scsh-0.6/scsh/time.scm

270 lines
9.6 KiB
Scheme

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