FreeBASIC  0.91.0
time_dateadd.c
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1 /* dateadd function */
2 
3 #include "fb.h"
4 
5 /*:::::*/
6 FBCALL double fb_DateAdd( FBSTRING *interval, double interval_value_arg, double serial )
7 {
8  int year, month, day, hour, minute, second;
9  int carry_value, test_value;
10  int interval_value = (int) fb_FIXDouble( interval_value_arg );
11  int interval_type = fb_hTimeGetIntervalType( interval );
12 
13  fb_ErrorSetNum( FB_RTERROR_OK );
14 
15  fb_hTimeDecodeSerial ( serial, &hour, &minute, &second, FALSE );
16  fb_hDateDecodeSerial ( serial, &year, &month, &day );
17 
18  switch ( interval_type ) {
19  case FB_TIME_INTERVAL_YEAR:
20  year += interval_value;
21  break;
22  case FB_TIME_INTERVAL_QUARTER:
23  month += interval_value * 3;
24  break;
25  case FB_TIME_INTERVAL_MONTH:
26  month += interval_value;
27  break;
28  case FB_TIME_INTERVAL_DAY_OF_YEAR:
29  case FB_TIME_INTERVAL_DAY:
30  case FB_TIME_INTERVAL_WEEKDAY:
31  day += interval_value;
32  break;
33  case FB_TIME_INTERVAL_WEEK_OF_YEAR:
34  day += interval_value * 7;
35  break;
36  case FB_TIME_INTERVAL_HOUR:
37  hour += interval_value;
38  break;
39  case FB_TIME_INTERVAL_MINUTE:
40  minute += interval_value;
41  break;
42  case FB_TIME_INTERVAL_SECOND:
43  second += interval_value;
44  break;
45  case FB_TIME_INTERVAL_INVALID:
46  default:
47  fb_ErrorSetNum( FB_RTERROR_ILLEGALFUNCTIONCALL );
48  break;
49  }
50 
51  /* Normalize date/time */
52  switch ( interval_type ) {
53  case FB_TIME_INTERVAL_HOUR:
54  case FB_TIME_INTERVAL_MINUTE:
55  case FB_TIME_INTERVAL_SECOND:
56  case FB_TIME_INTERVAL_DAY_OF_YEAR:
57  case FB_TIME_INTERVAL_DAY:
58  case FB_TIME_INTERVAL_WEEKDAY:
59  case FB_TIME_INTERVAL_WEEK_OF_YEAR:
60  /* Nothing to do here because normalization will implicitly be done
61  * by the calculation of the new serial number. */
62  break;
63 
64  case FB_TIME_INTERVAL_YEAR:
65  case FB_TIME_INTERVAL_QUARTER:
66  case FB_TIME_INTERVAL_MONTH:
67  /* Handle wrap-around for month */
68  if( month < 1 ) {
69  carry_value = (month - 12) / 12;
70  } else {
71  carry_value = (month - 1) / 12;
72  }
73  year += carry_value;
74  month -= carry_value * 12;
75  /* No wrap-around ... instead we must saturate the day */
76  test_value = fb_hTimeDaysInMonth( month, year );
77  if( day > test_value )
78  day = test_value;
79  break;
80 
81  }
82 
83  serial = fb_DateSerial( year, month, day ) +
84  fb_TimeSerial( hour, minute, second );
85 
86  return serial;
87 }