268 lines
9.4 KiB
Scheme
268 lines
9.4 KiB
Scheme
;;; Time interface for scsh.
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;;; Copyright (c) 1994 by Olin Shivers.
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;;; Should I have a (FILL-IN-DATE! date) procedure that fills in
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;;; the redundant info in a date record?
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;;; - month-day & month defined -> week-day & year-day filled in.
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;;; - month-day and year-day filled in from week-day and year-day
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;;; (not provided by mktime(), but can be synthesized)
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;;; - If tz-secs and tz-name not defined, filled in from current time zone.
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;;; - If tz-name not defined, fabbed from tz-secs.
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;;; - If tz-secs not defined, filled in from tz-name.
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;;; A TIME is an instant in the history of the universe; it is location
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;;; independent, barring relativistic effects. It is measured as the
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;;; number of seconds elapsed since "epoch" -- January 1, 1970 UTC.
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;;; A DATE is a *local* name for an instant in time -- which instant
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;;; it names depends on your time zone (February 23, 1994 4:37 pm happens
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;;; at different moments in Boston and Hong Kong).
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;;; DATE definition
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;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
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;;; We hack this so the date maker can take take the last three slots
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;;; as optional arguments.
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(define-record %date ; A Posix tm struct
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seconds ; Seconds after the minute (0-59)
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minute ; Minutes after the hour (0-59)
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hour ; Hours since midnight (0-23)
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month-day ; Day of the month (1-31)
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month ; Months since January (0-11)
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year ; Years since 1900
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tz-name ; Time zone as a string.
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tz-secs ; Time zone as an integer: seconds west of UTC.
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summer? ; Summer time (Daylight savings) in effect?
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week-day ; Days since Sunday (0-6) ; Redundant
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year-day) ; Days since Jan. 1 (0-365) ; Redundant
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(define date? %date?)
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(define date:seconds %date:seconds)
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(define date:minute %date:minute)
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(define date:hour %date:hour)
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(define date:month-day %date:month-day)
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(define date:month %date:month)
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(define date:year %date:year)
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(define date:tz-name %date:tz-name)
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(define date:tz-secs %date:tz-secs)
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(define date:summer? %date:summer?)
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(define date:week-day %date:week-day)
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(define date:year-day %date:year-day)
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(define set-date:seconds set-%date:seconds)
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(define set-date:minute set-%date:minute)
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(define set-date:hour set-%date:hour)
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(define set-date:month-day set-%date:month-day)
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(define set-date:month set-%date:month)
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(define set-date:year set-%date:year)
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(define set-date:tz-name set-%date:tz-name)
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(define set-date:tz-secs set-%date:tz-secs)
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(define set-date:summer? set-%date:summer?)
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(define set-date:week-day set-%date:week-day)
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(define set-date:year-day set-%date:year-day)
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(define modify-date:seconds modify-%date:seconds)
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(define modify-date:minute modify-%date:minute)
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(define modify-date:hour modify-%date:hour)
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(define modify-date:month-day modify-%date:month-day)
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(define modify-date:month modify-%date:month)
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(define modify-date:year modify-%date:year)
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(define modify-date:tz-name modify-%date:tz-name)
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(define modify-date:tz-secs modify-%date:tz-secs)
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(define modify-date:summer? modify-%date:summer?)
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(define modify-date:week-day modify-%date:week-day)
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(define modify-date:year-day modify-%date:year-day)
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(define (make-date s mi h md mo y . args)
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(let-optionals args ((tzn #f) (tzs #f) (s? #f) (wd 0) (yd 0))
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(make-%date s mi h md mo y tzn tzs s? wd yd)))
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;;; Not exported to interface.
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(define (time-zone? x)
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(or (integer? x) ; Seconds offset from UTC.
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(string? x) ; Time zone name, e.g. "EDT"
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(not x))) ; Local time
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;;; Time
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;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
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; TICKS/SEC is defined in OS-dependent code.
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; C fun is OS-dependent
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; TODO: all C files are identical, so move it to time1.c
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; returns (list secs ticks)
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(import-os-error-syscall %time+ticks () "time_plus_ticks")
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(define (time+ticks)
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(apply values (%time+ticks)))
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(define (time+ticks->time secs ticks)
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(+ secs (/ ticks (ticks/sec))))
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(import-os-error-syscall %time () "scheme_time")
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(import-os-error-syscall %date->time
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(sec min hour month-day month year
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tz-name ; #f or string
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tz-secs ; #f or int
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summer?) "date2time")
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(define (time . args) ; optional arg [date]
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(if (pair? args)
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(if (null? (cdr args))
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(let ((date (check-arg date? (car args) time)))
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(let ((err?.time
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(%date->time (date:seconds date)
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(date:minute date)
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(date:hour date)
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(date:month-day date)
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(date:month date)
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(date:year date)
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(date:tz-name date) ; #f or string
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(date:tz-secs date) ; #f or int
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(date:summer? date))))
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(if (car err?.time)
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(error "Error converting date to time." args)
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(cdr err?.time))))
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(error "Too many arguments to TIME procedure" args))
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(%time))) ; Fast path for (time).
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;;; Date
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;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
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(import-os-error-syscall %time->date (time zone) "time2date")
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(define (date . args) ; Optional args [time zone]
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(let ((time (if (pair? args)
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(real->exact-integer (check-arg real? (car args) date))
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(time)))
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(zone (check-arg time-zone?
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(and (pair? args) (:optional (cdr args) #f))
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date)))
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(apply
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(lambda (seconds minute hour month-day month
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year tz-name tz-secs summer? week-day year-day)
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(make-%date seconds minute hour month-day month
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year
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(format-time-zone (or tz-name "UTC") tz-secs)
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tz-secs summer? week-day year-day))
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(%time->date time zone))))
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;;; Formatting date strings
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;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
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(define (date->string date) ; Sun Sep 16 01:03:52 1973
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(format-date "~a ~b ~d ~H:~M:~S ~Y" date))
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(define (format-date fmt date)
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(check-arg date? date format-date)
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(let ((result
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(%format-date fmt
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(date:seconds date)
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(date:minute date)
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(date:hour date)
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(date:month-day date)
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(date:month date)
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(date:year date)
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(if (string? (date:tz-name date))
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(date:tz-name date)
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(deintegerize-time-zone (date:tz-secs date)))
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(date:summer? date)
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(date:week-day date)
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(date:year-day date))))
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(cond ((not result) (error "~ without argument in format-date" fmt))
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(else result))))
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(import-os-error-syscall %format-date
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(fmt seconds minute hour month-day month year tz-name summer? week-day
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year-day)
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"format_date")
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;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
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;;; Obsoleted, since DATE records now include time zone info.
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;;; If you want the UTC offset, just do (date:tz-secs (date [time tz])).
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;;;
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;(define (utc-offset . args) ; Optional args [time tz]
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; (let ((tim (if (pair? args)
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; (real->exact-integer (check-arg real? (car args) utc-offset))
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; (time)))
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; (tz (and (pair? args)
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; (check-arg time-zone? (:optional (cdr args) #f) utc-offset))))
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; (if (integer? tz) tz
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; (- (time (date tim tz) 0) tim))))
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;(define (time-zone . args) ; Optional args [summer? tz]
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; (let ((tz (and (pair? args)
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; (check-arg time-zone? (:optional (cdr args) #f) time-zone))))
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; (if (integer? tz)
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; (deintegerize-time-zone tz)
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; (let* ((summer? (if (pair? args) (car args) (time)))
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; (summer? (if (real? summer?) (real->exact-integer summer?) summer?)))
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; (receive (err zone) (%time-zone/errno summer? tz)
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; (if err (errno-error err time-zone summer? tz)
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; zone))))))
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;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
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(define (compose-8/24 hi-8 lo-24)
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(let ((val (+ (arithmetic-shift hi-8 24) lo-24)))
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(if (zero? (bitwise-and hi-8 #x80)) val
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;; Oops -- it's a negative 32-bit value.
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;; Or in all the sign bits.
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(bitwise-ior (bitwise-not #xffffffff)
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val))))
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;;; Render a number as a two-digit base ten numeral.
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;;; Pathetic. FORMAT should do this for me.
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(define (two-digits n)
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(let ((s (number->string n)))
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(if (= (string-length s) 1)
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(string-append "0" s)
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s)))
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;;; If time-zone is an integer, convert to a Posix-format string of the form:
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;;; UTC+hh:mm:ss
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(define (deintegerize-time-zone tz)
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(if (integer? tz)
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(format-time-zone "UTC" tz)
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tz))
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;;; NAME is a simple time-zone name such as "EST" or "UTC". You get them
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;;; back from the Unix time functions as the values of the char *tzname[2]
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;;; standard/dst vector. The problem is that these time are ambiguous.
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;;; This function makes them unambiguous by tacking on the UTC offset
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;;; in Posix format, such as "EST+5". You need to do this for two reasons:
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;;; 1. Simple time-zone strings are not recognised at all sites.
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;;; For example, HP-UX doesn't understand "EST", but does understand "EST+5"
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;;; 2. Time zones represented as UTC offsets (e.g., "UTC+5") are returned
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;;; back from the Unix time software as just "UTC", which in the example
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;;; just given is 5 hours off. Try setting TZ=UTC+5 and running the date(1)
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;;; program. It will give you EST time, but print the time zone as "UTC".
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;;; Oops.
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(define (format-time-zone name offset)
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(if (zero? offset) name
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(receive (sign offset)
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(if (< offset 0)
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(values #\+ (- offset)) ; Notice the flipped sign
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(values #\- offset)) ; of SIGN.
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(let* ((offset (modulo offset 86400)) ; seconds/day
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(h (quotient offset 3600)) ; seconds/hour
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(m (quotient (modulo offset 3600) 60))
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(s (modulo offset 60)))
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(if (zero? s)
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(if (zero? m)
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(format #f "~a~a~d" name sign h) ; name+h
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(format #f "~a~a~a:~a" ; name+hh:mm
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name sign (two-digits h) (two-digits m)))
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(format #f "~a~a~a:~a:~a" ; name+hh:mm:ss
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name sign
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(two-digits h) (two-digits m) (two-digits s)))))))
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