X-Git-Url: http://git.chise.org/gitweb/?a=blobdiff_plain;ds=sidebyside;f=lisp%2Ftime-date.el;h=e9babceb019fa5222d0803e11ead683e12abd906;hb=4a9268a5cbbcc7c74fc6fa94d7a3409cda1d6dbf;hp=3ec6d96f9126469704d273ac017685e6df30949f;hpb=3a75505b36e914f05480b86020edd727c6abe2fb;p=elisp%2Fgnus.git-

diff --git a/lisp/time-date.el b/lisp/time-date.el
index 3ec6d96..e9babce 100644
--- a/lisp/time-date.el
+++ b/lisp/time-date.el
@@ -32,7 +32,7 @@
 
 ;;;###autoload
 (defun date-to-time (date)
-  "Convert DATE into time."
+  "Parse a string that represents a date-time and return a time value."
   (condition-case ()
       (apply 'encode-time
 	     (parse-time-string
@@ -46,25 +46,29 @@
     (error (error "Invalid date: %s" date))))
 
 (defun time-to-seconds (time)
-  "Convert TIME to a floating point number."
+  "Convert time value TIME to a floating point number.
+You can use `float-time' instead."
   (+ (* (car time) 65536.0)
      (cadr time)
      (/ (or (nth 2 time) 0) 1000000.0)))
 
+;;;###autoload
 (defun seconds-to-time (seconds)
-  "Convert SECONDS (a floating point number) to an Emacs time structure."
+  "Convert SECONDS (a floating point number) to a time value."
   (list (floor seconds 65536)
 	(floor (mod seconds 65536))
 	(floor (* (- seconds (ffloor seconds)) 1000000))))
 
+;;;###autoload
 (defun time-less-p (t1 t2)
-  "Say whether time T1 is less than time T2."
+  "Say whether time value T1 is less than time value T2."
   (or (< (car t1) (car t2))
       (and (= (car t1) (car t2))
 	   (< (nth 1 t1) (nth 1 t2)))))
 
+;;;###autoload
 (defun days-to-time (days)
-  "Convert DAYS into time."
+  "Convert DAYS into a time value."
   (let* ((seconds (* 1.0 days 60 60 24))
 	 (rest (expt 2 16))
 	 (ms (condition-case nil (floor (/ seconds rest))
@@ -72,8 +76,10 @@
     (list ms (condition-case nil (round (- seconds (* ms rest)))
 	       (range-error (expt 2 16))))))
 
+;;;###autoload
 (defun time-since (time)
-  "Return the time since TIME, which is either an internal time or a date."
+  "Return the time elapsed since TIME.
+TIME should be either a time value or a date-time string."
   (when (stringp time)
     ;; Convert date strings to internal time.
     (setq time (date-to-time time)))
@@ -83,26 +89,65 @@
     (list (- (+ (car current) (if rest -1 0)) (car time))
 	  (- (+ (or rest 0) (nth 1 current)) (nth 1 time)))))
 
-(defun subtract-time (t1 t2)
-  "Subtract two internal times."
+;;;###autoload
+(defalias 'subtract-time 'time-subtract)
+
+;;;###autoload
+(defun time-subtract (t1 t2)
+  "Subtract two time values.
+Return the difference in the format of a time value."
   (let ((borrow (< (cadr t1) (cadr t2))))
     (list (- (car t1) (car t2) (if borrow 1 0))
 	  (- (+ (if borrow 65536 0) (cadr t1)) (cadr t2)))))
 
+;;;###autoload
+(defun time-add (t1 t2)
+  "Add two time values.  One should represent a time difference."
+  (let ((high (car t1))
+	(low (if (consp (cdr t1)) (nth 1 t1) (cdr t1)))
+	(micro (if (numberp (car-safe (cdr-safe (cdr t1))))
+		   (nth 2 t1)
+		 0))
+	(high2 (car t2))
+	(low2 (if (consp (cdr t2)) (nth 1 t2) (cdr t2)))
+	(micro2 (if (numberp (car-safe (cdr-safe (cdr t2))))
+		    (nth 2 t2)
+		  0)))
+    ;; Add
+    (setq micro (+ micro micro2))
+    (setq low (+ low low2))
+    (setq high (+ high high2))
+
+    ;; Normalize
+    ;; `/' rounds towards zero while `mod' returns a positive number,
+    ;; so we can't rely on (= a (+ (* 100 (/ a 100)) (mod a 100))).
+    (setq low (+ low (/ micro 1000000) (if (< micro 0) -1 0)))
+    (setq micro (mod micro 1000000))
+    (setq high (+ high (/ low 65536) (if (< low 0) -1 0)))
+    (setq low (logand low 65535))
+
+    (list high low micro)))
+
+;;;###autoload
 (defun date-to-day (date)
-  "Return the number of days between year 1 and DATE."
+  "Return the number of days between year 1 and DATE.
+DATE should be a date-time string."
   (time-to-days (date-to-time date)))
 
+;;;###autoload
 (defun days-between (date1 date2)
-  "Return the number of days between DATE1 and DATE2."
+  "Return the number of days between DATE1 and DATE2.
+DATE1 and DATE2 should be date-time strings."
   (- (date-to-day date1) (date-to-day date2)))
 
+;;;###autoload
 (defun date-leap-year-p (year)
   "Return t if YEAR is a leap year."
   (or (and (zerop (% year 4))
 	   (not (zerop (% year 100))))
       (zerop (% year 400))))
 
+;;;###autoload
 (defun time-to-day-in-year (time)
   "Return the day number within the year of the date month/day/year."
   (let* ((tim (decode-time time))
@@ -116,14 +161,16 @@
 	(setq day-of-year (1+ day-of-year))))
     day-of-year))
 
+;;;###autoload
 (defun time-to-days (time)
   "The number of days between the Gregorian date 0001-12-31bce and TIME.
+TIME should be a time value.
 The Gregorian date Sunday, December 31, 1bce is imaginary."
   (let* ((tim (decode-time time))
 	 (month (nth 4 tim))
 	 (day (nth 3 tim))
 	 (year (nth 5 tim)))
-    (+ (time-to-day-in-year time)	; 	Days this year
+    (+ (time-to-day-in-year time)	;	Days this year
        (* 365 (1- year))		;	+ Days in prior years
        (/ (1- year) 4)			;	+ Julian leap years
        (- (/ (1- year) 100))		;	- century years
@@ -136,8 +183,8 @@ The number of days will be returned as a floating point number."
 
 ;;;###autoload
 (defun safe-date-to-time (date)
-  "Parse DATE and return a time structure.
-If DATE is malformed, a zero time will be returned."
+  "Parse a string that represents a date-time and return a time value.
+If DATE is malformed, return a time value of zeros."
   (condition-case ()
       (date-to-time date)
     (error '(0 0))))