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1 ------------------------------------------------------------------------------
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2 -- --
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3 -- GNAT RUN-TIME COMPONENTS --
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4 -- --
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5 -- A D A . C A L E N D A R --
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6 -- --
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7 -- S p e c --
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8 -- --
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131
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9 -- Copyright (C) 1992-2018, Free Software Foundation, Inc. --
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111
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10 -- --
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11 -- This specification is derived from the Ada Reference Manual for use with --
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12 -- GNAT. The copyright notice above, and the license provisions that follow --
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13 -- apply solely to the contents of the part following the private keyword. --
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14 -- --
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15 -- GNAT is free software; you can redistribute it and/or modify it under --
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16 -- terms of the GNU General Public License as published by the Free Soft- --
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17 -- ware Foundation; either version 3, or (at your option) any later ver- --
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18 -- sion. GNAT is distributed in the hope that it will be useful, but WITH- --
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19 -- OUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY --
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20 -- or FITNESS FOR A PARTICULAR PURPOSE. --
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21 -- --
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22 -- As a special exception under Section 7 of GPL version 3, you are granted --
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23 -- additional permissions described in the GCC Runtime Library Exception, --
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24 -- version 3.1, as published by the Free Software Foundation. --
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25 -- --
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26 -- You should have received a copy of the GNU General Public License and --
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27 -- a copy of the GCC Runtime Library Exception along with this program; --
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28 -- see the files COPYING3 and COPYING.RUNTIME respectively. If not, see --
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29 -- <http://www.gnu.org/licenses/>. --
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30 -- --
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31 -- GNAT was originally developed by the GNAT team at New York University. --
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32 -- Extensive contributions were provided by Ada Core Technologies Inc. --
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33 -- --
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34 ------------------------------------------------------------------------------
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35
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36 package Ada.Calendar with
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37 SPARK_Mode,
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131
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38 Abstract_State => (Clock_Time with Synchronous),
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39 Initializes => Clock_Time
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40 is
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41
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42 type Time is private;
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43
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44 -- Declarations representing limits of allowed local time values. Note that
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45 -- these do NOT constrain the possible stored values of time which may well
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46 -- permit a larger range of times (this is explicitly allowed in Ada 95).
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47
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48 subtype Year_Number is Integer range 1901 .. 2399;
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49 subtype Month_Number is Integer range 1 .. 12;
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50 subtype Day_Number is Integer range 1 .. 31;
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51
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52 -- A Day_Duration value of 86_400.0 designates a new day
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53
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54 subtype Day_Duration is Duration range 0.0 .. 86_400.0;
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55
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56 function Clock return Time with
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57 Volatile_Function,
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58 Global => Clock_Time;
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59 -- The returned time value is the number of nanoseconds since the start
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60 -- of Ada time (1901-01-01 00:00:00.0 UTC). If leap seconds are enabled,
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61 -- the result will contain all elapsed leap seconds since the start of
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62 -- Ada time until now.
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63
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64 function Year (Date : Time) return Year_Number;
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65 function Month (Date : Time) return Month_Number;
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66 function Day (Date : Time) return Day_Number;
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67 function Seconds (Date : Time) return Day_Duration;
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68
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69 procedure Split
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70 (Date : Time;
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71 Year : out Year_Number;
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72 Month : out Month_Number;
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73 Day : out Day_Number;
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74 Seconds : out Day_Duration);
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75 -- Break down a time value into its date components set in the current
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76 -- time zone. If Split is called on a time value created using Ada 2005
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77 -- Time_Of in some arbitrary time zone, the input value will always be
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78 -- interpreted as relative to the local time zone.
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79
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80 function Time_Of
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81 (Year : Year_Number;
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82 Month : Month_Number;
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83 Day : Day_Number;
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84 Seconds : Day_Duration := 0.0) return Time;
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85 -- GNAT Note: Normally when procedure Split is called on a Time value
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86 -- result of a call to function Time_Of, the out parameters of procedure
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87 -- Split are identical to the in parameters of function Time_Of. However,
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88 -- when a non-existent time of day is specified, the values for Seconds
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89 -- may or may not be different. This may happen when Daylight Saving Time
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90 -- (DST) is in effect, on the day when switching to DST, if Seconds
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91 -- specifies a time of day in the hour that does not exist. For example,
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92 -- in New York:
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93 --
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94 -- Time_Of (Year => 1998, Month => 4, Day => 5, Seconds => 10740.0)
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95 --
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96 -- will return a Time value T. If Split is called on T, the resulting
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97 -- Seconds may be 14340.0 (3:59:00) instead of 10740.0 (2:59:00 being
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98 -- a time that not exist).
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99
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100 function "+" (Left : Time; Right : Duration) return Time;
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101 function "+" (Left : Duration; Right : Time) return Time;
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102 function "-" (Left : Time; Right : Duration) return Time;
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103 function "-" (Left : Time; Right : Time) return Duration;
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104 -- The first three functions will raise Time_Error if the resulting time
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105 -- value is less than the start of Ada time in UTC or greater than the
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106 -- end of Ada time in UTC. The last function will raise Time_Error if the
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107 -- resulting difference cannot fit into a duration value.
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108
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109 function "<" (Left, Right : Time) return Boolean;
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110 function "<=" (Left, Right : Time) return Boolean;
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111 function ">" (Left, Right : Time) return Boolean;
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112 function ">=" (Left, Right : Time) return Boolean;
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113
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114 Time_Error : exception;
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115
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116 private
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117 -- Mark the private part as SPARK_Mode Off to avoid accounting for variable
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118 -- Invalid_Time_Zone_Offset in abstract state.
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119
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120 pragma SPARK_Mode (Off);
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121
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122 pragma Inline (Clock);
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123
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124 pragma Inline (Year);
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125 pragma Inline (Month);
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126 pragma Inline (Day);
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127
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128 pragma Inline ("+");
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129 pragma Inline ("-");
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130
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131 pragma Inline ("<");
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132 pragma Inline ("<=");
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133 pragma Inline (">");
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134 pragma Inline (">=");
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135
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136 -- The units used in this version of Ada.Calendar are nanoseconds. The
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137 -- following constants provide values used in conversions of seconds or
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138 -- days to the underlying units.
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139
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140 Nano : constant := 1_000_000_000;
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141 Nano_F : constant := 1_000_000_000.0;
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142 Nanos_In_Day : constant := 86_400_000_000_000;
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143 Secs_In_Day : constant := 86_400;
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144
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145 ----------------------------
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146 -- Implementation of Time --
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147 ----------------------------
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148
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149 -- Time is represented as a signed 64 bit integer count of nanoseconds
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150 -- since the start of Ada time (1901-01-01 00:00:00.0 UTC). Time values
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151 -- produced by Time_Of are internally normalized to UTC regardless of their
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152 -- local time zone. This representation ensures correct handling of leap
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153 -- seconds as well as performing arithmetic. In Ada 95, Split and Time_Of
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154 -- will treat a time value as being in the local time zone, in Ada 2005,
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155 -- Split and Time_Of will treat a time value as being in the designated
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156 -- time zone by the formal parameter or in UTC by default. The size of the
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157 -- type is large enough to cover the Ada 2005 range of time (1901-01-01
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158 -- 00:00:00.0 UTC - 2399-12-31-23:59:59.999999999 UTC).
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159
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160 ------------------
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161 -- Leap Seconds --
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162 ------------------
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163
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164 -- Due to Earth's slowdown, the astronomical time is not as precise as the
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165 -- International Atomic Time. To compensate for this inaccuracy, a single
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166 -- leap second is added after the last day of June or December. The count
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167 -- of seconds during those occurrences becomes:
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168
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169 -- ... 58, 59, leap second 60, 0, 1, 2 ...
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170
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171 -- Unlike leap days, leap seconds occur simultaneously around the world.
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172 -- In other words, if a leap second occurs at 23:59:60 UTC, it also occurs
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173 -- on 18:59:60 -5 the same day or 2:59:60 +2 on the next day.
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174
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175 -- Leap seconds do not follow a formula. The International Earth Rotation
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176 -- and Reference System Service decides when to add one. Leap seconds are
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177 -- included in the representation of time in Ada 95 mode. As a result,
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178 -- the following two time values will differ by two seconds:
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179
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180 -- 1972-06-30 23:59:59.0
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181 -- 1972-07-01 00:00:00.0
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182
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183 -- When a new leap second is introduced, the following steps must be
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184 -- carried out:
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185
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186 -- 1) Increment Leap_Seconds_Count in a-calend.adb by one
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187 -- 2) Increment LS_Count in xleaps.adb by one
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188 -- 3) Add the new date to the aggregate of array LS_Dates in
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189 -- xleaps.adb
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190 -- 4) Compile and execute xleaps
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191 -- 5) Replace the values of Leap_Second_Times in a-calend.adb with the
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192 -- aggregate generated by xleaps
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193
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194 -- The algorithms that build the actual leap second values and discover
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195 -- how many leap seconds have occurred between two dates do not need any
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196 -- modification.
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197
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198 ------------------------------
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199 -- Non-leap Centennial Years --
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200 ------------------------------
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201
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202 -- Over the range of Ada time, centennial years 2100, 2200 and 2300 are
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203 -- non-leap. As a consequence, seven non-leap years occur over the period
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204 -- of year - 4 to year + 4. Internally, routines Split and Time_Of add or
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205 -- subtract a "fake" February 29 to facilitate the arithmetic involved.
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206
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207 ------------------------
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208 -- Local Declarations --
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209 ------------------------
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210
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211 type Time_Rep is new Long_Long_Integer;
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212 type Time is new Time_Rep;
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213 -- The underlying type of Time has been chosen to be a 64 bit signed
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214 -- integer number since it allows for easier processing of sub-seconds
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215 -- and arithmetic. We use Long_Long_Integer to allow this unit to compile
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216 -- when using custom target configuration files where the max integer is
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217 -- 32 bits. This is useful for static analysis tools such as SPARK or
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218 -- CodePeer.
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219 --
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220 -- Note: the reason we have two separate types here is to avoid problems
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221 -- with overloading ambiguities in the body if we tried to use Time as an
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222 -- internal computational type.
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223
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224 function Epoch_Offset return Time_Rep;
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225 pragma Inline (Epoch_Offset);
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226 -- Return the difference between 2150-1-1 UTC and 1970-1-1 UTC expressed in
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227 -- nanoseconds. Note that year 2100 is non-leap.
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228
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229 Days_In_Month : constant array (Month_Number) of Day_Number :=
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230 (31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31);
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231 -- Days in month for non-leap year, leap year case is adjusted in code
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232
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233 Invalid_Time_Zone_Offset : Long_Integer;
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234 pragma Import (C, Invalid_Time_Zone_Offset, "__gnat_invalid_tzoff");
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235
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236 function Is_Leap (Year : Year_Number) return Boolean;
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237 -- Determine whether a given year is leap
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238
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239 ----------------------------------------------------------
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240 -- Target-Independent Interface to Children of Calendar --
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241 ----------------------------------------------------------
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242
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243 -- The following packages provide a target-independent interface to the
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244 -- children of Calendar - Arithmetic, Conversions, Delays, Formatting and
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245 -- Time_Zones.
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246
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247 ---------------------------
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248 -- Arithmetic_Operations --
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249 ---------------------------
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250
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251 package Arithmetic_Operations is
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252
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253 function Add (Date : Time; Days : Long_Integer) return Time;
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254 -- Add a certain number of days to a time value
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255
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256 procedure Difference
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257 (Left : Time;
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258 Right : Time;
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259 Days : out Long_Integer;
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260 Seconds : out Duration;
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261 Leap_Seconds : out Integer);
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262 -- Calculate the difference between two time values in terms of days,
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263 -- seconds and leap seconds elapsed. The leap seconds are not included
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264 -- in the seconds returned. If Left is greater than Right, the returned
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265 -- values are positive, negative otherwise.
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266
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267 function Subtract (Date : Time; Days : Long_Integer) return Time;
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268 -- Subtract a certain number of days from a time value
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269
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270 end Arithmetic_Operations;
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271
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272 ---------------------------
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273 -- Conversion_Operations --
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274 ---------------------------
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275
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276 package Conversion_Operations is
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277
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278 function To_Ada_Time (Unix_Time : Long_Integer) return Time;
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279 -- Unix to Ada Epoch conversion
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280
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281 function To_Ada_Time
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282 (tm_year : Integer;
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283 tm_mon : Integer;
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284 tm_day : Integer;
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285 tm_hour : Integer;
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286 tm_min : Integer;
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287 tm_sec : Integer;
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288 tm_isdst : Integer) return Time;
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289 -- Struct tm to Ada Epoch conversion
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290
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291 function To_Duration
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292 (tv_sec : Long_Integer;
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293 tv_nsec : Long_Integer) return Duration;
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294 -- Struct timespec to Duration conversion
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295
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296 procedure To_Struct_Timespec
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297 (D : Duration;
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298 tv_sec : out Long_Integer;
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299 tv_nsec : out Long_Integer);
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300 -- Duration to struct timespec conversion
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301
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302 procedure To_Struct_Tm
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303 (T : Time;
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304 tm_year : out Integer;
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305 tm_mon : out Integer;
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306 tm_day : out Integer;
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307 tm_hour : out Integer;
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308 tm_min : out Integer;
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309 tm_sec : out Integer);
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310 -- Time to struct tm conversion
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311
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312 function To_Unix_Time (Ada_Time : Time) return Long_Integer;
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313 -- Ada to Unix Epoch conversion
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314
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315 end Conversion_Operations;
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316
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317 ----------------------
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318 -- Delay_Operations --
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319 ----------------------
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320
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321 package Delay_Operations is
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322
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323 function To_Duration (Date : Time) return Duration;
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324 -- Given a time value in nanoseconds since 1901, convert it into a
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325 -- duration value giving the number of nanoseconds since the Unix Epoch.
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326
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327 end Delay_Operations;
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328
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329 ---------------------------
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330 -- Formatting_Operations --
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331 ---------------------------
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332
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333 package Formatting_Operations is
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334
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335 function Day_Of_Week (Date : Time) return Integer;
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336 -- Determine which day of week Date falls on. The returned values are
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337 -- within the range of 0 .. 6 (Monday .. Sunday).
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338
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339 procedure Split
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340 (Date : Time;
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341 Year : out Year_Number;
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342 Month : out Month_Number;
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343 Day : out Day_Number;
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344 Day_Secs : out Day_Duration;
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345 Hour : out Integer;
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346 Minute : out Integer;
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347 Second : out Integer;
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348 Sub_Sec : out Duration;
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349 Leap_Sec : out Boolean;
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350 Use_TZ : Boolean;
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351 Is_Historic : Boolean;
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352 Time_Zone : Long_Integer);
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353 pragma Export (Ada, Split, "__gnat_split");
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354 -- Split a time value into its components. If flag Is_Historic is set,
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355 -- this routine would try to use to the best of the OS's abilities the
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356 -- time zone offset that was or will be in effect on Date. Set Use_TZ
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357 -- to use the local time zone (the value in Time_Zone is ignored) when
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358 -- splitting a time value.
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359
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360 function Time_Of
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361 (Year : Year_Number;
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362 Month : Month_Number;
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363 Day : Day_Number;
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364 Day_Secs : Day_Duration;
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365 Hour : Integer;
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366 Minute : Integer;
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367 Second : Integer;
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368 Sub_Sec : Duration;
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369 Leap_Sec : Boolean;
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370 Use_Day_Secs : Boolean;
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371 Use_TZ : Boolean;
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372 Is_Historic : Boolean;
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373 Time_Zone : Long_Integer) return Time;
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374 pragma Export (Ada, Time_Of, "__gnat_time_of");
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375 -- Given all the components of a date, return the corresponding time
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376 -- value. Set Use_Day_Secs to use the value in Day_Secs, otherwise the
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377 -- day duration will be calculated from Hour, Minute, Second and Sub_
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378 -- Sec. If flag Is_Historic is set, this routine would try to use to the
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379 -- best of the OS's abilities the time zone offset that was or will be
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380 -- in effect on the input date. Set Use_TZ to use the local time zone
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381 -- (the value in formal Time_Zone is ignored) when building a time value
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382 -- and to verify the validity of a requested leap second.
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383
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384 end Formatting_Operations;
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385
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386 ---------------------------
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387 -- Time_Zones_Operations --
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388 ---------------------------
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389
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390 package Time_Zones_Operations is
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391
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392 function UTC_Time_Offset (Date : Time) return Long_Integer;
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393 -- Return (in seconds) the difference between the local time zone and
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394 -- UTC time at a specific historic date.
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395
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396 end Time_Zones_Operations;
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397
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398 end Ada.Calendar;
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