1 ------------------------------------------------------------------------------
3 -- GNAT RUN-TIME COMPONENTS --
5 -- A D A . C A L E N D A R --
9 -- Copyright (C) 1992-2024, Free Software Foundation, Inc. --
11 -- This specification is derived from the Ada Reference Manual for use with --
12 -- GNAT. The copyright notice above, and the license provisions that follow --
13 -- apply solely to the contents of the part following the private keyword. --
15 -- GNAT is free software; you can redistribute it and/or modify it under --
16 -- terms of the GNU General Public License as published by the Free Soft- --
17 -- ware Foundation; either version 3, or (at your option) any later ver- --
18 -- sion. GNAT is distributed in the hope that it will be useful, but WITH- --
19 -- OUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY --
20 -- or FITNESS FOR A PARTICULAR PURPOSE. --
22 -- As a special exception under Section 7 of GPL version 3, you are granted --
23 -- additional permissions described in the GCC Runtime Library Exception, --
24 -- version 3.1, as published by the Free Software Foundation. --
26 -- You should have received a copy of the GNU General Public License and --
27 -- a copy of the GCC Runtime Library Exception along with this program; --
28 -- see the files COPYING3 and COPYING.RUNTIME respectively. If not, see --
29 -- <http://www.gnu.org/licenses/>. --
31 -- GNAT was originally developed by the GNAT team at New York University. --
32 -- Extensive contributions were provided by Ada Core Technologies Inc. --
34 ------------------------------------------------------------------------------
36 package Ada
.Calendar
with
38 Abstract_State
=> (Clock_Time
with Synchronous
),
39 Initializes
=> Clock_Time
44 -- Declarations representing limits of allowed local time values. Note that
45 -- these do NOT constrain the possible stored values of time which may well
46 -- permit a larger range of times (this is explicitly allowed in Ada 95).
48 subtype Year_Number
is Integer range 1901 .. 2399;
49 subtype Month_Number
is Integer range 1 .. 12;
50 subtype Day_Number
is Integer range 1 .. 31;
52 -- A Day_Duration value of 86_400.0 designates a new day
54 subtype Day_Duration
is Duration range 0.0 .. 86_400
.0
;
56 function Clock
return Time
with
59 -- The returned time value is the number of nanoseconds since the start
60 -- of Ada time (1901-01-01 00:00:00.0 UTC). If leap seconds are enabled,
61 -- the result will contain all elapsed leap seconds since the start of
62 -- Ada time until now.
64 function Year
(Date
: Time
) return Year_Number
;
65 function Month
(Date
: Time
) return Month_Number
;
66 function Day
(Date
: Time
) return Day_Number
;
67 function Seconds
(Date
: Time
) return Day_Duration
;
68 -- SPARK Note: These routines, just like Split and Time_Of below, might use
69 -- the OS-specific timezone database that is typically stored in a file.
70 -- This side effect needs to be modeled, so there is no Global => null.
74 Year
: out Year_Number
;
75 Month
: out Month_Number
;
77 Seconds
: out Day_Duration
);
78 -- Break down a time value into its date components set in the current
79 -- time zone. If Split is called on a time value created using Ada 2005
80 -- Time_Of in some arbitrary time zone, the input value will always be
81 -- interpreted as relative to the local time zone.
87 Seconds
: Day_Duration
:= 0.0) return Time
;
88 -- GNAT Note: Normally when procedure Split is called on a Time value
89 -- result of a call to function Time_Of, the out parameters of procedure
90 -- Split are identical to the in parameters of function Time_Of. However,
91 -- when a non-existent time of day is specified, the values for Seconds
92 -- may or may not be different. This may happen when Daylight Saving Time
93 -- (DST) is in effect, on the day when switching to DST, if Seconds
94 -- specifies a time of day in the hour that does not exist. For example,
97 -- Time_Of (Year => 1998, Month => 4, Day => 5, Seconds => 10740.0)
99 -- will return a Time value T. If Split is called on T, the resulting
100 -- Seconds may be 14340.0 (3:59:00) instead of 10740.0 (2:59:00 being
101 -- a time that not exist).
103 function "+" (Left
: Time
; Right
: Duration) return Time
106 function "+" (Left
: Duration; Right
: Time
) return Time
109 function "-" (Left
: Time
; Right
: Duration) return Time
112 function "-" (Left
: Time
; Right
: Time
) return Duration
115 -- The first three functions will raise Time_Error if the resulting time
116 -- value is less than the start of Ada time in UTC or greater than the
117 -- end of Ada time in UTC. The last function will raise Time_Error if the
118 -- resulting difference cannot fit into a duration value.
120 function "<" (Left
, Right
: Time
) return Boolean with Global
=> null;
121 function "<=" (Left
, Right
: Time
) return Boolean with Global
=> null;
122 function ">" (Left
, Right
: Time
) return Boolean with Global
=> null;
123 function ">=" (Left
, Right
: Time
) return Boolean with Global
=> null;
125 Time_Error
: exception;
128 -- Mark the private part as SPARK_Mode Off to avoid accounting for variable
129 -- Invalid_Time_Zone_Offset in abstract state.
131 pragma SPARK_Mode
(Off
);
133 pragma Inline
(Clock
);
135 pragma Inline
(Year
);
136 pragma Inline
(Month
);
143 pragma Inline
("<=");
145 pragma Inline
(">=");
147 -- The units used in this version of Ada.Calendar are nanoseconds. The
148 -- following constants provide values used in conversions of seconds or
149 -- days to the underlying units.
151 Nano
: constant := 1_000_000_000
;
152 Nano_F
: constant := 1_000_000_000
.0
;
153 Nanos_In_Day
: constant := 86_400_000_000_000
;
154 Secs_In_Day
: constant := 86_400
;
156 ----------------------------
157 -- Implementation of Time --
158 ----------------------------
160 -- Time is represented as a signed 64 bit signed integer count of
161 -- nanoseconds since the "epoch" 2150-01-01 00:00:00 UTC. Thus a value of 0
162 -- represents the epoch. As of this writing, the epoch is in the future,
163 -- so Time values returned by Clock will be negative.
165 -- Time values produced by Time_Of are internally normalized to UTC
166 -- regardless of their local time zone. This representation ensures correct
167 -- handling of leap seconds as well as performing arithmetic. In Ada 95,
168 -- Split and Time_Of will treat a time value as being in the local time
169 -- zone, in Ada 2005, Split and Time_Of will treat a time value as being in
170 -- the designated time zone by the formal parameter or in UTC by
171 -- default. The size of the type is large enough to cover the Ada
172 -- range of time (1901-01-01T00:00:00.0 UTC - 2399-12-31T23:59:59.999999999
179 -- Due to Earth's slowdown, the astronomical time is not as precise as the
180 -- International Atomic Time. To compensate for this inaccuracy, a single
181 -- leap second is added after the last day of June or December. The count
182 -- of seconds during those occurrences becomes:
184 -- ... 58, 59, leap second 60, 0, 1, 2 ...
186 -- Unlike leap days, leap seconds occur simultaneously around the world.
187 -- In other words, if a leap second occurs at 23:59:60 UTC, it also occurs
188 -- on 18:59:60 -5 the same day or 2:59:60 +2 on the next day.
190 -- Leap seconds do not follow a formula. The International Earth Rotation
191 -- and Reference System Service decides when to add one. Leap seconds are
192 -- included in the representation of time in Ada 95 mode. As a result,
193 -- the following two time values will differ by two seconds:
195 -- 1972-06-30 23:59:59.0
196 -- 1972-07-01 00:00:00.0
198 -- When a new leap second is introduced, the following steps must be
201 -- 1) Increment Leap_Seconds_Count in a-calend.adb by one
202 -- 2) Increment LS_Count in xleaps.adb by one
203 -- 3) Add the new date to the aggregate of array LS_Dates in
205 -- 4) Compile and execute xleaps
206 -- 5) Replace the values of Leap_Second_Times in a-calend.adb with the
207 -- aggregate generated by xleaps
209 -- The algorithms that build the actual leap second values and discover
210 -- how many leap seconds have occurred between two dates do not need any
213 ------------------------------
214 -- Non-leap Centennial Years --
215 ------------------------------
217 -- Over the range of Ada time, centennial years 2100, 2200 and 2300 are
218 -- non-leap. As a consequence, seven non-leap years occur over the period
219 -- of year - 4 to year + 4. Internally, routines Split and Time_Of add or
220 -- subtract a "fake" February 29 to facilitate the arithmetic involved.
222 ------------------------
223 -- Local Declarations --
224 ------------------------
226 type Time_Rep
is new Long_Long_Integer;
227 type Time
is new Time_Rep
;
228 -- The underlying type of Time has been chosen to be a 64 bit signed
229 -- integer number since it allows for easier processing of sub-seconds
230 -- and arithmetic. We use Long_Long_Integer to allow this unit to compile
231 -- when using custom target configuration files where the max integer is
232 -- 32 bits. This is useful for static analysis tools such as SPARK or
235 -- Note: the reason we have two separate types here is to avoid problems
236 -- with overloading ambiguities in the body if we tried to use Time as an
237 -- internal computational type.
239 function Epoch_Offset
return Time_Rep
;
240 pragma Inline
(Epoch_Offset
);
241 -- Return the difference between our epoch and 1970-1-1 UTC (the Unix
242 -- epoch) expressed in nanoseconds. Note that year 2100 is non-leap.
244 Days_In_Month
: constant array (Month_Number
) of Day_Number
:=
245 [31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31];
246 -- Days in month for non-leap year, leap year case is adjusted in code
248 Invalid_Time_Zone_Offset
: Long_Integer;
249 pragma Import
(C
, Invalid_Time_Zone_Offset
, "__gnat_invalid_tzoff");
251 function Is_Leap
(Year
: Year_Number
) return Boolean;
252 -- Determine whether a given year is leap
254 ----------------------------------------------------------
255 -- Target-Independent Interface to Children of Calendar --
256 ----------------------------------------------------------
258 -- The following packages provide a target-independent interface to the
259 -- children of Calendar - Arithmetic, Conversions, Delays, Formatting and
262 ---------------------------
263 -- Arithmetic_Operations --
264 ---------------------------
266 package Arithmetic_Operations
is
268 function Add
(Date
: Time
; Days
: Long_Integer) return Time
;
269 -- Add a certain number of days to a time value
274 Days
: out Long_Integer;
275 Seconds
: out Duration;
276 Leap_Seconds
: out Integer);
277 -- Calculate the difference between two time values in terms of days,
278 -- seconds and leap seconds elapsed. The leap seconds are not included
279 -- in the seconds returned. If Left is greater than Right, the returned
280 -- values are positive, negative otherwise.
282 function Subtract
(Date
: Time
; Days
: Long_Integer) return Time
;
283 -- Subtract a certain number of days from a time value
285 end Arithmetic_Operations
;
287 ---------------------------
288 -- Conversion_Operations --
289 ---------------------------
291 package Conversion_Operations
is
293 function To_Ada_Time
(Unix_Time
: Long_Integer) return Time
;
294 -- Unix to Ada Epoch conversion
303 tm_isdst
: Integer) return Time
;
304 -- Struct tm to Ada Epoch conversion
307 (tv_sec
: Long_Integer;
308 tv_nsec
: Long_Integer) return Duration;
309 -- Struct timespec to Duration conversion
311 procedure To_Struct_Timespec
313 tv_sec
: out Long_Integer;
314 tv_nsec
: out Long_Integer);
315 -- Duration to struct timespec conversion
317 procedure To_Struct_Tm
319 tm_year
: out Integer;
320 tm_mon
: out Integer;
321 tm_day
: out Integer;
322 tm_hour
: out Integer;
323 tm_min
: out Integer;
324 tm_sec
: out Integer);
325 -- Time to struct tm conversion
327 function To_Unix_Time
(Ada_Time
: Time
) return Long_Integer;
328 -- Ada to Unix Epoch conversion
330 end Conversion_Operations
;
332 ----------------------
333 -- Delay_Operations --
334 ----------------------
336 package Delay_Operations
is
338 function To_Duration
(Date
: Time
) return Duration;
339 -- Given a time value in nanoseconds since 1901, convert it into a
340 -- duration value giving the number of nanoseconds since the Unix Epoch.
342 end Delay_Operations
;
344 ---------------------------
345 -- Formatting_Operations --
346 ---------------------------
348 package Formatting_Operations
is
350 function Day_Of_Week
(Date
: Time
) return Integer;
351 -- Determine which day of week Date falls on. The returned values are
352 -- within the range of 0 .. 6 (Monday .. Sunday).
356 Year
: out Year_Number
;
357 Month
: out Month_Number
;
358 Day
: out Day_Number
;
359 Day_Secs
: out Day_Duration
;
361 Minute
: out Integer;
362 Second
: out Integer;
363 Sub_Sec
: out Duration;
364 Leap_Sec
: out Boolean;
366 Is_Historic
: Boolean;
367 Time_Zone
: Long_Integer);
368 pragma Export
(Ada
, Split
, "__gnat_split");
369 -- Split a time value into its components. If flag Is_Historic is set,
370 -- this routine would try to use to the best of the OS's abilities the
371 -- time zone offset that was or will be in effect on Date. Set Use_TZ
372 -- to use the local time zone (the value in Time_Zone is ignored) when
373 -- splitting a time value.
377 Month
: Month_Number
;
379 Day_Secs
: Day_Duration
;
385 Use_Day_Secs
: Boolean;
387 Is_Historic
: Boolean;
388 Time_Zone
: Long_Integer) return Time
;
389 pragma Export
(Ada
, Time_Of
, "__gnat_time_of");
390 -- Given all the components of a date, return the corresponding time
391 -- value. Set Use_Day_Secs to use the value in Day_Secs, otherwise the
392 -- day duration will be calculated from Hour, Minute, Second and Sub_
393 -- Sec. If flag Is_Historic is set, this routine would try to use to the
394 -- best of the OS's abilities the time zone offset that was or will be
395 -- in effect on the input date. Set Use_TZ to use the local time zone
396 -- (the value in formal Time_Zone is ignored) when building a time value
397 -- and to verify the validity of a requested leap second.
399 end Formatting_Operations
;
401 ---------------------------
402 -- Time_Zones_Operations --
403 ---------------------------
405 package Time_Zones_Operations
is
407 function UTC_Time_Offset
(Date
: Time
) return Long_Integer;
408 -- Return (in seconds) the difference between the local time zone and
409 -- UTC time at a specific historic date.
411 end Time_Zones_Operations
;