Date Functions

Date Functions

To ease date-related calculations, the utility library has some functions to convert a date, specified in a ClockData structure, in the number of seconds since 00:00:00 01-Jan-78 and vice versa.

To indicate the date, the ClockData structure (in <utility/date.h>) is used.

struct ClockData
{
    UWORD sec;     /* seconds (0 - 59) */
    UWORD min;     /* minutes (0 - 59) */
    UWORD hour;    /* hour (0 - 23) */
    UWORD mday;    /* day of the month (1 - 31) */
    UWORD month;   /* month of the year (1 - 12) */
    UWORD year;    /* 1978 - */
    UWORD wday;    /* day of the week (0 - 6, where 0 is Sunday) */
};

The following functions are available to operate on ClockData:

Utility Library Date Functions

Amiga2Date()	Calculate the date from the specified timestamp (in seconds).
CheckDate()	Check the legality of a date.
Date2Amiga()	Calculate the timestamp from the specified date.

Amiga2Date() takes a number of seconds from 01-Jan-78 as argument and fills in the supplied ClockData structure with the date and time.

CheckDate() checks if the supplied ClockData structure is valid, and returns the number of seconds from 01-Jan-78 if it is. Note that this function currently does not take the supplied day of the week in account.

Date2Amiga() takes a ClockData structure as argument and returns the number of seconds since 01-Jan-78. The supplied ClockData structure must be valid, since no checking is done.

The following example shows various uses of the utility library date functions.

// a2d.c
#include <exec/types.h>
#include <exec/memory.h>
#include <dos/datetime.h>
#include <devices/timer.h>
 
// Note these three libraries are opened by newlib startup code.
#include <proto/exec.h>
#include <proto/dos.h>
#include <proto/utility.h>
 
#include <proto/timer.h>
 
struct TimerIFace *ITimer = NULL;
 
int main()
{
  struct timerequest *tr = IExec->AllocSysObjectTags(ASOT_IOREQUEST,
    ASOIOR_Size, sizeof(struct TimeRequest),
    ASOIOR_ReplyPort, NULL,
    TAG_END);
 
  if (tr != NULL)
  {
    if (!(IExec->OpenDevice("timer.device", UNIT_VBLANK, (struct IORequest *)tr, 0) ))
    {
      struct Library *TimerBase = tr->tr_node.io_Device;
      ITimer = (struct TimerIFace*)IExec->GetInterface(TimerBase, "main", 1, NULL);
 
      if (ITimer != NULL)
      {
        struct TimeVal tv;
        ITimer->GetSysTime(&tv);
 
        IDOS->Printf("GetSysTime():\t%d %d\n", tv.Seconds, tv.Microseconds);
 
        struct ClockData clockdata;
        IUtility->Amiga2Date(tv.Seconds, &clockdata);
 
        IDOS->Printf("Amiga2Date():  sec %d min %d hour %d\n",
          clockdata.sec, clockdata.min, clockdata.hour);
 
        IDOS->Printf("               mday %d month %d year %d wday %d\n",
          clockdata.mday, clockdata.month, clockdata.year, clockdata.wday);
 
        int32 seconds = IUtility->CheckDate(&clockdata);
 
        IDOS->Printf("CheckDate():\t%ld\n", seconds);
 
        seconds = IUtility->Date2Amiga(&clockdata);
 
        IDOS->Printf("Date2Amiga():\t%ld\n", seconds);
 
        IEXec->DropInterface((struct Interface*)ITimer);
      }
 
      IExec->CloseDevice((struct IORequest *)tr);
    }
 
    IExec->FreeSysObject(ASOT_IOREQUEST, tr);
  }
 
  return RETURN_OK;
}