Set the trigger date to the previous date according to the periodicity and rules

Declared in file: hzCron.h
Defined in file : hzCron.cpp

Function Logic:

Function body:

hzEcode hzCron::Retard (hzXDate& date)uint32_t factor, 
{
   //  Set the trigger date to the previous date according to the periodicity and rules
   //  
   //  Arguments: 1) date Full date and time
   //     2) factor No of intervals to retard
   //  
   //  Returns: E_ARGUMENT If the number of intervals to retard is zero
   //     E_NOINIT If this hzCron is not active or cannot be retarded
   //     E_OK  If this hzCron set the date of the previous occurance
   _hzfunc("hzCron::Advance(hzXDate)") ;
   uint32_t    Y ;     //  Year
   uint32_t    M ;     //  Month
   uint32_t    dow ;   //  Day of week
   uint32_t    alt ;   //  No of days to retard
   if (!m_bActive)
   {
       date.Clear() ;
       m_error = "Interval not active" ;
       return E_NOINIT ;
   }
   if (factor < 1)
   {
       m_error = "Factor must be 1 or more" ;
       return E_ARGUMENT ;
   }
   if (!date.IsSet())
       date.SysDateTime() ;
   do
   {
       Y = date.Year() ;
       M = date.Month() ;
       dow = date.Dow() ;
       //  Every day
       if      (m_Period == HZPERIOD_DAY)      { alt = 1; date.altdate(DAY, -alt) ; }
       //  Mon - Sat",
       else if (m_Period == HZPERIOD_MONSAT)   { alt = dow==0? 2: 1; date.altdate(DAY, -alt) ; }
       //  Weekdays only
       else if (m_Period == HZPERIOD_WEEKDAY)  { alt = dow>4? dow - 4: dow ? 1: 3; date.altdate(DAY, -alt) ; }
       //  Every [Monday - Friday]
       else if (m_Period == HZPERIOD_EMON)     { alt = dow>0? dow : 7; date.altdate(DAY, -alt) ; }
       else if (m_Period == HZPERIOD_ETUE)     { alt = dow>1? dow - 1: dow + 6; date.altdate(DAY, -alt) ; }
       else if (m_Period == HZPERIOD_EWED)     { alt = dow>2? dow - 2: dow + 5; date.altdate(DAY, -alt) ; }
       else if (m_Period == HZPERIOD_ETHR)     { alt = dow>3? dow - 3: dow + 4; date.altdate(DAY, -alt) ; }
       else if (m_Period == HZPERIOD_EFRI)     { alt = dow>4? dow - 4: dow + 3; date.altdate(DAY, -alt) ; }
       else if (m_Period == HZPERIOD_ESAT)     { alt = dow>5? dow - 5: dow + 2; date.altdate(DAY, -alt) ; }
       else if (m_Period == HZPERIOD_ESUN)     { alt = dow + 1; date.altdate(DAY, -alt) ; }
       //  Every other [Monday - Friday]
       else if (m_Period == HZPERIOD_ALT_MON)  { alt = dow>0? dow : 7; alt += 7; date.altdate(DAY, -alt) ; }
       else if (m_Period == HZPERIOD_ALT_TUE)  { alt = dow>1? dow - 1: dow + 6; alt += 7; date.altdate(DAY, -alt) ; }
       else if (m_Period == HZPERIOD_ALT_WED)  { alt = dow>2? dow - 2: dow + 5; alt += 7; date.altdate(DAY, -alt) ; }
       else if (m_Period == HZPERIOD_ALT_THR)  { alt = dow>3? dow - 3: dow + 4; alt += 7; date.altdate(DAY, -alt) ; }
       else if (m_Period == HZPERIOD_ALT_FRI)  { alt = dow>4? dow - 4: dow + 3; alt += 7; date.altdate(DAY, -alt) ; }
       else if (m_Period == HZPERIOD_ALT_SAT)  { alt = dow>5? dow - 5: dow + 2; alt += 7; date.altdate(DAY, -alt) ; }
       else if (m_Period == HZPERIOD_ALT_SUN)  { alt = dow + 1; alt += 7; date.altdate(DAY, -alt) ; }
       else
       {
           switch  (m_Period)
           {
           //  Monthly
           case HZPERIOD_MONTH:
               M-- ; break ;
           //  Bi-monthly [odd/even]
           case HZPERIOD_MONTH1:
           case HZPERIOD_MONTH2:
               alt = M % 2; M -= alt ? alt : 2; break ;
           //  Quarterly [month1 - month3]
           case HZPERIOD_QTR1: case HZPERIOD_QTR2: case HZPERIOD_QTR3:
               alt = M % 3; M -= alt ? alt : 3; break ;
           //  Half yearly [month1 - month6]
           case HZPERIOD_HYEAR1: case HZPERIOD_HYEAR2: case HZPERIOD_HYEAR3: case HZPERIOD_HYEAR4: case HZPERIOD_HYEAR5: case HZPERIOD_HYEAR6:
               alt = M % 6; M -= alt ? alt : 6; break ;
           //  Every [Jan - Dec]
           case HZPERIOD_YEAR1: case HZPERIOD_YEAR2: case HZPERIOD_YEAR3: case HZPERIOD_YEAR4: case HZPERIOD_YEAR5: case HZPERIOD_YEAR6:
           case HZPERIOD_YEAR7: case HZPERIOD_YEAR8: case HZPERIOD_YEAR9: case HZPERIOD_YEAR10: case HZPERIOD_YEAR11: case HZPERIOD_YEAR12:
               Y-- ; break ;
           }
           if (M < 1)
               { Y-- ; M += 12;}
           date.SetDate(Y, M, 1);
       }
       //  Have arrived at a possible date. Check if this is not excluded. If it is we do not decrement the factor
       if (!IsHoliday(date, m_exclhols))
           factor-- ;
   }
   while (factor) ;
   return E_OK ;
}