utc_cmpintervaltime(3dts)

Synopsis

#include <dce/utc.h>

int utc_cmpintervaltime(
enum utc_cmptype *relation,
utc_t *utc1,
utc_t *utc2);

Parameters

Input

utc1
Binary timestamp or relative binary timestamp. Use NULL if you want this routine to use the current time for this parameter.

utc2
Binary timestamp or relative binary timestamp. Use NULL if you want this routine to use the current time for this parameter.

Output

relation
Receives the result of the comparison of utc1:utc2, where the result is an enumerated type with one of the following values:

· utc_equalTo

· utc_lessThan

· utc_greaterThan

· utc_indeterminate

Description
The utc_cmpintervaltime( ) routine compares two binary timestamps and returns a flag indicating that the first time is greater than, less than, equal to, or overlapping with the second time. Two times overlap if the intervals (time inaccuracy, time + inaccuracy) of the two times intersect.

The input binary timestamps express two absolute or two relative times. Do not compare relative binary timestamps to absolute binary timestamps. If you do, no meaningful results and no errors are returned.

The following routine does a temporal ordering of the time intervals.

utc1 is utc_lessThan utc2 iff
utc1.time + utc1.inacc < utc2.time - utc2.inacc
utc1 is utc_greaterThan utc2 iff
utc1.time - utc1.inacc > utc2.time + utc2.inacc
utc1 utc_equalTo utc2 iff
utc1.time == utc2.time and
utc1.inacc == 0 and
utc2.inacc == 0

utc1 is utc_indeterminate with respect to utc2 if the intervals overlap.

Return Values
~0 Indicates that the routine executed successfully.

1 Indicates an invalid time argument.

Examples
The following example checks to see if the current time is definitely after 13:00 local time.

struct tm tmtime, tmzero;
enum utc_cmptype relation;
utc_t testtime;
/* Zero the tm structure for inaccuracy...
*/
memset(&tmzero, 0, sizeof(tmzero));
/* Get the current time, mapped to a tm structure...
*
* NOTE: The NULL argument is used to get the current time.
*/
utc_gmtime(&tmtime, /* Out: Current GMT time in tm struct */
(long *)0, /* Out: Nanoseconds of time */
(struct tm *)0, /* Out: Current inaccuracy in tm struct */
(long *)0, /* Out: Nanoseconds of inaccuracy */
(utc_t *)0); /* In: Current timestamp */
/* Alter the tm structure to correspond to 13:00 local time */
*/
tmtime.tm_hour = 13;
tmtime.tm_min = 0;
tmtime.tm_sec = 0;
/* Convert to a binary timestamp...
*/
utc_mkgmtime(&testtime, /* Out: Binary timestamp of 13:00 */
&tmtime, /* In: 1:00 PM in tm struct */
0, /* In: Nanoseconds of time */
&tmzero, /* In: Zero inaccuracy in tm struct */
0); /* In: Nanoseconds of inaccuracy */
/* Compare to the current time. Note the use of the NULL argument */
*/
utc_cmpintervaltime(&relation, /* Out: Comparison relation */
(utc_t *)0, /* In: Current timestamp */
&testtime); /* In: 13:00 PM timestamp */
/* If it is not later - wait, print a message, etc.
*/
if (relation != utc_greaterThan) {
/*
* Note: It could be earlier than 13:00 local time or it could be
* indeterminate. If indeterminate, for some applications
* it might be worth waiting.
*/
}

Related Information
Function: utc_cmpmidtime(3dts)