1 ------------------------------------------------------------------------------
3 -- GNAT RUN-TIME COMPONENTS --
5 -- A D A . C A L E N D A R --
9 -- Copyright (C) 1992-2012, 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 support.
137 Leap_Support : constant Boolean := (Flag = 1);
138 -- Flag to controls the usage of leap seconds in all Ada.Calendar routines
140 Leap_Seconds_Count : constant Natural := 24;
142 ---------------------
143 -- Local Constants --
144 ---------------------
146 Ada_Min_Year : constant Year_Number := Year_Number'First;
147 Secs_In_Four_Years : constant := (3 * 365 + 366) * Secs_In_Day;
148 Secs_In_Non_Leap_Year : constant := 365 * Secs_In_Day;
149 Nanos_In_Four_Years : constant := Secs_In_Four_Years * Nano;
151 -- Lower and upper bound of Ada time. The zero (0) value of type Time is
152 -- positioned at year 2150. Note that the lower and upper bound account
153 -- for the non-leap centennial years.
155 Ada_Low : constant Time_Rep := -(61 * 366 + 188 * 365) * Nanos_In_Day;
156 Ada_High : constant Time_Rep := (60 * 366 + 190 * 365) * Nanos_In_Day;
158 -- Even though the upper bound of time is 2399-12-31 23:59:59.999999999
159 -- UTC, it must be increased to include all leap seconds.
161 Ada_High_And_Leaps : constant Time_Rep :=
162 Ada_High + Time_Rep (Leap_Seconds_Count) * Nano;
164 -- Two constants used in the calculations of elapsed leap seconds.
165 -- End_Of_Time is later than Ada_High in time zone -28. Start_Of_Time
166 -- is earlier than Ada_Low in time zone +28.
168 End_Of_Time : constant Time_Rep :=
169 Ada_High + Time_Rep (3) * Nanos_In_Day;
170 Start_Of_Time : constant Time_Rep :=
171 Ada_Low - Time_Rep (3) * Nanos_In_Day;
173 -- The Unix lower time bound expressed as nanoseconds since the start of
176 Unix_Min : constant Time_Rep :=
177 Ada_Low + Time_Rep (17 * 366 + 52 * 365) * Nanos_In_Day;
179 Epoch_Offset : constant Time_Rep := (136 * 365 + 44 * 366) * Nanos_In_Day;
180 -- The difference between 2150-1-1 UTC and 1970-1-1 UTC expressed in
181 -- nanoseconds. Note that year 2100 is non-leap.
183 Cumulative_Days_Before_Month :
184 constant array (Month_Number) of Natural :=
185 (0, 31, 59, 90, 120, 151, 181, 212, 243, 273, 304, 334);
187 -- The following table contains the hard time values of all existing leap
188 -- seconds. The values are produced by the utility program xleaps.adb. This
189 -- must be updated when additional leap second times are defined.
191 Leap_Second_Times : constant array (1 .. Leap_Seconds_Count) of Time_Rep :=
192 (-5601484800000000000,
193 -5585587199000000000,
194 -5554051198000000000,
195 -5522515197000000000,
196 -5490979196000000000,
197 -5459356795000000000,
198 -5427820794000000000,
199 -5396284793000000000,
200 -5364748792000000000,
201 -5317487991000000000,
202 -5285951990000000000,
203 -5254415989000000000,
204 -5191257588000000000,
205 -5112287987000000000,
206 -5049129586000000000,
207 -5017593585000000000,
208 -4970332784000000000,
209 -4938796783000000000,
210 -4907260782000000000,
211 -4859827181000000000,
212 -4812566380000000000,
213 -4765132779000000000,
214 -4544207978000000000,
215 -4449513577000000000);
221 function "+" (Left : Time; Right : Duration) return Time is
222 pragma Unsuppress (Overflow_Check);
223 Left_N : constant Time_Rep := Time_Rep (Left);
225 return Time (Left_N + Duration_To_Time_Rep (Right));
227 when Constraint_Error =>
231 function "+" (Left : Duration; Right : Time) return Time is
240 function "-" (Left : Time; Right : Duration) return Time is
241 pragma Unsuppress (Overflow_Check);
242 Left_N : constant Time_Rep := Time_Rep (Left);
244 return Time (Left_N - Duration_To_Time_Rep (Right));
246 when Constraint_Error =>
250 function "-" (Left : Time; Right : Time) return Duration is
251 pragma Unsuppress (Overflow_Check);
253 Dur_Low : constant Time_Rep := Duration_To_Time_Rep (Duration'First);
254 Dur_High : constant Time_Rep := Duration_To_Time_Rep (Duration'Last);
255 -- The bounds of type Duration expressed as time representations
260 Res_N := Time_Rep (Left) - Time_Rep (Right);
262 -- Due to the extended range of Ada time, "-" is capable of producing
263 -- results which may exceed the range of Duration. In order to prevent
264 -- the generation of bogus values by the Unchecked_Conversion, we apply
265 -- the following check.
267 if Res_N < Dur_Low or else Res_N > Dur_High then
271 return Time_Rep_To_Duration (Res_N);
274 when Constraint_Error =>
282 function "<" (Left, Right : Time) return Boolean is
284 return Time_Rep (Left) < Time_Rep (Right);
291 function "<=" (Left, Right : Time) return Boolean is
293 return Time_Rep (Left) <= Time_Rep (Right);
300 function ">" (Left, Right : Time) return Boolean is
302 return Time_Rep (Left) > Time_Rep (Right);
309 function ">=" (Left, Right : Time) return Boolean is
311 return Time_Rep (Left) >= Time_Rep (Right);
314 ------------------------------
315 -- Check_Within_Time_Bounds --
316 ------------------------------
318 procedure Check_Within_Time_Bounds (T : Time_Rep) is
321 if T < Ada_Low or else T > Ada_High_And_Leaps then
325 if T < Ada_Low or else T > Ada_High then
329 end Check_Within_Time_Bounds;
335 function Clock return Time is
336 Elapsed_Leaps : Natural;
337 Next_Leap_N : Time_Rep;
339 -- The system clock returns the time in UTC since the Unix Epoch of
340 -- 1970-01-01 00:00:00.0. We perform an origin shift to the Ada Epoch
341 -- by adding the number of nanoseconds between the two origins.
344 Duration_To_Time_Rep (System.OS_Primitives.Clock) + Unix_Min;
347 -- If the target supports leap seconds, determine the number of leap
348 -- seconds elapsed until this moment.
351 Cumulative_Leap_Seconds
352 (Start_Of_Time, Res_N, Elapsed_Leaps, Next_Leap_N);
354 -- The system clock may fall exactly on a leap second
356 if Res_N >= Next_Leap_N then
357 Elapsed_Leaps := Elapsed_Leaps + 1;
360 -- The target does not support leap seconds
366 Res_N := Res_N + Time_Rep (Elapsed_Leaps) * Nano;
371 -----------------------------
372 -- Cumulative_Leap_Seconds --
373 -----------------------------
375 procedure Cumulative_Leap_Seconds
376 (Start_Date : Time_Rep;
378 Elapsed_Leaps : out Natural;
379 Next_Leap : out Time_Rep)
381 End_Index : Positive;
382 End_T : Time_Rep := End_Date;
383 Start_Index : Positive;
384 Start_T : Time_Rep := Start_Date;
387 -- Both input dates must be normalized to UTC
389 pragma Assert (Leap_Support and then End_Date >= Start_Date);
391 Next_Leap := End_Of_Time;
393 -- Make sure that the end date does not exceed the upper bound
396 if End_Date > Ada_High then
400 -- Remove the sub seconds from both dates
402 Start_T := Start_T - (Start_T mod Nano);
403 End_T := End_T - (End_T mod Nano);
405 -- Some trivial cases:
406 -- Leap 1 . . . Leap N
407 -- ---+========+------+############+-------+========+-----
408 -- Start_T End_T Start_T End_T
410 if End_T < Leap_Second_Times (1) then
412 Next_Leap := Leap_Second_Times (1);
415 elsif Start_T > Leap_Second_Times (Leap_Seconds_Count) then
417 Next_Leap := End_Of_Time;
421 -- Perform the calculations only if the start date is within the leap
422 -- second occurrences table.
424 if Start_T <= Leap_Second_Times (Leap_Seconds_Count) then
427 -- +----+----+-- . . . --+-------+---+
428 -- | T1 | T2 | | N - 1 | N |
429 -- +----+----+-- . . . --+-------+---+
431 -- | Start_Index | End_Index
432 -- +-------------------+
435 -- The idea behind the algorithm is to iterate and find two
436 -- closest dates which are after Start_T and End_T. Their
437 -- corresponding index difference denotes the number of leap
442 exit when Leap_Second_Times (Start_Index) >= Start_T;
443 Start_Index := Start_Index + 1;
446 End_Index := Start_Index;
448 exit when End_Index > Leap_Seconds_Count
449 or else Leap_Second_Times (End_Index) >= End_T;
450 End_Index := End_Index + 1;
453 if End_Index <= Leap_Seconds_Count then
454 Next_Leap := Leap_Second_Times (End_Index);
457 Elapsed_Leaps := End_Index - Start_Index;
462 end Cumulative_Leap_Seconds;
468 function Day (Date : Time) return Day_Number is
473 pragma Unreferenced (Y, M, S);
475 Split (Date, Y, M, D, S);
483 function Is_Leap (Year : Year_Number) return Boolean is
485 -- Leap centennial years
487 if Year mod 400 = 0 then
490 -- Non-leap centennial years
492 elsif Year mod 100 = 0 then
498 return Year mod 4 = 0;
506 function Month (Date : Time) return Month_Number is
511 pragma Unreferenced (Y, D, S);
513 Split (Date, Y, M, D, S);
521 function Seconds (Date : Time) return Day_Duration is
526 pragma Unreferenced (Y, M, D);
528 Split (Date, Y, M, D, S);
538 Year : out Year_Number;
539 Month : out Month_Number;
540 Day : out Day_Number;
541 Seconds : out Day_Duration)
549 pragma Unreferenced (H, M, Se, Ss, Le);
552 -- Even though the input time zone is UTC (0), the flag Is_Ada_05 will
553 -- ensure that Split picks up the local time zone.
555 Formatting_Operations.Split
571 if not Year'Valid or else
572 not Month'Valid or else
573 not Day'Valid or else
586 Month : Month_Number;
588 Seconds : Day_Duration := 0.0) return Time
590 -- The values in the following constants are irrelevant, they are just
591 -- placeholders; the choice of constructing a Day_Duration value is
592 -- controlled by the Use_Day_Secs flag.
594 H : constant Integer := 1;
595 M : constant Integer := 1;
596 Se : constant Integer := 1;
597 Ss : constant Duration := 0.1;
602 if not Year'Valid or else
603 not Month'Valid or else
604 not Day'Valid or else
610 -- Even though the input time zone is UTC (0), the flag Is_Ada_05 will
611 -- ensure that Split picks up the local time zone.
614 Formatting_Operations.Time_Of
624 Use_Day_Secs => True,
633 function Year (Date : Time) return Year_Number is
638 pragma Unreferenced (M, D, S);
640 Split (Date, Y, M, D, S);
644 -- The following packages assume that Time is a signed 64 bit integer
645 -- type, the units are nanoseconds and the origin is the start of Ada
646 -- time (1901-01-01 00:00:00.0 UTC).
648 ---------------------------
649 -- Arithmetic_Operations --
650 ---------------------------
652 package body Arithmetic_Operations is
658 function Add (Date : Time; Days : Long_Integer) return Time is
659 pragma Unsuppress (Overflow_Check);
660 Date_N : constant Time_Rep := Time_Rep (Date);
662 return Time (Date_N + Time_Rep (Days) * Nanos_In_Day);
664 when Constraint_Error =>
675 Days : out Long_Integer;
676 Seconds : out Duration;
677 Leap_Seconds : out Integer)
681 Elapsed_Leaps : Natural;
683 Negate : Boolean := False;
684 Next_Leap_N : Time_Rep;
686 Sub_Secs_Diff : Time_Rep;
689 -- Both input time values are assumed to be in UTC
691 if Left >= Right then
692 Later := Time_Rep (Left);
693 Earlier := Time_Rep (Right);
695 Later := Time_Rep (Right);
696 Earlier := Time_Rep (Left);
700 -- If the target supports leap seconds, process them
703 Cumulative_Leap_Seconds
704 (Earlier, Later, Elapsed_Leaps, Next_Leap_N);
706 if Later >= Next_Leap_N then
707 Elapsed_Leaps := Elapsed_Leaps + 1;
710 -- The target does not support leap seconds
716 -- Sub seconds processing. We add the resulting difference to one
717 -- of the input dates in order to account for any potential rounding
718 -- of the difference in the next step.
720 Sub_Secs_Diff := Later mod Nano - Earlier mod Nano;
721 Earlier := Earlier + Sub_Secs_Diff;
722 Sub_Secs := Duration (Sub_Secs_Diff) / Nano_F;
724 -- Difference processing. This operation should be able to calculate
725 -- the difference between opposite values which are close to the end
726 -- and start of Ada time. To accommodate the large range, we convert
727 -- to seconds. This action may potentially round the two values and
728 -- either add or drop a second. We compensate for this issue in the
732 Time_Dur (Later / Nano - Earlier / Nano) - Time_Dur (Elapsed_Leaps);
734 Days := Long_Integer (Res_Dur / Secs_In_Day);
735 Seconds := Duration (Res_Dur mod Secs_In_Day) + Sub_Secs;
736 Leap_Seconds := Integer (Elapsed_Leaps);
742 if Leap_Seconds /= 0 then
743 Leap_Seconds := -Leap_Seconds;
752 function Subtract (Date : Time; Days : Long_Integer) return Time is
753 pragma Unsuppress (Overflow_Check);
754 Date_N : constant Time_Rep := Time_Rep (Date);
756 return Time (Date_N - Time_Rep (Days) * Nanos_In_Day);
758 when Constraint_Error =>
762 end Arithmetic_Operations;
764 ---------------------------
765 -- Conversion_Operations --
766 ---------------------------
768 package body Conversion_Operations is
774 function To_Ada_Time (Unix_Time : Long_Integer) return Time is
775 pragma Unsuppress (Overflow_Check);
776 Unix_Rep : constant Time_Rep := Time_Rep (Unix_Time) * Nano;
778 return Time (Unix_Rep - Epoch_Offset);
780 when Constraint_Error =>
795 tm_isdst : Integer) return Time
797 pragma Unsuppress (Overflow_Check);
799 Month : Month_Number;
808 Year := Year_Number (1900 + tm_year);
809 Month := Month_Number (1 + tm_mon);
810 Day := Day_Number (tm_day);
812 -- Step 1: Validity checks of input values
814 if not Year'Valid or else not Month'Valid or else not Day'Valid
815 or else tm_hour not in 0 .. 24
816 or else tm_min not in 0 .. 59
817 or else tm_sec not in 0 .. 60
818 or else tm_isdst not in -1 .. 1
823 -- Step 2: Potential leap second
833 -- Step 3: Calculate the time value
837 (Formatting_Operations.Time_Of
841 Day_Secs => 0.0, -- Time is given in h:m:s
845 Sub_Sec => 0.0, -- No precise sub second given
847 Use_Day_Secs => False, -- Time is given in h:m:s
848 Is_Ada_05 => True, -- Force usage of explicit time zone
849 Time_Zone => 0)); -- Place the value in UTC
851 -- Step 4: Daylight Savings Time
854 Result := Result + Time_Rep (3_600) * Nano;
857 return Time (Result);
860 when Constraint_Error =>
869 (tv_sec : Long_Integer;
870 tv_nsec : Long_Integer) return Duration
872 pragma Unsuppress (Overflow_Check);
874 return Duration (tv_sec) + Duration (tv_nsec) / Nano_F;
877 ------------------------
878 -- To_Struct_Timespec --
879 ------------------------
881 procedure To_Struct_Timespec
883 tv_sec : out Long_Integer;
884 tv_nsec : out Long_Integer)
886 pragma Unsuppress (Overflow_Check);
888 Nano_Secs : Duration;
891 -- Seconds extraction, avoid potential rounding errors
894 tv_sec := Long_Integer (Secs);
896 -- Nanoseconds extraction
898 Nano_Secs := D - Duration (tv_sec);
899 tv_nsec := Long_Integer (Nano_Secs * Nano);
900 end To_Struct_Timespec;
906 procedure To_Struct_Tm
908 tm_year : out Integer;
909 tm_mon : out Integer;
910 tm_day : out Integer;
911 tm_hour : out Integer;
912 tm_min : out Integer;
913 tm_sec : out Integer)
915 pragma Unsuppress (Overflow_Check);
917 Month : Month_Number;
919 Day_Secs : Day_Duration;
924 -- Step 1: Split the input time
926 Formatting_Operations.Split
927 (T, Year, Month, tm_day, Day_Secs,
928 tm_hour, tm_min, Second, Sub_Sec, Leap_Sec, True, 0);
930 -- Step 2: Correct the year and month
932 tm_year := Year - 1900;
935 -- Step 3: Handle leap second occurrences
937 tm_sec := (if Leap_Sec then 60 else Second);
944 function To_Unix_Time (Ada_Time : Time) return Long_Integer is
945 pragma Unsuppress (Overflow_Check);
946 Ada_Rep : constant Time_Rep := Time_Rep (Ada_Time);
948 return Long_Integer ((Ada_Rep + Epoch_Offset) / Nano);
950 when Constraint_Error =>
953 end Conversion_Operations;
955 ----------------------
956 -- Delay_Operations --
957 ----------------------
959 package body Delay_Operations is
965 function To_Duration (Date : Time) return Duration is
966 pragma Unsuppress (Overflow_Check);
968 Safe_Ada_High : constant Time_Rep := Ada_High - Epoch_Offset;
969 -- This value represents a "safe" end of time. In order to perform a
970 -- proper conversion to Unix duration, we will have to shift origins
971 -- at one point. For very distant dates, this means an overflow check
972 -- failure. To prevent this, the function returns the "safe" end of
973 -- time (roughly 2219) which is still distant enough.
975 Elapsed_Leaps : Natural;
976 Next_Leap_N : Time_Rep;
980 Res_N := Time_Rep (Date);
982 -- Step 1: If the target supports leap seconds, remove any leap
983 -- seconds elapsed up to the input date.
986 Cumulative_Leap_Seconds
987 (Start_Of_Time, Res_N, Elapsed_Leaps, Next_Leap_N);
989 -- The input time value may fall on a leap second occurrence
991 if Res_N >= Next_Leap_N then
992 Elapsed_Leaps := Elapsed_Leaps + 1;
995 -- The target does not support leap seconds
1001 Res_N := Res_N - Time_Rep (Elapsed_Leaps) * Nano;
1003 -- Step 2: Perform a shift in origins to obtain a Unix equivalent of
1004 -- the input. Guard against very large delay values such as the end
1005 -- of time since the computation will overflow.
1007 Res_N := (if Res_N > Safe_Ada_High then Safe_Ada_High
1008 else Res_N + Epoch_Offset);
1010 return Time_Rep_To_Duration (Res_N);
1013 end Delay_Operations;
1015 ---------------------------
1016 -- Formatting_Operations --
1017 ---------------------------
1019 package body Formatting_Operations is
1025 function Day_Of_Week (Date : Time) return Integer is
1026 Date_N : constant Time_Rep := Time_Rep (Date);
1027 Time_Zone : constant Long_Integer :=
1028 Time_Zones_Operations.UTC_Time_Offset (Date);
1029 Ada_Low_N : Time_Rep;
1030 Day_Count : Long_Integer;
1036 -- As declared, the Ada Epoch is set in UTC. For this calculation to
1037 -- work properly, both the Epoch and the input date must be in the
1038 -- same time zone. The following places the Epoch in the input date's
1041 Ada_Low_N := Ada_Low - Time_Rep (Time_Zone) * Nano;
1043 if Date_N > Ada_Low_N then
1047 High_N := Ada_Low_N;
1051 -- Determine the elapsed seconds since the start of Ada time
1053 Day_Dur := Time_Dur (High_N / Nano - Low_N / Nano);
1055 -- Count the number of days since the start of Ada time. 1901-01-01
1056 -- GMT was a Tuesday.
1058 Day_Count := Long_Integer (Day_Dur / Secs_In_Day) + 1;
1060 return Integer (Day_Count mod 7);
1069 Year : out Year_Number;
1070 Month : out Month_Number;
1071 Day : out Day_Number;
1072 Day_Secs : out Day_Duration;
1074 Minute : out Integer;
1075 Second : out Integer;
1076 Sub_Sec : out Duration;
1077 Leap_Sec : out Boolean;
1078 Is_Ada_05 : Boolean;
1079 Time_Zone : Long_Integer)
1081 -- The following constants represent the number of nanoseconds
1082 -- elapsed since the start of Ada time to and including the non
1083 -- leap centennial years.
1085 Year_2101 : constant Time_Rep := Ada_Low +
1086 Time_Rep (49 * 366 + 151 * 365) * Nanos_In_Day;
1087 Year_2201 : constant Time_Rep := Ada_Low +
1088 Time_Rep (73 * 366 + 227 * 365) * Nanos_In_Day;
1089 Year_2301 : constant Time_Rep := Ada_Low +
1090 Time_Rep (97 * 366 + 303 * 365) * Nanos_In_Day;
1092 Date_Dur : Time_Dur;
1094 Day_Seconds : Natural;
1095 Elapsed_Leaps : Natural;
1096 Four_Year_Segs : Natural;
1097 Hour_Seconds : Natural;
1098 Is_Leap_Year : Boolean;
1099 Next_Leap_N : Time_Rep;
1100 Rem_Years : Natural;
1101 Sub_Sec_N : Time_Rep;
1105 Date_N := Time_Rep (Date);
1107 -- Step 1: Leap seconds processing in UTC
1109 if Leap_Support then
1110 Cumulative_Leap_Seconds
1111 (Start_Of_Time, Date_N, Elapsed_Leaps, Next_Leap_N);
1113 Leap_Sec := Date_N >= Next_Leap_N;
1116 Elapsed_Leaps := Elapsed_Leaps + 1;
1119 -- The target does not support leap seconds
1126 Date_N := Date_N - Time_Rep (Elapsed_Leaps) * Nano;
1128 -- Step 2: Time zone processing. This action converts the input date
1129 -- from GMT to the requested time zone. Applies from Ada 2005 on.
1132 if Time_Zone /= 0 then
1133 Date_N := Date_N + Time_Rep (Time_Zone) * 60 * Nano;
1140 Off : constant Long_Integer :=
1141 Time_Zones_Operations.UTC_Time_Offset (Time (Date_N));
1143 Date_N := Date_N + Time_Rep (Off) * Nano;
1147 -- Step 3: Non-leap centennial year adjustment in local time zone
1149 -- In order for all divisions to work properly and to avoid more
1150 -- complicated arithmetic, we add fake February 29s to dates which
1151 -- occur after a non-leap centennial year.
1153 if Date_N >= Year_2301 then
1154 Date_N := Date_N + Time_Rep (3) * Nanos_In_Day;
1156 elsif Date_N >= Year_2201 then
1157 Date_N := Date_N + Time_Rep (2) * Nanos_In_Day;
1159 elsif Date_N >= Year_2101 then
1160 Date_N := Date_N + Time_Rep (1) * Nanos_In_Day;
1163 -- Step 4: Sub second processing in local time zone
1165 Sub_Sec_N := Date_N mod Nano;
1166 Sub_Sec := Duration (Sub_Sec_N) / Nano_F;
1167 Date_N := Date_N - Sub_Sec_N;
1169 -- Convert Date_N into a time duration value, changing the units
1172 Date_Dur := Time_Dur (Date_N / Nano - Ada_Low / Nano);
1174 -- Step 5: Year processing in local time zone. Determine the number
1175 -- of four year segments since the start of Ada time and the input
1178 Four_Year_Segs := Natural (Date_Dur / Secs_In_Four_Years);
1180 if Four_Year_Segs > 0 then
1181 Date_Dur := Date_Dur - Time_Dur (Four_Year_Segs) *
1185 -- Calculate the remaining non-leap years
1187 Rem_Years := Natural (Date_Dur / Secs_In_Non_Leap_Year);
1189 if Rem_Years > 3 then
1193 Date_Dur := Date_Dur - Time_Dur (Rem_Years) * Secs_In_Non_Leap_Year;
1195 Year := Ada_Min_Year + Natural (4 * Four_Year_Segs + Rem_Years);
1196 Is_Leap_Year := Is_Leap (Year);
1198 -- Step 6: Month and day processing in local time zone
1200 Year_Day := Natural (Date_Dur / Secs_In_Day) + 1;
1204 -- Processing for months after January
1206 if Year_Day > 31 then
1208 Year_Day := Year_Day - 31;
1210 -- Processing for a new month or a leap February
1213 and then (not Is_Leap_Year or else Year_Day > 29)
1216 Year_Day := Year_Day - 28;
1218 if Is_Leap_Year then
1219 Year_Day := Year_Day - 1;
1224 while Year_Day > Days_In_Month (Month) loop
1225 Year_Day := Year_Day - Days_In_Month (Month);
1231 -- Step 7: Hour, minute, second and sub second processing in local
1234 Day := Day_Number (Year_Day);
1235 Day_Seconds := Integer (Date_Dur mod Secs_In_Day);
1236 Day_Secs := Duration (Day_Seconds) + Sub_Sec;
1237 Hour := Day_Seconds / 3_600;
1238 Hour_Seconds := Day_Seconds mod 3_600;
1239 Minute := Hour_Seconds / 60;
1240 Second := Hour_Seconds mod 60;
1248 (Year : Year_Number;
1249 Month : Month_Number;
1251 Day_Secs : Day_Duration;
1256 Leap_Sec : Boolean := False;
1257 Use_Day_Secs : Boolean := False;
1258 Is_Ada_05 : Boolean := False;
1259 Time_Zone : Long_Integer := 0) return Time
1262 Elapsed_Leaps : Natural;
1263 Next_Leap_N : Time_Rep;
1265 Rounded_Res_N : Time_Rep;
1268 -- Step 1: Check whether the day, month and year form a valid date
1270 if Day > Days_In_Month (Month)
1271 and then (Day /= 29 or else Month /= 2 or else not Is_Leap (Year))
1276 -- Start accumulating nanoseconds from the low bound of Ada time
1280 -- Step 2: Year processing and centennial year adjustment. Determine
1281 -- the number of four year segments since the start of Ada time and
1284 Count := (Year - Year_Number'First) / 4;
1286 for Four_Year_Segments in 1 .. Count loop
1287 Res_N := Res_N + Nanos_In_Four_Years;
1290 -- Note that non-leap centennial years are automatically considered
1291 -- leap in the operation above. An adjustment of several days is
1292 -- required to compensate for this.
1295 Res_N := Res_N - Time_Rep (3) * Nanos_In_Day;
1297 elsif Year > 2200 then
1298 Res_N := Res_N - Time_Rep (2) * Nanos_In_Day;
1300 elsif Year > 2100 then
1301 Res_N := Res_N - Time_Rep (1) * Nanos_In_Day;
1304 -- Add the remaining non-leap years
1306 Count := (Year - Year_Number'First) mod 4;
1307 Res_N := Res_N + Time_Rep (Count) * Secs_In_Non_Leap_Year * Nano;
1309 -- Step 3: Day of month processing. Determine the number of days
1310 -- since the start of the current year. Do not add the current
1311 -- day since it has not elapsed yet.
1313 Count := Cumulative_Days_Before_Month (Month) + Day - 1;
1315 -- The input year is leap and we have passed February
1323 Res_N := Res_N + Time_Rep (Count) * Nanos_In_Day;
1325 -- Step 4: Hour, minute, second and sub second processing
1327 if Use_Day_Secs then
1328 Res_N := Res_N + Duration_To_Time_Rep (Day_Secs);
1332 Res_N + Time_Rep (Hour * 3_600 + Minute * 60 + Second) * Nano;
1334 if Sub_Sec = 1.0 then
1335 Res_N := Res_N + Time_Rep (1) * Nano;
1337 Res_N := Res_N + Duration_To_Time_Rep (Sub_Sec);
1341 -- At this point, the generated time value should be withing the
1342 -- bounds of Ada time.
1344 Check_Within_Time_Bounds (Res_N);
1346 -- Step 4: Time zone processing. At this point we have built an
1347 -- arbitrary time value which is not related to any time zone.
1348 -- For simplicity, the time value is normalized to GMT, producing
1349 -- a uniform representation which can be treated by arithmetic
1350 -- operations for instance without any additional corrections.
1353 if Time_Zone /= 0 then
1354 Res_N := Res_N - Time_Rep (Time_Zone) * 60 * Nano;
1361 Current_Off : constant Long_Integer :=
1362 Time_Zones_Operations.UTC_Time_Offset
1364 Current_Res_N : constant Time_Rep :=
1365 Res_N - Time_Rep (Current_Off) * Nano;
1366 Off : constant Long_Integer :=
1367 Time_Zones_Operations.UTC_Time_Offset
1368 (Time (Current_Res_N));
1370 Res_N := Res_N - Time_Rep (Off) * Nano;
1374 -- Step 5: Leap seconds processing in GMT
1376 if Leap_Support then
1377 Cumulative_Leap_Seconds
1378 (Start_Of_Time, Res_N, Elapsed_Leaps, Next_Leap_N);
1380 Res_N := Res_N + Time_Rep (Elapsed_Leaps) * Nano;
1382 -- An Ada 2005 caller requesting an explicit leap second or an
1383 -- Ada 95 caller accounting for an invisible leap second.
1385 if Leap_Sec or else Res_N >= Next_Leap_N then
1386 Res_N := Res_N + Time_Rep (1) * Nano;
1389 -- Leap second validity check
1391 Rounded_Res_N := Res_N - (Res_N mod Nano);
1395 and then Rounded_Res_N /= Next_Leap_N
1401 return Time (Res_N);
1404 end Formatting_Operations;
1406 ---------------------------
1407 -- Time_Zones_Operations --
1408 ---------------------------
1410 package body Time_Zones_Operations is
1412 -- The Unix time bounds in nanoseconds: 1970/1/1 .. 2037/1/1
1414 Unix_Min : constant Time_Rep := Ada_Low +
1415 Time_Rep (17 * 366 + 52 * 365) * Nanos_In_Day;
1417 Unix_Max : constant Time_Rep := Ada_Low +
1418 Time_Rep (34 * 366 + 102 * 365) * Nanos_In_Day +
1419 Time_Rep (Leap_Seconds_Count) * Nano;
1421 -- The following constants denote February 28 during non-leap
1422 -- centennial years, the units are nanoseconds.
1424 T_2100_2_28 : constant Time_Rep := Ada_Low +
1425 (Time_Rep (49 * 366 + 150 * 365 + 59) * Secs_In_Day +
1426 Time_Rep (Leap_Seconds_Count)) * Nano;
1428 T_2200_2_28 : constant Time_Rep := Ada_Low +
1429 (Time_Rep (73 * 366 + 226 * 365 + 59) * Secs_In_Day +
1430 Time_Rep (Leap_Seconds_Count)) * Nano;
1432 T_2300_2_28 : constant Time_Rep := Ada_Low +
1433 (Time_Rep (97 * 366 + 302 * 365 + 59) * Secs_In_Day +
1434 Time_Rep (Leap_Seconds_Count)) * Nano;
1436 -- 56 years (14 leap years + 42 non leap years) in nanoseconds:
1438 Nanos_In_56_Years : constant := (14 * 366 + 42 * 365) * Nanos_In_Day;
1440 subtype long is Long_Integer;
1441 type long_Pointer is access all long;
1444 range -(2 ** (Standard'Address_Size - Integer'(1))) ..
1445 +(2 ** (Standard'Address_Size - Integer'(1)) - 1);
1446 type time_t_Pointer is access all time_t;
1448 procedure localtime_tzoff
1449 (timer : time_t_Pointer;
1450 off : long_Pointer);
1451 pragma Import (C, localtime_tzoff, "__gnat_localtime_tzoff");
1452 -- This is a lightweight wrapper around the system library function
1453 -- localtime_r. Parameter 'off' captures the UTC offset which is either
1454 -- retrieved from the tm struct or calculated from the 'timezone' extern
1455 -- and the tm_isdst flag in the tm struct.
1457 ---------------------
1458 -- UTC_Time_Offset --
1459 ---------------------
1461 function UTC_Time_Offset (Date : Time) return Long_Integer is
1464 Offset : aliased long;
1465 Secs_T : aliased time_t;
1468 Date_N := Time_Rep (Date);
1470 -- Dates which are 56 years apart fall on the same day, day light
1471 -- saving and so on. Non-leap centennial years violate this rule by
1472 -- one day and as a consequence, special adjustment is needed.
1475 (if Date_N <= T_2100_2_28 then 0
1476 elsif Date_N <= T_2200_2_28 then 1
1477 elsif Date_N <= T_2300_2_28 then 2
1480 if Adj_Cent > 0 then
1481 Date_N := Date_N - Time_Rep (Adj_Cent) * Nanos_In_Day;
1484 -- Shift the date within bounds of Unix time
1486 while Date_N < Unix_Min loop
1487 Date_N := Date_N + Nanos_In_56_Years;
1490 while Date_N >= Unix_Max loop
1491 Date_N := Date_N - Nanos_In_56_Years;
1494 -- Perform a shift in origins from Ada to Unix
1496 Date_N := Date_N - Unix_Min;
1498 -- Convert the date into seconds
1500 Secs_T := time_t (Date_N / Nano);
1503 (Secs_T'Unchecked_Access,
1504 Offset'Unchecked_Access);
1507 end UTC_Time_Offset;
1509 end Time_Zones_Operations;
1511 -- Start of elaboration code for Ada.Calendar
1514 System.OS_Primitives.Initialize;