1 ------------------------------------------------------------------------------
3 -- GNAT RUN-TIME COMPONENTS --
5 -- A D A . C A L E N D A R --
9 -- Copyright (C) 1992-2009, Free Software Foundation, Inc. --
11 -- GNAT is free software; you can redistribute it and/or modify it under --
12 -- terms of the GNU General Public License as published by the Free Soft- --
13 -- ware Foundation; either version 3, or (at your option) any later ver- --
14 -- sion. GNAT is distributed in the hope that it will be useful, but WITH- --
15 -- OUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY --
16 -- or FITNESS FOR A PARTICULAR PURPOSE. --
18 -- As a special exception under Section 7 of GPL version 3, you are granted --
19 -- additional permissions described in the GCC Runtime Library Exception, --
20 -- version 3.1, as published by the Free Software Foundation. --
22 -- You should have received a copy of the GNU General Public License and --
23 -- a copy of the GCC Runtime Library Exception along with this program; --
24 -- see the files COPYING3 and COPYING.RUNTIME respectively. If not, see --
25 -- <http://www.gnu.org/licenses/>. --
27 -- GNAT was originally developed by the GNAT team at New York University. --
28 -- Extensive contributions were provided by Ada Core Technologies Inc. --
30 ------------------------------------------------------------------------------
32 with Ada.Unchecked_Conversion;
34 with System.OS_Primitives;
36 package body Ada.Calendar is
38 --------------------------
39 -- Implementation Notes --
40 --------------------------
42 -- In complex algorithms, some variables of type Ada.Calendar.Time carry
43 -- suffix _S or _N to denote units of seconds or nanoseconds.
45 -- Because time is measured in different units and from different origins
46 -- on various targets, a system independent model is incorporated into
47 -- Ada.Calendar. The idea behind the design is to encapsulate all target
48 -- dependent machinery in a single package, thus providing a uniform
49 -- interface to all existing and any potential children.
51 -- package Ada.Calendar
52 -- procedure Split (5 parameters) -------+
53 -- | Call from local routine
55 -- package Formatting_Operations |
56 -- procedure Split (11 parameters) <--+
57 -- end Formatting_Operations |
60 -- package Ada.Calendar.Formatting | Call from child routine
61 -- procedure Split (9 or 10 parameters) -+
62 -- end Ada.Calendar.Formatting
64 -- The behaviour of the interfacing routines is controlled via various
65 -- flags. All new Ada 2005 types from children of Ada.Calendar are
66 -- emulated by a similar type. For instance, type Day_Number is replaced
67 -- by Integer in various routines. One ramification of this model is that
68 -- the caller site must perform validity checks on returned results.
69 -- The end result of this model is the lack of target specific files per
70 -- child of Ada.Calendar (a-calfor, a-calfor-vms, a-calfor-vxwors, etc).
72 -----------------------
73 -- Local Subprograms --
74 -----------------------
76 procedure Check_Within_Time_Bounds (T : Time_Rep);
77 -- Ensure that a time representation value falls withing the bounds of Ada
78 -- time. Leap seconds support is taken into account.
80 procedure Cumulative_Leap_Seconds
81 (Start_Date : Time_Rep;
83 Elapsed_Leaps : out Natural;
84 Next_Leap : out Time_Rep);
85 -- Elapsed_Leaps is the sum of the leap seconds that have occurred on or
86 -- after Start_Date and before (strictly before) End_Date. Next_Leap_Sec
87 -- represents the next leap second occurrence on or after End_Date. If
88 -- there are no leaps seconds after End_Date, End_Of_Time is returned.
89 -- End_Of_Time can be used as End_Date to count all the leap seconds that
90 -- have occurred on or after Start_Date.
92 -- Note: Any sub seconds of Start_Date and End_Date are discarded before
93 -- the calculations are done. For instance: if 113 seconds is a leap
94 -- second (it isn't) and 113.5 is input as an End_Date, the leap second
95 -- at 113 will not be counted in Leaps_Between, but it will be returned
96 -- as Next_Leap_Sec. Thus, if the caller wants to know if the End_Date is
97 -- a leap second, the comparison should be:
99 -- End_Date >= Next_Leap_Sec;
101 -- After_Last_Leap is designed so that this comparison works without
102 -- having to first check if Next_Leap_Sec is a valid leap second.
104 function Duration_To_Time_Rep is
105 new Ada.Unchecked_Conversion (Duration, Time_Rep);
106 -- Convert a duration value into a time representation value
108 function Time_Rep_To_Duration is
109 new Ada.Unchecked_Conversion (Time_Rep, Duration);
110 -- Convert a time representation value into a duration value
116 -- An integer time duration. The type is used whenever a positive elapsed
117 -- duration is needed, for instance when splitting a time value. Here is
118 -- how Time_Rep and Time_Dur are related:
120 -- 'First Ada_Low Ada_High 'Last
121 -- Time_Rep: +-------+------------------------+---------+
122 -- Time_Dur: +------------------------+---------+
125 type Time_Dur is range 0 .. 2 ** 63 - 1;
127 --------------------------
128 -- Leap seconds control --
129 --------------------------
132 pragma Import (C, Flag, "__gl_leap_seconds_support");
133 -- This imported value is used to determine whether the compilation had
134 -- binder flag "-y" present which enables leap seconds. A value of zero
135 -- signifies no leap seconds support while a value of one enables the
138 Leap_Support : constant Boolean := Flag = 1;
139 -- The above flag controls the usage of leap seconds in all Ada.Calendar
142 Leap_Seconds_Count : constant Natural := 24;
144 ---------------------
145 -- Local Constants --
146 ---------------------
148 Ada_Min_Year : constant Year_Number := Year_Number'First;
149 Secs_In_Four_Years : constant := (3 * 365 + 366) * Secs_In_Day;
150 Secs_In_Non_Leap_Year : constant := 365 * Secs_In_Day;
151 Nanos_In_Four_Years : constant := Secs_In_Four_Years * Nano;
153 -- Lower and upper bound of Ada time. The zero (0) value of type Time is
154 -- positioned at year 2150. Note that the lower and upper bound account
155 -- for the non-leap centennial years.
157 Ada_Low : constant Time_Rep := -(61 * 366 + 188 * 365) * Nanos_In_Day;
158 Ada_High : constant Time_Rep := (60 * 366 + 190 * 365) * Nanos_In_Day;
160 -- Even though the upper bound of time is 2399-12-31 23:59:59.999999999
161 -- UTC, it must be increased to include all leap seconds.
163 Ada_High_And_Leaps : constant Time_Rep :=
164 Ada_High + Time_Rep (Leap_Seconds_Count) * Nano;
166 -- Two constants used in the calculations of elapsed leap seconds.
167 -- End_Of_Time is later than Ada_High in time zone -28. Start_Of_Time
168 -- is earlier than Ada_Low in time zone +28.
170 End_Of_Time : constant Time_Rep :=
171 Ada_High + Time_Rep (3) * Nanos_In_Day;
172 Start_Of_Time : constant Time_Rep :=
173 Ada_Low - Time_Rep (3) * Nanos_In_Day;
175 -- The Unix lower time bound expressed as nanoseconds since the
176 -- start of Ada time in UTC.
178 Unix_Min : constant Time_Rep :=
179 Ada_Low + Time_Rep (17 * 366 + 52 * 365) * Nanos_In_Day;
181 Epoch_Offset : constant Time_Rep := (136 * 365 + 44 * 366) * Nanos_In_Day;
182 -- The difference between 2150-1-1 UTC and 1970-1-1 UTC expressed in
183 -- nanoseconds. Note that year 2100 is non-leap.
185 Cumulative_Days_Before_Month :
186 constant array (Month_Number) of Natural :=
187 (0, 31, 59, 90, 120, 151, 181, 212, 243, 273, 304, 334);
189 -- The following table contains the hard time values of all existing leap
190 -- seconds. The values are produced by the utility program xleaps.adb.
192 Leap_Second_Times : constant array (1 .. Leap_Seconds_Count) of Time_Rep :=
193 (-5601484800000000000,
194 -5585587199000000000,
195 -5554051198000000000,
196 -5522515197000000000,
197 -5490979196000000000,
198 -5459356795000000000,
199 -5427820794000000000,
200 -5396284793000000000,
201 -5364748792000000000,
202 -5317487991000000000,
203 -5285951990000000000,
204 -5254415989000000000,
205 -5191257588000000000,
206 -5112287987000000000,
207 -5049129586000000000,
208 -5017593585000000000,
209 -4970332784000000000,
210 -4938796783000000000,
211 -4907260782000000000,
212 -4859827181000000000,
213 -4812566380000000000,
214 -4765132779000000000,
215 -4544207978000000000,
216 -4449513577000000000);
222 function "+" (Left : Time; Right : Duration) return Time is
223 pragma Unsuppress (Overflow_Check);
224 Left_N : constant Time_Rep := Time_Rep (Left);
226 return Time (Left_N + Duration_To_Time_Rep (Right));
228 when Constraint_Error =>
232 function "+" (Left : Duration; Right : Time) return Time is
241 function "-" (Left : Time; Right : Duration) return Time is
242 pragma Unsuppress (Overflow_Check);
243 Left_N : constant Time_Rep := Time_Rep (Left);
245 return Time (Left_N - Duration_To_Time_Rep (Right));
247 when Constraint_Error =>
251 function "-" (Left : Time; Right : Time) return Duration is
252 pragma Unsuppress (Overflow_Check);
254 -- The bounds of type Duration expressed as time representations
256 Dur_Low : constant Time_Rep := Duration_To_Time_Rep (Duration'First);
257 Dur_High : constant Time_Rep := Duration_To_Time_Rep (Duration'Last);
262 Res_N := Time_Rep (Left) - Time_Rep (Right);
264 -- Due to the extended range of Ada time, "-" is capable of producing
265 -- results which may exceed the range of Duration. In order to prevent
266 -- the generation of bogus values by the Unchecked_Conversion, we apply
267 -- the following check.
270 or else Res_N > Dur_High
275 return Time_Rep_To_Duration (Res_N);
277 when Constraint_Error =>
285 function "<" (Left, Right : Time) return Boolean is
287 return Time_Rep (Left) < Time_Rep (Right);
294 function "<=" (Left, Right : Time) return Boolean is
296 return Time_Rep (Left) <= Time_Rep (Right);
303 function ">" (Left, Right : Time) return Boolean is
305 return Time_Rep (Left) > Time_Rep (Right);
312 function ">=" (Left, Right : Time) return Boolean is
314 return Time_Rep (Left) >= Time_Rep (Right);
317 ------------------------------
318 -- Check_Within_Time_Bounds --
319 ------------------------------
321 procedure Check_Within_Time_Bounds (T : Time_Rep) is
324 if T < Ada_Low or else T > Ada_High_And_Leaps then
328 if T < Ada_Low or else T > Ada_High then
332 end Check_Within_Time_Bounds;
338 function Clock return Time is
339 Elapsed_Leaps : Natural;
340 Next_Leap_N : Time_Rep;
342 -- The system clock returns the time in UTC since the Unix Epoch of
343 -- 1970-01-01 00:00:00.0. We perform an origin shift to the Ada Epoch
344 -- by adding the number of nanoseconds between the two origins.
347 Duration_To_Time_Rep (System.OS_Primitives.Clock) +
351 -- If the target supports leap seconds, determine the number of leap
352 -- seconds elapsed until this moment.
355 Cumulative_Leap_Seconds
356 (Start_Of_Time, Res_N, Elapsed_Leaps, Next_Leap_N);
358 -- The system clock may fall exactly on a leap second
360 if Res_N >= Next_Leap_N then
361 Elapsed_Leaps := Elapsed_Leaps + 1;
364 -- The target does not support leap seconds
370 Res_N := Res_N + Time_Rep (Elapsed_Leaps) * Nano;
375 -----------------------------
376 -- Cumulative_Leap_Seconds --
377 -----------------------------
379 procedure Cumulative_Leap_Seconds
380 (Start_Date : Time_Rep;
382 Elapsed_Leaps : out Natural;
383 Next_Leap : out Time_Rep)
385 End_Index : Positive;
386 End_T : Time_Rep := End_Date;
387 Start_Index : Positive;
388 Start_T : Time_Rep := Start_Date;
391 -- Both input dates must be normalized to UTC
393 pragma Assert (Leap_Support and then End_Date >= Start_Date);
395 Next_Leap := End_Of_Time;
397 -- Make sure that the end date does not exceed the upper bound
400 if End_Date > Ada_High then
404 -- Remove the sub seconds from both dates
406 Start_T := Start_T - (Start_T mod Nano);
407 End_T := End_T - (End_T mod Nano);
409 -- Some trivial cases:
410 -- Leap 1 . . . Leap N
411 -- ---+========+------+############+-------+========+-----
412 -- Start_T End_T Start_T End_T
414 if End_T < Leap_Second_Times (1) then
416 Next_Leap := Leap_Second_Times (1);
419 elsif Start_T > Leap_Second_Times (Leap_Seconds_Count) then
421 Next_Leap := End_Of_Time;
425 -- Perform the calculations only if the start date is within the leap
426 -- second occurrences table.
428 if Start_T <= Leap_Second_Times (Leap_Seconds_Count) then
431 -- +----+----+-- . . . --+-------+---+
432 -- | T1 | T2 | | N - 1 | N |
433 -- +----+----+-- . . . --+-------+---+
435 -- | Start_Index | End_Index
436 -- +-------------------+
439 -- The idea behind the algorithm is to iterate and find two
440 -- closest dates which are after Start_T and End_T. Their
441 -- corresponding index difference denotes the number of leap
446 exit when Leap_Second_Times (Start_Index) >= Start_T;
447 Start_Index := Start_Index + 1;
450 End_Index := Start_Index;
452 exit when End_Index > Leap_Seconds_Count
453 or else Leap_Second_Times (End_Index) >= End_T;
454 End_Index := End_Index + 1;
457 if End_Index <= Leap_Seconds_Count then
458 Next_Leap := Leap_Second_Times (End_Index);
461 Elapsed_Leaps := End_Index - Start_Index;
466 end Cumulative_Leap_Seconds;
472 function Day (Date : Time) return Day_Number is
477 pragma Unreferenced (Y, M, S);
479 Split (Date, Y, M, D, S);
487 function Is_Leap (Year : Year_Number) return Boolean is
489 -- Leap centennial years
491 if Year mod 400 = 0 then
494 -- Non-leap centennial years
496 elsif Year mod 100 = 0 then
502 return Year mod 4 = 0;
510 function Month (Date : Time) return Month_Number is
515 pragma Unreferenced (Y, D, S);
517 Split (Date, Y, M, D, S);
525 function Seconds (Date : Time) return Day_Duration is
530 pragma Unreferenced (Y, M, D);
532 Split (Date, Y, M, D, S);
542 Year : out Year_Number;
543 Month : out Month_Number;
544 Day : out Day_Number;
545 Seconds : out Day_Duration)
553 pragma Unreferenced (H, M, Se, Ss, Le);
556 -- Even though the input time zone is UTC (0), the flag Is_Ada_05 will
557 -- ensure that Split picks up the local time zone.
559 Formatting_Operations.Split
576 or else not Month'Valid
577 or else not Day'Valid
578 or else not Seconds'Valid
590 Month : Month_Number;
592 Seconds : Day_Duration := 0.0) return Time
594 -- The values in the following constants are irrelevant, they are just
595 -- placeholders; the choice of constructing a Day_Duration value is
596 -- controlled by the Use_Day_Secs flag.
598 H : constant Integer := 1;
599 M : constant Integer := 1;
600 Se : constant Integer := 1;
601 Ss : constant Duration := 0.1;
607 or else not Month'Valid
608 or else not Day'Valid
609 or else not Seconds'Valid
614 -- Even though the input time zone is UTC (0), the flag Is_Ada_05 will
615 -- ensure that Split picks up the local time zone.
618 Formatting_Operations.Time_Of
628 Use_Day_Secs => True,
637 function Year (Date : Time) return Year_Number is
642 pragma Unreferenced (M, D, S);
644 Split (Date, Y, M, D, S);
648 -- The following packages assume that Time is a signed 64 bit integer
649 -- type, the units are nanoseconds and the origin is the start of Ada
650 -- time (1901-01-01 00:00:00.0 UTC).
652 ---------------------------
653 -- Arithmetic_Operations --
654 ---------------------------
656 package body Arithmetic_Operations is
662 function Add (Date : Time; Days : Long_Integer) return Time is
663 pragma Unsuppress (Overflow_Check);
664 Date_N : constant Time_Rep := Time_Rep (Date);
666 return Time (Date_N + Time_Rep (Days) * Nanos_In_Day);
668 when Constraint_Error =>
679 Days : out Long_Integer;
680 Seconds : out Duration;
681 Leap_Seconds : out Integer)
685 Elapsed_Leaps : Natural;
687 Negate : Boolean := False;
688 Next_Leap_N : Time_Rep;
690 Sub_Secs_Diff : Time_Rep;
693 -- Both input time values are assumed to be in UTC
695 if Left >= Right then
696 Later := Time_Rep (Left);
697 Earlier := Time_Rep (Right);
699 Later := Time_Rep (Right);
700 Earlier := Time_Rep (Left);
704 -- If the target supports leap seconds, process them
707 Cumulative_Leap_Seconds
708 (Earlier, Later, Elapsed_Leaps, Next_Leap_N);
710 if Later >= Next_Leap_N then
711 Elapsed_Leaps := Elapsed_Leaps + 1;
714 -- The target does not support leap seconds
720 -- Sub seconds processing. We add the resulting difference to one
721 -- of the input dates in order to account for any potential rounding
722 -- of the difference in the next step.
724 Sub_Secs_Diff := Later mod Nano - Earlier mod Nano;
725 Earlier := Earlier + Sub_Secs_Diff;
726 Sub_Secs := Duration (Sub_Secs_Diff) / Nano_F;
728 -- Difference processing. This operation should be able to calculate
729 -- the difference between opposite values which are close to the end
730 -- and start of Ada time. To accommodate the large range, we convert
731 -- to seconds. This action may potentially round the two values and
732 -- either add or drop a second. We compensate for this issue in the
736 Time_Dur (Later / Nano - Earlier / Nano) - Time_Dur (Elapsed_Leaps);
738 Days := Long_Integer (Res_Dur / Secs_In_Day);
739 Seconds := Duration (Res_Dur mod Secs_In_Day) + Sub_Secs;
740 Leap_Seconds := Integer (Elapsed_Leaps);
746 if Leap_Seconds /= 0 then
747 Leap_Seconds := -Leap_Seconds;
756 function Subtract (Date : Time; Days : Long_Integer) return Time is
757 pragma Unsuppress (Overflow_Check);
758 Date_N : constant Time_Rep := Time_Rep (Date);
760 return Time (Date_N - Time_Rep (Days) * Nanos_In_Day);
762 when Constraint_Error =>
766 end Arithmetic_Operations;
768 ---------------------------
769 -- Conversion_Operations --
770 ---------------------------
772 package body Conversion_Operations is
778 function To_Ada_Time (Unix_Time : Long_Integer) return Time is
779 pragma Unsuppress (Overflow_Check);
780 Unix_Rep : constant Time_Rep := Time_Rep (Unix_Time) * Nano;
782 return Time (Unix_Rep - Epoch_Offset);
784 when Constraint_Error =>
799 tm_isdst : Integer) return Time
801 pragma Unsuppress (Overflow_Check);
803 Month : Month_Number;
812 Year := Year_Number (1900 + tm_year);
813 Month := Month_Number (1 + tm_mon);
814 Day := Day_Number (tm_day);
816 -- Step 1: Validity checks of input values
819 or else not Month'Valid
820 or else not Day'Valid
821 or else tm_hour not in 0 .. 24
822 or else tm_min not in 0 .. 59
823 or else tm_sec not in 0 .. 60
824 or else tm_isdst not in -1 .. 1
829 -- Step 2: Potential leap second
839 -- Step 3: Calculate the time value
843 (Formatting_Operations.Time_Of
847 Day_Secs => 0.0, -- Time is given in h:m:s
851 Sub_Sec => 0.0, -- No precise sub second given
853 Use_Day_Secs => False, -- Time is given in h:m:s
854 Is_Ada_05 => True, -- Force usage of explicit time zone
855 Time_Zone => 0)); -- Place the value in UTC
857 -- Step 4: Daylight Savings Time
860 Result := Result + Time_Rep (3_600) * Nano;
863 return Time (Result);
866 when Constraint_Error =>
875 (tv_sec : Long_Integer;
876 tv_nsec : Long_Integer) return Duration
878 pragma Unsuppress (Overflow_Check);
880 return Duration (tv_sec) + Duration (tv_nsec) / Nano_F;
883 ------------------------
884 -- To_Struct_Timespec --
885 ------------------------
887 procedure To_Struct_Timespec
889 tv_sec : out Long_Integer;
890 tv_nsec : out Long_Integer)
892 pragma Unsuppress (Overflow_Check);
894 Nano_Secs : Duration;
897 -- Seconds extraction, avoid potential rounding errors
900 tv_sec := Long_Integer (Secs);
902 -- Nanoseconds extraction
904 Nano_Secs := D - Duration (tv_sec);
905 tv_nsec := Long_Integer (Nano_Secs * Nano);
906 end To_Struct_Timespec;
912 procedure To_Struct_Tm
914 tm_year : out Integer;
915 tm_mon : out Integer;
916 tm_day : out Integer;
917 tm_hour : out Integer;
918 tm_min : out Integer;
919 tm_sec : out Integer)
921 pragma Unsuppress (Overflow_Check);
923 Month : Month_Number;
925 Day_Secs : Day_Duration;
930 -- Step 1: Split the input time
932 Formatting_Operations.Split
933 (T, Year, Month, tm_day, Day_Secs,
934 tm_hour, tm_min, Second, Sub_Sec, Leap_Sec, True, 0);
936 -- Step 2: Correct the year and month
938 tm_year := Year - 1900;
941 -- Step 3: Handle leap second occurrences
943 tm_sec := (if Leap_Sec then 60 else Second);
950 function To_Unix_Time (Ada_Time : Time) return Long_Integer is
951 pragma Unsuppress (Overflow_Check);
952 Ada_Rep : constant Time_Rep := Time_Rep (Ada_Time);
954 return Long_Integer ((Ada_Rep + Epoch_Offset) / Nano);
956 when Constraint_Error =>
959 end Conversion_Operations;
961 ----------------------
962 -- Delay_Operations --
963 ----------------------
965 package body Delay_Operations is
971 function To_Duration (Date : Time) return Duration is
972 pragma Unsuppress (Overflow_Check);
974 Safe_Ada_High : constant Time_Rep := Ada_High - Epoch_Offset;
975 -- This value represents a "safe" end of time. In order to perform a
976 -- proper conversion to Unix duration, we will have to shift origins
977 -- at one point. For very distant dates, this means an overflow check
978 -- failure. To prevent this, the function returns the "safe" end of
979 -- time (roughly 2219) which is still distant enough.
981 Elapsed_Leaps : Natural;
982 Next_Leap_N : Time_Rep;
986 Res_N := Time_Rep (Date);
988 -- Step 1: If the target supports leap seconds, remove any leap
989 -- seconds elapsed up to the input date.
992 Cumulative_Leap_Seconds
993 (Start_Of_Time, Res_N, Elapsed_Leaps, Next_Leap_N);
995 -- The input time value may fall on a leap second occurrence
997 if Res_N >= Next_Leap_N then
998 Elapsed_Leaps := Elapsed_Leaps + 1;
1001 -- The target does not support leap seconds
1007 Res_N := Res_N - Time_Rep (Elapsed_Leaps) * Nano;
1009 -- Step 2: Perform a shift in origins to obtain a Unix equivalent of
1010 -- the input. Guard against very large delay values such as the end
1011 -- of time since the computation will overflow.
1013 Res_N := (if Res_N > Safe_Ada_High then Safe_Ada_High
1014 else Res_N + Epoch_Offset);
1016 return Time_Rep_To_Duration (Res_N);
1019 end Delay_Operations;
1021 ---------------------------
1022 -- Formatting_Operations --
1023 ---------------------------
1025 package body Formatting_Operations is
1031 function Day_Of_Week (Date : Time) return Integer is
1042 pragma Unreferenced (Ds, H, Mi, Se, Su, Le);
1044 Day_Count : Long_Integer;
1049 Formatting_Operations.Split
1063 -- Build a time value in the middle of the same day
1067 (Formatting_Operations.Time_Of
1077 Use_Day_Secs => False,
1081 -- Determine the elapsed seconds since the start of Ada time
1083 Res_Dur := Time_Dur (Res_N / Nano - Ada_Low / Nano);
1085 -- Count the number of days since the start of Ada time. 1901-1-1
1086 -- GMT was a Tuesday.
1088 Day_Count := Long_Integer (Res_Dur / Secs_In_Day) + 1;
1090 return Integer (Day_Count mod 7);
1099 Year : out Year_Number;
1100 Month : out Month_Number;
1101 Day : out Day_Number;
1102 Day_Secs : out Day_Duration;
1104 Minute : out Integer;
1105 Second : out Integer;
1106 Sub_Sec : out Duration;
1107 Leap_Sec : out Boolean;
1108 Is_Ada_05 : Boolean;
1109 Time_Zone : Long_Integer)
1111 -- The following constants represent the number of nanoseconds
1112 -- elapsed since the start of Ada time to and including the non
1113 -- leap centennial years.
1115 Year_2101 : constant Time_Rep := Ada_Low +
1116 Time_Rep (49 * 366 + 151 * 365) * Nanos_In_Day;
1117 Year_2201 : constant Time_Rep := Ada_Low +
1118 Time_Rep (73 * 366 + 227 * 365) * Nanos_In_Day;
1119 Year_2301 : constant Time_Rep := Ada_Low +
1120 Time_Rep (97 * 366 + 303 * 365) * Nanos_In_Day;
1122 Date_Dur : Time_Dur;
1124 Day_Seconds : Natural;
1125 Elapsed_Leaps : Natural;
1126 Four_Year_Segs : Natural;
1127 Hour_Seconds : Natural;
1128 Is_Leap_Year : Boolean;
1129 Next_Leap_N : Time_Rep;
1130 Rem_Years : Natural;
1131 Sub_Sec_N : Time_Rep;
1135 Date_N := Time_Rep (Date);
1137 -- Step 1: Leap seconds processing in UTC
1139 if Leap_Support then
1140 Cumulative_Leap_Seconds
1141 (Start_Of_Time, Date_N, Elapsed_Leaps, Next_Leap_N);
1143 Leap_Sec := Date_N >= Next_Leap_N;
1146 Elapsed_Leaps := Elapsed_Leaps + 1;
1149 -- The target does not support leap seconds
1156 Date_N := Date_N - Time_Rep (Elapsed_Leaps) * Nano;
1158 -- Step 2: Time zone processing. This action converts the input date
1159 -- from GMT to the requested time zone.
1162 if Time_Zone /= 0 then
1163 Date_N := Date_N + Time_Rep (Time_Zone) * 60 * Nano;
1170 Off : constant Long_Integer :=
1171 Time_Zones_Operations.UTC_Time_Offset (Time (Date_N));
1173 Date_N := Date_N + Time_Rep (Off) * Nano;
1177 -- Step 3: Non-leap centennial year adjustment in local time zone
1179 -- In order for all divisions to work properly and to avoid more
1180 -- complicated arithmetic, we add fake February 29s to dates which
1181 -- occur after a non-leap centennial year.
1183 if Date_N >= Year_2301 then
1184 Date_N := Date_N + Time_Rep (3) * Nanos_In_Day;
1186 elsif Date_N >= Year_2201 then
1187 Date_N := Date_N + Time_Rep (2) * Nanos_In_Day;
1189 elsif Date_N >= Year_2101 then
1190 Date_N := Date_N + Time_Rep (1) * Nanos_In_Day;
1193 -- Step 4: Sub second processing in local time zone
1195 Sub_Sec_N := Date_N mod Nano;
1196 Sub_Sec := Duration (Sub_Sec_N) / Nano_F;
1197 Date_N := Date_N - Sub_Sec_N;
1199 -- Convert Date_N into a time duration value, changing the units
1202 Date_Dur := Time_Dur (Date_N / Nano - Ada_Low / Nano);
1204 -- Step 5: Year processing in local time zone. Determine the number
1205 -- of four year segments since the start of Ada time and the input
1208 Four_Year_Segs := Natural (Date_Dur / Secs_In_Four_Years);
1210 if Four_Year_Segs > 0 then
1211 Date_Dur := Date_Dur - Time_Dur (Four_Year_Segs) *
1215 -- Calculate the remaining non-leap years
1217 Rem_Years := Natural (Date_Dur / Secs_In_Non_Leap_Year);
1219 if Rem_Years > 3 then
1223 Date_Dur := Date_Dur - Time_Dur (Rem_Years) * Secs_In_Non_Leap_Year;
1225 Year := Ada_Min_Year + Natural (4 * Four_Year_Segs + Rem_Years);
1226 Is_Leap_Year := Is_Leap (Year);
1228 -- Step 6: Month and day processing in local time zone
1230 Year_Day := Natural (Date_Dur / Secs_In_Day) + 1;
1234 -- Processing for months after January
1236 if Year_Day > 31 then
1238 Year_Day := Year_Day - 31;
1240 -- Processing for a new month or a leap February
1243 and then (not Is_Leap_Year or else Year_Day > 29)
1246 Year_Day := Year_Day - 28;
1248 if Is_Leap_Year then
1249 Year_Day := Year_Day - 1;
1254 while Year_Day > Days_In_Month (Month) loop
1255 Year_Day := Year_Day - Days_In_Month (Month);
1261 -- Step 7: Hour, minute, second and sub second processing in local
1264 Day := Day_Number (Year_Day);
1265 Day_Seconds := Integer (Date_Dur mod Secs_In_Day);
1266 Day_Secs := Duration (Day_Seconds) + Sub_Sec;
1267 Hour := Day_Seconds / 3_600;
1268 Hour_Seconds := Day_Seconds mod 3_600;
1269 Minute := Hour_Seconds / 60;
1270 Second := Hour_Seconds mod 60;
1278 (Year : Year_Number;
1279 Month : Month_Number;
1281 Day_Secs : Day_Duration;
1286 Leap_Sec : Boolean := False;
1287 Use_Day_Secs : Boolean := False;
1288 Is_Ada_05 : Boolean := False;
1289 Time_Zone : Long_Integer := 0) return Time
1292 Elapsed_Leaps : Natural;
1293 Next_Leap_N : Time_Rep;
1295 Rounded_Res_N : Time_Rep;
1298 -- Step 1: Check whether the day, month and year form a valid date
1300 if Day > Days_In_Month (Month)
1301 and then (Day /= 29 or else Month /= 2 or else not Is_Leap (Year))
1306 -- Start accumulating nanoseconds from the low bound of Ada time
1310 -- Step 2: Year processing and centennial year adjustment. Determine
1311 -- the number of four year segments since the start of Ada time and
1314 Count := (Year - Year_Number'First) / 4;
1315 for Four_Year_Segments in 1 .. Count loop
1316 Res_N := Res_N + Nanos_In_Four_Years;
1319 -- Note that non-leap centennial years are automatically considered
1320 -- leap in the operation above. An adjustment of several days is
1321 -- required to compensate for this.
1324 Res_N := Res_N - Time_Rep (3) * Nanos_In_Day;
1326 elsif Year > 2200 then
1327 Res_N := Res_N - Time_Rep (2) * Nanos_In_Day;
1329 elsif Year > 2100 then
1330 Res_N := Res_N - Time_Rep (1) * Nanos_In_Day;
1333 -- Add the remaining non-leap years
1335 Count := (Year - Year_Number'First) mod 4;
1336 Res_N := Res_N + Time_Rep (Count) * Secs_In_Non_Leap_Year * Nano;
1338 -- Step 3: Day of month processing. Determine the number of days
1339 -- since the start of the current year. Do not add the current
1340 -- day since it has not elapsed yet.
1342 Count := Cumulative_Days_Before_Month (Month) + Day - 1;
1344 -- The input year is leap and we have passed February
1352 Res_N := Res_N + Time_Rep (Count) * Nanos_In_Day;
1354 -- Step 4: Hour, minute, second and sub second processing
1356 if Use_Day_Secs then
1357 Res_N := Res_N + Duration_To_Time_Rep (Day_Secs);
1361 Res_N + Time_Rep (Hour * 3_600 + Minute * 60 + Second) * Nano;
1363 if Sub_Sec = 1.0 then
1364 Res_N := Res_N + Time_Rep (1) * Nano;
1366 Res_N := Res_N + Duration_To_Time_Rep (Sub_Sec);
1370 -- At this point, the generated time value should be withing the
1371 -- bounds of Ada time.
1373 Check_Within_Time_Bounds (Res_N);
1375 -- Step 4: Time zone processing. At this point we have built an
1376 -- arbitrary time value which is not related to any time zone.
1377 -- For simplicity, the time value is normalized to GMT, producing
1378 -- a uniform representation which can be treated by arithmetic
1379 -- operations for instance without any additional corrections.
1382 if Time_Zone /= 0 then
1383 Res_N := Res_N - Time_Rep (Time_Zone) * 60 * Nano;
1390 Current_Off : constant Long_Integer :=
1391 Time_Zones_Operations.UTC_Time_Offset
1393 Current_Res_N : constant Time_Rep :=
1394 Res_N - Time_Rep (Current_Off) * Nano;
1395 Off : constant Long_Integer :=
1396 Time_Zones_Operations.UTC_Time_Offset
1397 (Time (Current_Res_N));
1399 Res_N := Res_N - Time_Rep (Off) * Nano;
1403 -- Step 5: Leap seconds processing in GMT
1405 if Leap_Support then
1406 Cumulative_Leap_Seconds
1407 (Start_Of_Time, Res_N, Elapsed_Leaps, Next_Leap_N);
1409 Res_N := Res_N + Time_Rep (Elapsed_Leaps) * Nano;
1411 -- An Ada 2005 caller requesting an explicit leap second or an
1412 -- Ada 95 caller accounting for an invisible leap second.
1415 or else Res_N >= Next_Leap_N
1417 Res_N := Res_N + Time_Rep (1) * Nano;
1420 -- Leap second validity check
1422 Rounded_Res_N := Res_N - (Res_N mod Nano);
1426 and then Rounded_Res_N /= Next_Leap_N
1432 return Time (Res_N);
1435 end Formatting_Operations;
1437 ---------------------------
1438 -- Time_Zones_Operations --
1439 ---------------------------
1441 package body Time_Zones_Operations is
1443 -- The Unix time bounds in nanoseconds: 1970/1/1 .. 2037/1/1
1445 Unix_Min : constant Time_Rep := Ada_Low +
1446 Time_Rep (17 * 366 + 52 * 365) * Nanos_In_Day;
1448 Unix_Max : constant Time_Rep := Ada_Low +
1449 Time_Rep (34 * 366 + 102 * 365) * Nanos_In_Day +
1450 Time_Rep (Leap_Seconds_Count) * Nano;
1452 -- The following constants denote February 28 during non-leap
1453 -- centennial years, the units are nanoseconds.
1455 T_2100_2_28 : constant Time_Rep := Ada_Low +
1456 (Time_Rep (49 * 366 + 150 * 365 + 59) * Secs_In_Day +
1457 Time_Rep (Leap_Seconds_Count)) * Nano;
1459 T_2200_2_28 : constant Time_Rep := Ada_Low +
1460 (Time_Rep (73 * 366 + 226 * 365 + 59) * Secs_In_Day +
1461 Time_Rep (Leap_Seconds_Count)) * Nano;
1463 T_2300_2_28 : constant Time_Rep := Ada_Low +
1464 (Time_Rep (97 * 366 + 302 * 365 + 59) * Secs_In_Day +
1465 Time_Rep (Leap_Seconds_Count)) * Nano;
1467 -- 56 years (14 leap years + 42 non leap years) in nanoseconds:
1469 Nanos_In_56_Years : constant := (14 * 366 + 42 * 365) * Nanos_In_Day;
1471 subtype long is Long_Integer;
1472 type long_Pointer is access all long;
1475 range -(2 ** (Standard'Address_Size - Integer'(1))) ..
1476 +(2 ** (Standard'Address_Size - Integer'(1)) - 1);
1477 type time_t_Pointer is access all time_t;
1479 procedure localtime_tzoff
1480 (timer : time_t_Pointer;
1481 off : long_Pointer);
1482 pragma Import (C, localtime_tzoff, "__gnat_localtime_tzoff");
1483 -- This is a lightweight wrapper around the system library function
1484 -- localtime_r. Parameter 'off' captures the UTC offset which is either
1485 -- retrieved from the tm struct or calculated from the 'timezone' extern
1486 -- and the tm_isdst flag in the tm struct.
1488 ---------------------
1489 -- UTC_Time_Offset --
1490 ---------------------
1492 function UTC_Time_Offset (Date : Time) return Long_Integer is
1495 Offset : aliased long;
1496 Secs_T : aliased time_t;
1499 Date_N := Time_Rep (Date);
1501 -- Dates which are 56 years apart fall on the same day, day light
1502 -- saving and so on. Non-leap centennial years violate this rule by
1503 -- one day and as a consequence, special adjustment is needed.
1506 (if Date_N <= T_2100_2_28 then 0
1507 elsif Date_N <= T_2200_2_28 then 1
1508 elsif Date_N <= T_2300_2_28 then 2
1511 if Adj_Cent > 0 then
1512 Date_N := Date_N - Time_Rep (Adj_Cent) * Nanos_In_Day;
1515 -- Shift the date within bounds of Unix time
1517 while Date_N < Unix_Min loop
1518 Date_N := Date_N + Nanos_In_56_Years;
1521 while Date_N >= Unix_Max loop
1522 Date_N := Date_N - Nanos_In_56_Years;
1525 -- Perform a shift in origins from Ada to Unix
1527 Date_N := Date_N - Unix_Min;
1529 -- Convert the date into seconds
1531 Secs_T := time_t (Date_N / Nano);
1534 (Secs_T'Unchecked_Access,
1535 Offset'Unchecked_Access);
1538 end UTC_Time_Offset;
1540 end Time_Zones_Operations;
1542 -- Start of elaboration code for Ada.Calendar
1545 System.OS_Primitives.Initialize;