|
HP OpenVMS Systemsask the wizard |
|
The Question is: I need the inverse function for LIB$DAY(). I have been trying various combinations of LIB$CVT_TO_INTERNAL_TIME (and FROM) and trying to add a delta time. I seem to be able to store DELTA_DAYS in internal format but when I use LIB$ADD_TIMES to add the delt a time to today's date to go back or forth a few days, internal day number doesn't change. If I had the inverse of LIB$DAY my problem would be trivial. Thanks, DGH The Answer is :
The terms date and time will here be used largely interchangeably.
The LIB$CVT_FROM_INTERNAL_TIME call is designed to pick apart the
binary format time, while LIB$CVT_TO_INTERNAL_TIME is designed
to create the binary value. LIB$DAY returns the number of days since
the base date, or since the specified quadword-format time.
The particular question -- the particular manipulation of time you
wish to conduct -- is not entirely clear to the OpenVMS Wizard.
Though you wish the inverse of lib$day -- to convert the days since
base date into a quadword -- you then discuss moving a couple of
days forward or back from the current date.
The binary equivalent of an absolute date is always a positive value,
while a binary delta time is always stored as a negative value. (The
various system service and RTL calls that manipulate the quadword date
format regularly utilize this fact.)
As a start, please see the chapter on time in the Programming Concepts
Manual, and please see the attached example:
#include <descrip.h>
#include <lib$routines.h>
#include <ssdef.h>
#include <starlet.h>
#include <stdio.h>
#include <stsdef.h>
#define MAXASCTIMLEN 23
#define MAXVECTIMLEN 7
main()
{
int RetStat;
$DESCRIPTOR( TimeTodayAscii, "TODAY");
$DESCRIPTOR( TimeSourceAscii, "01-JAN-1995 00:00:01.00");
$DESCRIPTOR( DeltaTimeSourceAscii, "1 00:00:00");
char TimeSourceBinary[] =
{ 0x080, 0x0F5, 0x020, 0x000, 0x000, 0x000, 0x000, 0x000};
struct dsc$descriptor FormattedTimeDesc;
char FormattedTimeBuffer[MAXASCTIMLEN];
unsigned char *TimeBinaryPtr;
int TimeBinaryQW[2];
int TodayBinaryQW[2];
int DeltaTimeBinaryQW[2];
int NewTimeBinaryQW[2];
int DaysSinceBaseDate;
unsigned short int VecTim[MAXVECTIMLEN];
int i;
/*
// example 1:
// Convert time from binary to ASCII.
*/
FormattedTimeDesc.dsc$w_length = MAXASCTIMLEN;
FormattedTimeDesc.dsc$b_dtype = DSC$K_DTYPE_T;
FormattedTimeDesc.dsc$b_class = DSC$K_CLASS_S;
FormattedTimeDesc.dsc$a_pointer = FormattedTimeBuffer;
RetStat = sys$asctim( 0, &FormattedTimeDesc, TimeSourceBinary, 0 );
if (!$VMS_STATUS_SUCCESS( RetStat ))
return RetStat;
RetStat = lib$put_output( &FormattedTimeDesc );
if (!$VMS_STATUS_SUCCESS( RetStat ))
return RetStat;
/*
// example 2:
// Convert time from ASCII to binary and back to ASCII.
*/
RetStat = sys$bintim( &TimeSourceAscii, TimeBinaryQW );
if (!$VMS_STATUS_SUCCESS( RetStat ))
return RetStat;
RetStat = sys$asctim( 0, &FormattedTimeDesc, TimeBinaryQW, 0 );
if (!$VMS_STATUS_SUCCESS( RetStat ))
return RetStat;
TimeBinaryPtr = (unsigned char *) TimeBinaryQW;
printf("0x0%2.2x 0x0%2.2x 0x0%2.2x 0x0%2.2x 0x0%2.2x 0x0%2.2x 0x0%2.2x 0x0%2.2x\n",
TimeBinaryPtr[0], TimeBinaryPtr[1],
TimeBinaryPtr[2], TimeBinaryPtr[3],
TimeBinaryPtr[4], TimeBinaryPtr[5],
TimeBinaryPtr[6], TimeBinaryPtr[7] );
RetStat = lib$put_output( &FormattedTimeDesc );
if (!$VMS_STATUS_SUCCESS( RetStat ))
return RetStat;
/*
// Example 3:
// Display the number of days between the base date and the
// specified binary time...
*/
RetStat = lib$day( &DaysSinceBaseDate, TimeBinaryQW, NULL );
if (!$VMS_STATUS_SUCCESS( RetStat ))
return RetStat;
printf("Days Since Base Date for %*.*s: %d\n",
TimeSourceAscii.dsc$w_length, TimeSourceAscii.dsc$w_length,
TimeSourceAscii.dsc$a_pointer, DaysSinceBaseDate );
/*
// Example 4:
// Display the number of days since the base date for today...
// Add some times together and then display the number of days...
// Subtract some times and then display the number of days...
*/
RetStat = sys$gettim( TodayBinaryQW );
if (!$VMS_STATUS_SUCCESS( RetStat ))
return RetStat;
RetStat = lib$day( &DaysSinceBaseDate, TodayBinaryQW, NULL );
if (!$VMS_STATUS_SUCCESS( RetStat ))
return RetStat;
printf("Days Since Base Date Today: %d\n", DaysSinceBaseDate );
RetStat = sys$bintim( &DeltaTimeSourceAscii, DeltaTimeBinaryQW );
if (!$VMS_STATUS_SUCCESS( RetStat ))
return RetStat;
RetStat = lib$add_times( TodayBinaryQW, DeltaTimeBinaryQW,
NewTimeBinaryQW );
if (!$VMS_STATUS_SUCCESS( RetStat ))
return RetStat;
RetStat = lib$day( &DaysSinceBaseDate, NewTimeBinaryQW, NULL );
if (!$VMS_STATUS_SUCCESS( RetStat ))
return RetStat;
printf("Days Since Base Date Tomorrow: %d\n", DaysSinceBaseDate );
RetStat = lib$sub_times( TodayBinaryQW, DeltaTimeBinaryQW,
NewTimeBinaryQW );
if (!$VMS_STATUS_SUCCESS( RetStat ))
return RetStat;
RetStat = lib$day( &DaysSinceBaseDate, NewTimeBinaryQW, NULL );
if (!$VMS_STATUS_SUCCESS( RetStat ))
return RetStat;
printf("Days Since Base Date Yesterday: %d\n", DaysSinceBaseDate );
/*
// Example 5:
// Convert from a quadword into a time vector...
// Then reconstitute the quadword from the vector...
*/
RetStat = sys$numtim( VecTim, TimeBinaryQW );
if (!$VMS_STATUS_SUCCESS( RetStat ))
return RetStat;
for (i = 0; i < MAXVECTIMLEN; i++ )
printf("VecTim[%d] = %d\n", i, VecTim[i] );
RetStat = lib$cvt_vectim( VecTim, NewTimeBinaryQW );
if (!$VMS_STATUS_SUCCESS( RetStat ))
return RetStat;
RetStat = sys$asctim( 0, &FormattedTimeDesc, NewTimeBinaryQW, 0 );
if (!$VMS_STATUS_SUCCESS( RetStat ))
return RetStat;
RetStat = lib$put_output( &FormattedTimeDesc );
if (!$VMS_STATUS_SUCCESS( RetStat ))
return RetStat;
return SS$_NORMAL;
}
|