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+%
+% (c) The GRASP/AQUA Project, Glasgow University, 1995
+%
+\section[LibTime]{Haskell 1.3 Time of Day Library}
+
+The {\em LibTime} library provides the functionality of "time.h",
+adapted to the Haskell environment. It includes timezone information,
+as in System V, and follows RFC 1129 in its use of Coordinated
+Universal Time (UTC).
+
+\begin{code}
+module LibTime (
+ CalendarTime(..),
+ ClockTime,
+ TimeDiff(..),
+ addToClockTime,
+ diffClockTimes,
+ getClockTime,
+ toCalendarTime,
+ toUTCTime,
+ toClockTime
+ ) where
+
+import PreludeIOError
+import PreludeGlaST
+import PS
+
+\end{code}
+
+$ClockTime$ is an abstract type, used for the internal clock time.
+Clock times may be compared, converted to strings, or converted to an
+external calendar time $CalendarTime$.
+
+\begin{code}
+data ClockTime = TOD Integer Integer
+ deriving (Eq, Ord)
+\end{code}
+
+When a $ClockTime$ is shown, it is converted to a string of the form
+$"Mon Nov 28 21:45:41 GMT 1994"$.
+
+For now, we are restricted to roughly:
+Fri Dec 13 20:45:52 1901 through Tue Jan 19 03:14:07 2038, because
+we use the C library routines based on 32 bit integers.
+
+\begin{code}
+instance Text ClockTime where
+ showsPrec p (TOD sec@(J# a# s# d#) nsec) =
+ showString (unsafePerformPrimIO (
+ _ccall_ showTime (I# s#) (_ByteArray (error "ClockTime.show") d#)
+ `thenPrimIO` \ str ->
+ _ccall_ strlen str `thenPrimIO` \ len ->
+ _packCBytesST len str `thenStrictlyST` \ ps ->
+ returnPrimIO (_unpackPS ps)))
+\end{code}
+
+
+$CalendarTime$ is a user-readable and manipulable
+representation of the internal $ClockTime$ type. The
+numeric fields have the following ranges.
+
+\begin{verbatim}
+Value Range Comments
+----- ----- --------
+
+year -maxInt .. maxInt [Pre-Gregorian dates are inaccurate]
+mon 0 .. 11 [Jan = 0, Dec = 11]
+day 1 .. 31
+hour 0 .. 23
+min 0 .. 59
+sec 0 .. 61 [Allows for two leap seconds]
+picosec 0 .. (10^12)-1 [This could be over-precise?]
+wday 0 .. 6 [Sunday = 0, Saturday = 6]
+yday 0 .. 365 [364 in non-Leap years]
+tz -43200 .. 43200 [Variation from UTC in seconds]
+\end{verbatim}
+
+The {\em tzname} field is the name of the time zone. The {\em isdst}
+field indicates whether Daylight Savings Time would be in effect.
+
+\begin{code}
+-- year mon day hour min sec picosec wday yday tzname tz isdst
+data CalendarTime =
+ CalendarTime Int Int Int Int Int Int Integer Int Int String Int Bool
+\end{code}
+
+The $TimeDiff$ type records the difference between two clock times in
+a user-readable way.
+
+\begin{code}
+-- year mon day hour min sec picosec
+data TimeDiff = TimeDiff Int Int Int Int Int Int Integer
+ deriving (Eq,Ord)
+\end{code}
+
+$getClockTime$ returns the current time in its internal representation.
+
+\begin{code}
+getClockTime :: IO ClockTime
+getClockTime =
+ malloc1 `thenStrictlyST` \ i1 ->
+ malloc1 `thenStrictlyST` \ i2 ->
+ _ccall_ getClockTime i1 i2 `thenPrimIO` \ rc ->
+ if rc == 0 then
+ cvtUnsigned i1 `thenStrictlyST` \ sec ->
+ cvtUnsigned i2 `thenStrictlyST` \ nsec ->
+ return (TOD sec (nsec * 1000))
+ else
+ _constructError `thenPrimIO` \ ioError ->
+ failWith ioError
+ where
+ malloc1 (S# s#) =
+ case newIntArray# 1# s# of
+ StateAndMutableByteArray# s2# barr# -> (_MutableByteArray bot barr#, S# s2#)
+ bot = error "getClockTime"
+
+ -- The C routine fills in an unsigned word. We don't have `unsigned2Integer#,'
+ -- so we freeze the data bits and use them for an MP_INT structure. Note that
+ -- zero is still handled specially, although (J# 1# 1# (ptr to 0#)) is probably
+ -- acceptable to gmp.
+
+ cvtUnsigned (_MutableByteArray _ arr#) (S# s#) =
+ case readIntArray# arr# 0# s# of
+ StateAndInt# s2# r# ->
+ if r# ==# 0# then
+ (0, S# s2#)
+ else
+ case unsafeFreezeByteArray# arr# s2# of
+ StateAndByteArray# s3# frozen# -> (J# 1# 1# frozen#, S# s3#)
+
+\end{code}
+
+$addToClockTime$ {\em d} {\em t} adds a time difference {\em d} and a
+clock time {\em t} to yield a new clock time. The difference {\em d}
+may be either positive or negative. $diffClockTimes$ {\em t1} {\em
+t2} returns the difference between two clock times {\em t1} and {\em
+t2} as a $TimeDiff$.
+
+
+\begin{code}
+addToClockTime :: TimeDiff -> ClockTime -> ClockTime
+addToClockTime _ _ = error "addToClockTime unimplemented"
+
+diffClockTimes :: ClockTime -> ClockTime -> TimeDiff
+diffClockTimes _ _ = error "diffClockTimes unimplemented"
+\end{code}
+
+$toCalendarTime$ {\em t} converts {\em t} to a local time, modified by
+the current timezone and daylight savings time settings. $toUTCTime$
+{\em t} converts {\em t} into UTC time. $toClockTime$ {\em l}
+converts {\em l} into the corresponding internal $ClockTime$. The
+{\em wday}, {\em yday}, {\em tzname}, and {\em isdst} fields are
+ignored.
+
+\begin{code}
+toCalendarTime :: ClockTime -> CalendarTime
+toCalendarTime (TOD sec@(J# a# s# d#) psec) = unsafePerformPrimIO (
+ _ccall_ toLocalTime (I# s#) (_ByteArray (error "toCalendarTime") d#)
+ `thenPrimIO` \ tm ->
+ if tm == (``NULL''::_Addr) then
+ error "toCalendarTime{LibTime}: out of range"
+ else
+ _casm_ ``%r = ((struct tm *)%0)->tm_sec;'' tm
+ `thenPrimIO` \ sec ->
+ _casm_ ``%r = ((struct tm *)%0)->tm_min;'' tm
+ `thenPrimIO` \ min ->
+ _casm_ ``%r = ((struct tm *)%0)->tm_hour;'' tm
+ `thenPrimIO` \ hour ->
+ _casm_ ``%r = ((struct tm *)%0)->tm_mday;'' tm
+ `thenPrimIO` \ mday ->
+ _casm_ ``%r = ((struct tm *)%0)->tm_mon;'' tm
+ `thenPrimIO` \ mon ->
+ _casm_ ``%r = ((struct tm *)%0)->tm_year;'' tm
+ `thenPrimIO` \ year ->
+ _casm_ ``%r = ((struct tm *)%0)->tm_wday;'' tm
+ `thenPrimIO` \ wday ->
+ _casm_ ``%r = ((struct tm *)%0)->tm_yday;'' tm
+ `thenPrimIO` \ yday ->
+ _casm_ ``%r = ((struct tm *)%0)->tm_isdst;'' tm
+ `thenPrimIO` \ isdst ->
+ _ccall_ ZONE tm `thenPrimIO` \ zone ->
+ _ccall_ GMTOFF tm `thenPrimIO` \ tz ->
+ _ccall_ strlen zone `thenPrimIO` \ len ->
+ _packCBytesST len zone `thenStrictlyST` \ tzname ->
+ returnPrimIO (CalendarTime (1900+year) mon mday hour min sec psec
+ wday yday (_unpackPS tzname) tz (isdst /= 0))
+ )
+
+toUTCTime :: ClockTime -> CalendarTime
+toUTCTime (TOD sec@(J# a# s# d#) psec) = unsafePerformPrimIO (
+ _ccall_ toUTCTime (I# s#) (_ByteArray (error "toCalendarTime") d#)
+ `thenPrimIO` \ tm ->
+ if tm == (``NULL''::_Addr) then
+ error "toUTCTime{LibTime}: out of range"
+ else
+ _casm_ ``%r = ((struct tm *)%0)->tm_sec;'' tm
+ `thenPrimIO` \ sec ->
+ _casm_ ``%r = ((struct tm *)%0)->tm_min;'' tm
+ `thenPrimIO` \ min ->
+ _casm_ ``%r = ((struct tm *)%0)->tm_hour;'' tm
+ `thenPrimIO` \ hour ->
+ _casm_ ``%r = ((struct tm *)%0)->tm_mday;'' tm
+ `thenPrimIO` \ mday ->
+ _casm_ ``%r = ((struct tm *)%0)->tm_mon;'' tm
+ `thenPrimIO` \ mon ->
+ _casm_ ``%r = ((struct tm *)%0)->tm_year;'' tm
+ `thenPrimIO` \ year ->
+ _casm_ ``%r = ((struct tm *)%0)->tm_wday;'' tm
+ `thenPrimIO` \ wday ->
+ _casm_ ``%r = ((struct tm *)%0)->tm_yday;'' tm
+ `thenPrimIO` \ yday ->
+ returnPrimIO (CalendarTime (1900+year) mon mday hour min sec psec
+ wday yday "UTC" 0 False)
+ )
+
+toClockTime :: CalendarTime -> ClockTime
+toClockTime (CalendarTime year mon mday hour min sec psec wday yday tzname tz isdst) =
+ if psec < 0 || psec > 999999999999 then
+ error "toClockTime{LibTime}: picoseconds out of range"
+ else if tz < -43200 || tz > 43200 then
+ error "toClockTime{LibTime}: timezone offset out of range"
+ else
+ unsafePerformPrimIO (
+ _ccall_ toClockSec year mon mday hour min sec tz
+ `thenPrimIO` \ ptr@(A# ptr#) ->
+ if ptr /= ``NULL'' then
+ returnPrimIO (TOD (int2Integer# (indexIntOffAddr# ptr# 0#)) psec)
+ else
+ error "toClockTime{LibTime}: can't perform conversion"
+ )
+\end{code}
+
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