;+ ; NAME: ; GET_CYCLE ; PURPOSE: ; Returns one cycle of data, and the time corresponding to the beginning ; of the cycle. This routine can be called repeatedly to return a ; sequence of cycles of data, as long as the DATA array is not modified ; between calls. ; CATEGORY: ; OVRO APC DATA ; CALLING SEQUENCE: ; cycle = get_cycle(a,data,currec,header,obseq,cfg,tcycle) ; INPUTS: ; a A file associated variable as returned from OPENARC. ; data Must be a named variable. On input, DATA contains the data ; that have been read during a previous call to GET_CYCLE(). ; On the first call, DATA should be undefined (i.e. either ; not previously referenced, or use DELVAR,DATA before the ; first call). ; header The HEADER structure corresponding to the data. ; obseq The OBSEQ structure corresponding to the data. ; cfg The CONFIG structure corresponding to the data. ; tcycle Must be a named variable. On input, TCYCLE contains the ; start time [msec] returned by a previous call to GET_CYCLE(). ; On the first call, TCYCLE may be anything, or undefined. ; OPTIONAL (KEYWORD) INPUT PARAMETERS: ; ROUTINES CALLED: ; getdata, tl_decode ; OUTPUTS: ; cycle Contains one cycle of data as a simple, linear array of ; samples of length HEADER.NWS*OBSEQ.NX, where HEADER.NWS ; is the number of words in a sample and OBSEQ.NX is the ; number of samples in an observing sequence. If no more ; data can be read due to a zero record (indicating that the ; file is still being written), CYCLE = 0. If no more data ; can be read due to reading a non-data record, a partial cycle ; of data may be returned. If a non-data record is read, ; the segmentcode of the record is returned. ; data Must be a named variable. On output, DATA contains the data ; that have been read during the call to GET_CYCLE(), but not ; yet placed into the CYCLE output variable. On the first ; call, DATA should be undefined (i.e. either not previously ; referenced, or use DELVAR,DATA before the first call). ; tcycle Must be a named variable. On output, TCYCLE contains the ; start time [msec] of the cycle returned in CYCLE. If CYCLE = 0, ; TCYCLE should be ignored. ; COMMENTS: ; Do not change the contents of DATA or TCYCLE between calls to GET_CYCLE(). ; SIDE EFFECTS: ; RESTRICTIONS: ; This routine is going to break if the DATA segment is broken up by ; non-data segments (e.g. Engineering segments) ; MODIFICATION HISTORY: ; Written 12-Jan-1999 by Dale E. Gary ; 20-Jan-1999 DG ; Added code to indicate that a zero record has been read (i.e., the file ; is still being actively written to). The calling routine can wait for ; some time, then try again. ; 15-Mar-1999 DG ; Added detection of EOS segment, in which case the routine returns a -1. ; 14-May-1999 DG ; Change EOS detection to more general returning of segment code. ; Major rewrite to solve some problems: ; 1. The cycle time was 200 ms off due to not taking KOFF into account ; 2. GET_CYCLE could not find the start of a cycle unless it was ; called with the first record in the scan. This has been relaxed ; so that it can be called with any record. ; 22-Jan-2000 DG ; First attempt to make the code work over a day change within a scan ; 28-Mar-2000 DG ; Made change to account for newly determined timing issue--the time/label ; field has a time that is one sample "late" since it is the time ; corresponding to the end of acquisition of the first sample. Variable ; NSOFF takes care of this. Also fixed a round-off problem introduced ; in my code to account for a day change--amounted to 2 msec. ; 11-Mar-2001 DG ; Fixed long-standing bug that caused "dead reckoning" in start from middle ; of a scan to fail if the start was somewhere within the first cycle. ; 08-Feb-2002 DG ; GET_CYCLE failed if the first record after a TRAJECTORY was not a data ; record. Added a check for this. Note that first call to GET_CYCLE ; should now be WHILE (n_elements(data) eq 0) DO get_cycle,... ; 03-Mar-2002 DG ; FLAREMETER was getting into an infinite loop. Added code to return an ; EOF segment code when a file read error occurs. ;- function get_cycle,a,data,currec,header,obseq,cfg,tcycle,tls ; First two samples are no good (not part of an observing sequence), ; so this represents a perpetual offset to the cycle. koff = 2 nws = header.nws noff = koff*nws ; Number of words in two samples that are no good nsoff = 1 ; Number of samples "late" for time in Time/Label field nsr = header.nsr rdoff = header.rdoff ; Number of words before data start nx = obseq.nx ncycle = nws*nx ; Number of words in a cycle nrecord = nws*nsr ; Number of words in a record t = lonarr(10) curpos = long(n_elements(data)) if (curpos gt 0) then begin good = data ; Put the rest of DATA into "good" array endif else begin ; The DATA array is undefined, so this is the first call. ; Read records until the start of a cycle is found sod = -1 ; SOD = Start of Data while (sod lt 0) do begin currec = currec+1 tmpdata = getdata(currec,a) if (tmpdata(0) eq 0 or tmpdata(0) eq -1) then begin if (tmpdata[0] eq -1 and n_elements(tmpdata) eq 1) then begin ; If file is no longer growing, return an EOF filestr = fstat(a) if (filestr.cur_ptr le filestr.size) then return,!SEGM.EOF endif ; There is no new record waiting, so put things back as they ; were before the call and return a zero to indicate end of file. ; If the calling procedure gets a zero, it can wait and try again. currec = currec - 1 return,0 endif tls = tl_decode(tmpdata) if (tls.segmentcode ne 7) then return,0 ; Skip this record if not DATA ; Index of start of data (not including NOFF or RDOFF) sod = (nrecord - (long(nrecord)*tls.nrs mod ncycle)) ;mod nrecord if (sod ge nrecord) then return,0 ; Skip this record if SOD is beyond end of record endwhile good = tmpdata[sod+rdoff:rdoff+nrecord-1] tcycle = tls.msec + ((sod+noff)/nws - nsoff)*cfg.sampintms $ + 86400000L*(tls.day-header.tls.day) ; Add 24h if day change endelse ; Determine the current start position of the data, for calculating ; the start time of the cycle. curpos = n_elements(good) ; Read records and add to "good" array until an entire cycle ; has been read. firstrec = currec while n_elements(good) lt (ncycle+NOFF) do begin currec = currec+1 data = getdata(currec,a) if (data(0) eq 0 or data(0) eq -1) then begin if (data[0] eq -1 and n_elements(data) eq 1) then begin ; If file is no longer growing, return an EOF filestr = fstat(a) if (filestr.cur_ptr le filestr.size) then return,!SEGM.EOF endif ; There is no new record waiting, so put things back as they ; were before the call and return a zero to indicate end of file. ; If the calling procedure gets a zero, it can wait and try again. currec = currec - 1 if (curpos gt 0) then data = good return,0 endif tls = tl_decode(data) ; Read delay bits from data record ; dla = get_delaybits(data) ; printf,2,tls.msec,dla ; print,tls.msec,data[12]-data[13]- cfg.dlacent[0]+ cfg.dlacent[1] t(currec-firstrec-1) = tls.msec $ + 86400000L*(tls.day-header.tls.day) ; Add 24h if day change if (tls.segmentcode ne 7) then begin ; This is not a data record, so return with partial contents cycle = good data = good ; Determine start time of cycle from previous start time, adding ; one cycle of time tcycle = tcycle + obseq.nx*cfg.sampintms ; Return the segmentcode, to which the calling procedure should ; act accordingly cycle = tls.segmentcode return,cycle endif if (n_elements(good) gt 0) then begin good = [good,data(rdoff:rdoff+nrecord-1)] endif else begin good = data(rdoff:rdoff+nrecord-1) endelse endwhile ; An entire cycle has been read, so extract it from the "good" array cycle = good(noff:noff+ncycle-1) ; If the T array is zero, the cycle is smaller than a record and we ; have to determine the time from dead-reckoning from the previous time. if (t(0) eq 0) then begin ; Determine start time of cycle from previous start time, adding ; one cycle of time tcycle = tcycle + obseq.nx*cfg.sampintms endif else begin ; This cycle bridges two records, so determine the start time ; from the start time of the next record. tcycle = t(0) - ((curpos-noff)/header.nws + nsoff)*cfg.sampintms endelse ; Put the rest of the good data into the "data" array (keeping KOFF ; samples from previous cycle so that KOFF remains equal to 2 for ; subsequent calls to this routine). data = good(ncycle:*) good = where(t ne 0) return,cycle end