function create_index,a,nrec,update=update,outfile=outfile
; These constants should be changed in coordination with ARCHIVE
nbytperentry = 38
; NB: This list should be of even number. If it is not, add a zero to the end.
template_codes = [!SEGM.GPARM, !SEGM.TPCAL,!SEGM.AMPCAL,$
!SEGM.PHZCAL,!SEGM.EPHEM,!SEGM.TPUPD]
n_templ = n_elements(template_codes)
; As a precaution, check that there is not already an INDEX segment
rec = (find_index(a,nrec) - 1)[0]
indrec = nrec
if (keyword_set(update) and rec ne -2) then begin
indrec = rec ; INDEX segment exists, but we want to update it
endif else begin
if (rec ne -2) then return,rec+1 ; INDEX segment already exists, so return its rec #
endelse
; It did not already exist, so try to create one
; First open file for update and try to append an empty record, to see if it is
; possible to write to the file (it may be on read-only media).
; Get the file name associated with ASSOC variable A (note it is dangerous
; to parse the HELP command output like this...)
help,a,output=afile
afile = afile[0]
bra = strpos(afile,'<')+1
ket = strpos(afile,'>')
filename = strmid(afile,bra,ket-bra)
; If the OUTVAR is not set, then we are writing the INDEX record to the existing
; file, so take care of some things for this case.
if (not keyword_set(outfile)) then begin
; Check if this is a readonly file, in which case we cannot add or
; update the INDEX records.
if (is_rd_only(filename)) then goto,skip
if (indrec eq nrec) then begin
; Check if the last record of the file is an EOF record (a few were written
; with EOF = 100, now EOF = 17). If so, decrement NREC so that the EOF will
; be overwritten.
tls = tl_decode(a(nrec-1))
if (tls.segmentcode eq !SEGM.EOF or tls.segmentcode eq 100) then nrec = nrec-1
indrec = nrec
endif
; Seems to have worked, so it is worthwhile to create the index record
; Index record number will be just NREC+1
openu,lun,/get_lun,filename
b = assoc(lun,intarr(1024)) ; Associate a second variable B to the file
endif else begin
; OUTFILE is set, so we are writing to a new file.
openw,olun,/get_lun,outfile
b = assoc(olun,intarr(1024))
indrec = 0
endelse
; Generate the T/L field and the template for the scan entries
data = a(0)
tls = tl_decode(data)
tls.segmentcode = 16 ; INDEX segment
tls.scancode = 1 ; TEST scan (scan number is not defined for INDEX)
tls.nrc = indrec+1 ; Current record number
tls.nro = 0 ; Original record number (not defined)
tls.nrs = 1 ; Which record of the segment this is (1st)
; Encode changed T/L field back to binary data
tlsdat = tl_encode(tls)
; Create blank record and start filling it in
data = intarr(1024)
data[0:11] = tlsdat
data[12] = uint(ishft(n_templ,8) + nbytperentry)
; Fill in template bytes
for i = 0, n_templ-1, 2 do begin
data[13+i/2] = uint(ishft(template_codes[i+1],8) + template_codes[i])
endfor
; Pointer to start of next INDEX entry
inext = 13+n_templ/2
; Save "boiler plate" info that gets written to each record
bplate = data[12:inext-1]
; Get the list of scan headers and segments not in a scan
seglist = get_segments(a,nrec)
ntot = findsegentries(seglist,ihed,iseg)
nhed = n_elements(ihed)
nseg = n_elements(iseg)
recs = intarr(n_templ) ; Template record numbers
id = progmeter(/init)
; Loop over scan headers
for i = 0, nhed-1 do begin
res = progmeter(id,i*1.0/ntot)
if (ihed[i] ne -1) then begin
; Get info from each scan for index entries
; Get start and end record numbers
reads,seglist[ihed[i]],srec,erec,format='(13X,I5,1X,I5)'
; Get start and end date and time
tdata = a(srec-1)
scansegcodes = tdata[2]
tlsnew = tl_decode(tdata)
syr = tlsnew.year
sday = tlsnew.day
smsec = tlsnew.msec
tdata = a(erec-1)
tlsnew = tl_decode(tdata)
eyr = tlsnew.year
eday = tlsnew.day
emsec = tlsnew.msec
; Get TRAJECTORY segment for source name and pointing offsets
trec = findseg(a,srec,nrec,!SEGM.TRAJ)
if (trec eq -1) then begin
; No TRAJECTORY structure, so fill in with nominal.
bytsrcnam = byte('<UNKNOWN> ')
srcnamdat = uintarr(6)
; Pack 2-byte data with byte-character data from sourcename
for j = 0, 5 do begin
srcnamdat[j] = ishft(uint(bytsrcnam[j*2+1]),8) + uint(bytsrcnam[j*2])
endfor
hao = 0
deco = 0
endif else begin
tdata = a(trec-1)
srcnamdat = tdata[12:17]
traj = decode(tdata,!SEGM.TRAJ)
hao = uint((*traj.pha)[ 0]) ; HA offset [mdeg]
deco = uint((*traj.pdec)[0]) ; Dec offset [mdeg]
endelse
; Get the start records of the appropriate segments from the template.
; If no appropriate record is found within the scan, FINDSEG returns
; -1, in which case the next earlier relevant record number is used.
for j = 0, n_templ-1 do recs[j] = recs[j] > findseg(a,srec,nrec,template_codes[j])
; Finally have all of the info, so create the INDEX entry for this scan
data[inext] = scansegcodes
data[inext+1] = srec
data[inext+2] = erec
data[inext+3] = syr
data[inext+4] = sday
data[inext+5:inext+6] = [uint(smsec),ishft(smsec,-16)]
data[inext+7] = eyr
data[inext+8] = eday
data[inext+9:inext+10] = [uint(emsec),ishft(emsec,-16)]
data[inext+11:inext+16] = srcnamdat
data[inext+17] = hao
data[inext+18] = deco
for j = 0, n_templ-1 do data[inext+19+j] = recs[j]
; That INDEX entry is complete. Advance the pointer for the next
; INDEX entry and check that it has not filled the current record
inext = inext+nbytperentry/2+n_templ
if (inext + nbytperentry/2 + n_templ gt 1024) then begin
; The next entry is not going to fit into this record, so
; write it to the file and prepare a new one
b(indrec) = data ; Write out current record
indrec = indrec + 1 ; Increment total number of records
tls.nrc = indrec+1 ; Current record number
tls.nro = 0 ; Original record number (not defined)
tls.nrs = tls.nrs+1 ; Which record of the segment this is
; Encode changed T/L field back to binary data
tlsdat = tl_encode(tls)
data = intarr(1024) ; Zero the next record
data[0:11] = tlsdat ; Entry T/L Field
inext = 13+n_templ/2 ; Starting pointer for this record
data[12:inext-1] = bplate ; Insert "boiler plate" info
endif
endif
endfor
res = progmeter(id,nhed*1.0/ntot)
nstarted = tls.nrs
; Scans are all done. Write out blank records to a total of 9
for i = 0, 9-nstarted do begin
b(indrec) = data ; Write out current (partially filled) record
indrec = indrec + 1 ; Increment total number of records
tls.nrc = indrec+1 ; Current record number
tls.nro = 0 ; Original record number (not defined)
tls.nrs = tls.nrs+1 ; Which record of the segment this is
; Encode changed T/L field back to binary data
tlsdat = tl_encode(tls)
data = intarr(1024) ; Zero the next record
data[0:11] = tlsdat ; Entry T/L Field
inext = 13+n_templ/2 ; Starting pointer for this record
data[12:inext-1] = bplate ; Insert "boiler plate" info
endfor
; Now at the last (10th) INDEX segment record. Enter info for special segments
for i = 0, nseg-1 do begin
res = progmeter(id,(i+nhed)*1.0/ntot)
if (iseg[i] ne -1) then begin
; Get info from each scan for index entries
; Get start record number
reads,seglist[iseg[i]],srec,format='(13X,I5)'
; Get start date and time
tdata = a(srec-1)
tlsnew = tl_decode(tdata)
segcode = tlsnew.segmentcode
syr = tlsnew.year
sday = tlsnew.day
smsec = tlsnew.msec
; Finally have all of the info, so create the INDEX entry for this segment
data[inext] = segcode
data[inext+1] = srec
data[inext+2] = syr
data[inext+3] = sday
data[inext+4:inext+5] = [uint(smsec),ishft(smsec,-16)]
; That INDEX entry is complete. Advance the pointer for the next
; INDEX entry and check that it has not filled the current record
inext = inext+6
endif
endfor
b(indrec) = data
indrec = indrec+1
if (n_elements(lun) ne 0) then free_lun,lun
if (n_elements(olun) ne 0) then free_lun,olun
res = progmeter(id,/destroy)
return,indrec
skip:
; There was an error opening or writing the file
ON_IOERROR,NULL
if (n_elements(lun) ne 0) then free_lun,lun
if (n_elements(olun) ne 0) then free_lun,olun
ans = dialog_message(['CREATE_INDEX: An error occurred in trying to write the',$
'INDEX segment. The file may be on read-only media.'],/error)
return,-1
en