; 
; PURPOSE:  Calculate date and time that correspond to a fractional crn:Cl0
; CALLING SEQUENCE :
;  datetime_scrncl0_200905,crn,cl0,reso=,year,month,day,hh,mm,ss,/dtl
; IUPUT:   crn,cl0,reso=
; OUTPUT:  year,month,day,hh,mm,ss,/dtl
; MODIFICATION HISTORY :
;    First version: 20090531 by X. Zhao based on datetime_scrncl0.pro
;                   20060327 by X. Zhao
;
pro datetime_scrncl0_200905,crn,cl0,RESO=reso,cl0i,year,month,day1,DTL=dtl

    if N_params() LT 1 then begin
       print,'datetime_scrncl0_200905,crn,cl0,reso=,cl0i,year,month,day1,/dtl'
       print,"crn=2081 & cl0=180.50"
       print,"resolution of 600sec., 60sec, 10sec and 1sec"
       return
    endif
    CASE 1 OF
     reso eq 360: lim=0.166667
     reso eq 100: lim=0.05
     reso eq 60:  lim=0.0166667
     reso eq 10:  lim=0.00277778
     reso eq 1:   lim=0.000277778
    ENDCASE 
    scrncl0=STRTRIM(crn,2)+':'+STRTRIM(FIX(cl0),2)
    spawn,'times ct'+scrncl0+' > outdata.d'
    date0=' '
    get_lun,unit
    openr,unit,'outdata.d'
    readf,unit,date0
    free_lun,unit
    spawn,'rm outdata.d'
    year  = fix(strmid(date0,0,4))
    month = fix(strmid(date0,5,2))
    day   = fix(strmid(date0,8,2))
    hrs00=FIX(STRMID(date0,11,2))
    hrs01=FIX(STRMID(date0,15,2))/60.+FIX(STRMID(date0,19,2))/3600.
    hrs0=hrs00+hrs01
    days0=day+hrs0/24.
    cl0_yyyymmddtime,year,month,day,hrs0,cl0i
    dcl=cl0i-cl0
    if ABS(dcl) gt 100 then cl0i=cl0i+360
    dcl=cl0i-cl0
if keyword_set(dtl) then begin
print,'date0,hrs0:',date0,hrs0
print,'cl0,First cl0i:',cl0,cl0i
endif
    CASE 1 OF
; Case 1
       dcl gt lim: begin
                   if hrs00 eq 23 then begin
                      day=day+1
                      hrs0=hrs01
                      hrs=hrs0
                   endif else hrs=hrs0
        lbl1:      hrs=hrs+lim              ;hrs=hrs+1.
                   cl0_yyyymmddtime,year,month,day,hrs,cl0i
                   dcl=cl0i-cl0
                   if ABS(dcl) gt 100 then cl0i=cl0i+360
                   dcl=cl0i-cl0
         if keyword_set(dtl) then print,'C1-cl0i,dcl:',cl0i,dcl
                   CASE 1 OF
                      dcl gt lim: goto, lbl1 
                      dcl lt -lim: begin
        lbl2:                   hrs=hrs-lim
                                cl0_yyyymmddtime,year,month,day,hrs,cl0i
                                dcl=cl0i-cl0
         if keyword_set(dtl) then print,'C1-cl0i,dcl:',cl0i,dcl
                                if dcl lt -lim then goto, lbl2 $
                                else day1=day+hrs/24.
                                   end
                      else: day1=day+hrs/24.
                   ENDCASE
                   end
; Case 2
       dcl lt -lim: begin
                    if hrs00 eq 0 then begin
                       day=day-1
                       hrs0=24+hrs01
                       hrs=hrs0
                    endif else hrs=hrs0
        lbl3:      hrs=hrs-lim
                   cl0_yyyymmddtime,year,month,day,hrs,cl0i
                   dcl=cl0i-cl0
        if keyword_set(dtl) then  print,'C2-day,hrs,cl0i,dcl:',day,hrs,cl0i,dcl
                   CASE 1 OF
                      dcl lt -lim: goto, lbl3
                      dcl gt lim: begin
                      ;         hrs=hrs+1.
        lbl4:                   hrs=hrs+lim
                                cl0_yyyymmddtime,year,month,day,hrs,cl0i
                                dcl=cl0i-cl0
        if keyword_set(dtl) then  print,'C2-day,hrs,cl0i,dcl:',day,hrs,cl0i,dcl
                                if dcl gt lim then goto, lbl4 $
                                else day1=day+hrs/24.
                                end
                      else: day1=day+hrs/24.
                   ENDCASE
                    end
       else: day1=day+hrs0/24.
     ENDCASE
     hrs1=(day1-day)*24.
     hh=FIX(hrs1) & mm=FIX((hrs1-hh)*60) & ss=FIX((hrs1-hh)*3600-mm*60)
     if hh eq 24 then begin
        day=day+1
        hh=0
     endif
     if keyword_set(dtl) then begin
        date_year_sec,year,month,day,hh,mm,ss,date1
        print,'Orig. cl0 and date0 from times:',cl0,' ',date0
        print,'Last cl0i and date1           :',cl0i,' ',date1
     endif

end