zone name
    tzoff:  int;    # time zone offset (seconds from GMT)
};

text:      fn(tm: ref Tm): string;
filet:     fn(now, t: int): string;
gmt:       fn(tim: int): ref Tm;
local:     fn(tim: int): ref Tm;
now:       fn(): int;
time:      fn(): string;
tm2epoch:  fn(tm: ref Tm): int;
string2tm: fn(date: string): ref Tm;

DESCRIPTION

These routines perform time conversions relative to the epoch 00:00:00 GMT, Jan. 1, 1970. Note the range of values for each member of the Tm adt. The conventions are the same as those of C's ctime.

Text converts a time structure referenced by tm from local or GMT time to a string in the format:

Sat Jan 1 13:00:00 GMT 2000

Filet converts the file access or modification time t from seconds since the epoch to local time as a string in the format:

Jan 1 13:00

if the file is less than 6 months old or

Jan 1 2000

if the file is older than 6 months, compared to the time now.

Gmt converts seconds since the epoch, received in tim, to a time structure in Greenwich Mean Time (GMT).

Local converts seconds since the epoch, received in tim, to a time structure in local time.

Now returns the time in seconds since the epoch, obtained by reading /dev/time (see cons(3)).

Time converts seconds since the epoch to the local time as a string in the format Fri May 19 17:01:36 BST 2000.

Tm2epoch converts a time structure referenced by tm from local or GMT time to seconds since the epoch.

String2tm returns a reference to a Tm value corresponding to the date and time in textual form in string s, which must have one of the forms below:

Sun, 06 Nov 1994 08:49:37 GMT    (RFC822, RFC1123)
Sunday, 06-Nov-94 08:49:37 GMT   (RFC850)
Sun Nov  6 08:49:37 GMT 1994     (output of text, above)

A missing time zone in any format is assumed to be GMT. String2tm returns nil if s is not correctly formed.

When local time is first requested, daytime reads a table for time zone conversion from the timezone environment variable, if that is set, and otherwise from the file /locale/timezone, which is copied from one of the other files in /locale when the system is installed. The timezone table is a text file containing lines of space-separated fields. The first line gives the normal time zone name and its difference from GMT in seconds followed by an alternative time zone name (eg, for `daylight savings' or `summer' time) and its difference from GMT followed by a newline. The remainder is a list of pairs of times (seconds past the start of 1970, in the first time zone) when the alternative time zone applies. For example:

EST -18000 EDT -14400
 9943200 25664400 41392800 57718800 ...

Greenwich Mean Time is represented by

GMT 0

SOURCE

/appl/lib/daytime.b

SEE ALSO

cons(3), sys-millisec(2)

BUGS

The sign bit of a Limbo integer holding a time will turn on 68 years from the epoch.

DAYTIME(2 )

Rev:  Tue Mar 31 02:42:39 GMT 2015