New (TICKS . HZ) timestamp format

This follows on a suggestion by Stefan Monnier in:
https://lists.gnu.org/r/emacs-devel/2018-08/msg00991.html
(Bug#32902).
* doc/lispref/buffers.texi (Modification Time):
* doc/lispref/os.texi (Processor Run Time, Time Calculations)
* doc/lispref/processes.texi (System Processes):
* doc/lispref/text.texi (Undo):
Let the "Time of Day" section cover timestamp format details.
* doc/lispref/os.texi (Time of Day):
Say that timestamp internal format should not be assumed.
Document new (ticks . hz) format.  Omit mention of seconds-to-time
since it is now just an alias for encode-time.
(Time Conversion): Document encode-time extension.
* etc/NEWS: Mention changes.
* lisp/calendar/cal-dst.el (calendar-system-time-basis): Now const.
* lisp/calendar/cal-dst.el (calendar-absolute-from-time)
(calendar-time-from-absolute)
(calendar-next-time-zone-transition):
* lisp/emacs-lisp/timer.el (timer-next-integral-multiple-of-time):
Simplify by using bignums, (TICKS . HZ), and new encode-time.
* lisp/emacs-lisp/timer.el (timer-next-integral-multiple-of-time):
Simplify by using bignums and new encode-time.
* lisp/calendar/parse-time.el (parse-iso8601-time-string):
Handle DST more accurately, by using new encode-time.
* lisp/calendar/time-date.el (seconds-to-time):
* lisp/calendar/timeclock.el (timeclock-seconds-to-time):
Now just an alias for encode-time.
* lisp/calendar/time-date.el (days-to-time):
* lisp/emacs-lisp/timer.el (timer--time-setter):
* lisp/net/ntlm.el (ntlm-compute-timestamp):
* lisp/obsolete/vc-arch.el (vc-arch-add-tagline):
* lisp/org/org-id.el (org-id-uuid, org-id-time-to-b36):
* lisp/tar-mode (tar-octal-time):
Don't assume timestamps default to list form.
* lisp/tar-mode.el (tar-parse-octal-long-integer):
Now an obsolete alias for tar-parse-octal-integer.
* src/keyboard.c (decode_timer): Adjust to changes to
time decoding functions elsewhere.
* src/timefns.c: Include bignum.h, limits.h.
(FASTER_TIMEFNS): New macro.
(WARN_OBSOLETE_TIMESTAMPS, CURRENT_TIME_LIST)
(timespec_hz, trillion, ztrillion):
New constants.
(make_timeval): Use TIME_T_MAX instead of its definiens.
(check_time_validity, time_add, time_subtract):
Remove.  All uses removed.
(disassemble_lisp_time): Remove; old code now folded into
decode_lisp_time.  All callers changed.
(invalid_hz, s_ns_to_double, ticks_hz_list4, mpz_set_time)
(timespec_mpz, timespec_ticks, time_hz_ticks)
(lisp_time_hz_ticks, lisp_time_seconds)
(time_form_stamp, lisp_time_form_stamp, decode_ticks_hz)
(decode_lisp_time, mpz_time, list4_to_timespec):
New functions.
(decode_float_time, decode_time_components, lisp_to_timespec):
Adjust to new struct lisp_time, which does not lose
information like the old one did.
(enum timeform): New enum.
(decode_time_components): New arg FORM.  All callers changed.
RESULT and DRESULT are now mutually exclusive; no callers need
to change because of this.
(decode_time_components, lisp_time_struct)
(lisp_seconds_argument, time_arith, make_lisp_time, Ffloat_time)
(Fencode_time):
Add support for (TICKS . HZ) form.
(DECODE_SECS_ONLY): New constant.
(lisp_time_struct): 2nd arg is now enum timeform, not int.
All callers changed.
(check_tm_member): Support bignums.m
(Fencode_time): Add new two-arg functionality.
* src/systime.h (struct lisp_time): Now ticks+hz rather than
hi+lo+us+ps, since ticks+hz does not lose info.
* test/src/systime-tests.el (time-equal-p-nil-nil):
New test.

1 files changed, 13 insertions, 29 deletions

diff --git a/lisp/emacs-lisp/timer.el b/lisp/emacs-lisp/timer.el
index 74d37b0eaed..927e640feaa 100644
--- a/lisp/emacs-lisp/timer.el
+++ b/lisp/emacs-lisp/timer.el
@@ -57,17 +57,11 @@
 
 (defun timer--time-setter (timer time)
   (timer--check timer)
-  (setf (timer--high-seconds timer) (pop time))
-  (let ((low time) (usecs 0) (psecs 0))
-    (when (consp time)
-      (setq low (pop time))
-      (when time
-        (setq usecs (pop time))
-        (when time
-          (setq psecs (car time)))))
-    (setf (timer--low-seconds timer) low)
-    (setf (timer--usecs timer) usecs)
-    (setf (timer--psecs timer) psecs)
+  (let ((lt (encode-time time 'list)))
+    (setf (timer--high-seconds timer) (nth 0 lt))
+    (setf (timer--low-seconds timer) (nth 1 lt))
+    (setf (timer--usecs timer) (nth 2 lt))
+    (setf (timer--psecs timer) (nth 3 lt))
     time))
 
 ;; Pseudo field `time'.
@@ -102,24 +96,14 @@ fire each time Emacs is idle for that many seconds."
   "Yield the next value after TIME that is an integral multiple of SECS.
 More precisely, the next value, after TIME, that is an integral multiple
 of SECS seconds since the epoch.  SECS may be a fraction."
-  (let* ((trillion 1000000000000)
-	 (time-sec (+ (nth 1 time)
-		      (* 65536 (nth 0 time))))
-	 (delta-sec (mod (- time-sec) secs))
-	 (next-sec (+ time-sec (floor delta-sec)))
-	 (next-sec-psec (floor (* trillion (mod delta-sec 1))))
-	 (sub-time-psec (+ (or (nth 3 time) 0)
-			   (* 1000000 (nth 2 time))))
-	 (psec-diff (- sub-time-psec next-sec-psec)))
-    (if (and (<= next-sec time-sec) (< 0 psec-diff))
-	(setq next-sec-psec (+ sub-time-psec
-			       (mod (- psec-diff) (* trillion secs)))))
-    (setq next-sec (+ next-sec (floor next-sec-psec trillion)))
-    (setq next-sec-psec (mod next-sec-psec trillion))
-    (list (floor next-sec 65536)
-	  (floor (mod next-sec 65536))
-	  (floor next-sec-psec 1000000)
-	  (floor (mod next-sec-psec 1000000)))))
+  (let* ((ticks-hz (if (and (consp time) (integerp (car time))
+			    (integerp (cdr time)) (< 0 (cdr time)))
+		       time
+		     (encode-time time 1000000000000)))
+	 (hz (cdr ticks-hz))
+	 (s-ticks (* secs hz))
+	 (more-ticks (+ (car ticks-hz) s-ticks)))
+    (encode-time (cons (- more-ticks (% more-ticks s-ticks)) hz))))
 
 (defun timer-relative-time (time secs &optional usecs psecs)
   "Advance TIME by SECS seconds and optionally USECS microseconds