pro dbext_dbf,list,dbno,sbyte,nbytes,idltype,nval,v1,v2,v3,v4,v5,v6, $
v7,v8,v9,v10,v11,v12,v13,v14,v15,v16,v17,v18, item_dbno=item_dbno
;+
; NAME:
; DBEXT_DBF
; PURPOSE:
; Subroutine of DBEXT to extract values of up to 18 items from a database
; EXPLANATION:
; This is a subroutine of DBEXT, which is the routine a user should
; normally use.
;
; CALLING SEQUENCE:
; dbext_dbf,list,dbno,sbyte,nbytes,idltype,nval,v1,[ v2,v3,v4,v5,v6,v7,
; v8,v9,v10,v11,v12,v13,v14,v15,v16,v17,v18 ITEM_DBNO = ]
;
; INPUTS:
; list - list of entry numbers to extract desired items. It is the
; entry numbers in the primary data base unless dbno is greater
; than or equal to -1. In that case it is the entry number in
; the specified data base.
; dbno - number of the opened db file
; if set to -1 then all data bases are included
; sbyte - starting byte in the entry. If single data base then it must
; be the starting byte for that data base only and not the
; concatenation of db records
; nbytes - number of bytes in the entry
; idltype - idl data type of each item to be extracted
; nval - number of values per entry of each item to be extracted
;
; OUTPUTS:
; v1...v18 - the vectors of values for up to 18 items
;
; OPTIONAL INPUT KEYWORD:
; item_dbno - A vector of the individual database numbers for each item.
; Simplifies the code for linked databases
; PROCEDURE CALLS:
; DB_INFO(), DB_ITEM_INFO(), DBRD, DBXVAL(), IS_IEEE_BIG(), IEEE_TO_HOST
; HISTORY
; version 1 D. Lindler Nov. 1987
; Extract multiple valued entries W. Landsman May 1989
; William Thompson, GSFC/CDS (ARC), 1 June 1994
; Added support for external (IEEE) representation.
; Work with multiple element string items W. Landsman August 1995
; Increase speed for external databases on IEEE machines WBL August 1996
; IEEE conversion implemented on blocks of entries using BIG
; Added keyword ITEM_DBNO R. Schwartz, GSFC/SDAC, August 1996
; Return a vector even if only 1 value W. Thompson October 1996
; Change variable name of BYTESWAP to BSWAP W. Thompson Mar 1997
; Use /OVERWRITE with reform W. Landsman May 1997
; Converted to IDL V5.0 W. Landsman September 1997
; Increase maximum number of items to 18 W. Landsman November 1999
; 2 May 2003, W. Thompson, Use DBXVAL with BSWAP instead of IEEE_TO_HOST.
;-
;
;*****************************************************************
;
COMMON db_com,qdb,qitems,qdbrec
nitems=n_elements(sbyte) ;number of items
external = db_info('external') ;External format?
bswap = external * (not IS_IEEE_BIG() ) ;Need to byteswap?
if dbno ge 0 then bswap = bswap[dbno] + bytarr(nitems) else $
if n_elements(item_dbno) eq nitems then bswap=bswap[item_dbno] $
else begin
sbyte1 = db_item_info('bytepos')
itnums = intarr(nitems)
for i=0,nitems-1 do itnums[i] = (where( sbyte[i] eq sbyte1))[0]
dbno1 = db_item_info('dbnumber', itnums)
bswap = bswap[dbno1]
endelse
scalar=0
if n_elements(list) eq 1 then begin
scalar=1
savelist=list
list=lonarr(1)+list
if list[0] eq -1 then list=lindgen(db_info('entries',0))+1
end
nlist=n_elements(list)
;
; create a big array to hold all extracted values in
; byte format
;
totbytes=total(nbytes)
big=bytarr(totbytes,nlist)
;
; generate vector of bytes in entries to extract
;
index=intarr(totbytes)
ipos=0
for i=0,nitems-1 do begin
for j=0,nbytes[i]-1 do index[ipos+j]=sbyte[i]+j
ipos=ipos+nbytes[i]
endfor
;
; generate vector of byte positions in big for each item
;
bpos=intarr(nitems)
if nitems gt 1 then for i=1,nitems-1 do bpos[i]=bpos[i-1]+nbytes[i-1]
;
; loop on records and extract info into big
;
if dbno ge 0 then begin
;
; bypass dbrd for increased performance
;
if dbno eq 0 then begin
for i=0L,nlist-1 do begin
if list[i] ge 0 then begin
entry=qdbrec[list[i]]
big[0,i] = entry[index]
endif
endfor
end else begin ;mapped I/O
unit=db_info('unit_dbf',dbno)
rec_size=db_info('length',dbno)
for i=0L,nlist-1 do begin
if list[i] ge 0 then begin
p=assoc(unit,bytarr(rec_size,/nozero),rec_size*list[i])
entry=p[0]
big[0,i] = entry[index]
end
endfor
end
end else begin
for i = 0L, nlist-1 do begin
if list[i] GE 0 then begin
dbrd,list[i],entry, /noconvert
big[0,i] = entry[index]
endif
end
end
;
; now extract each value and convert to correct type
;
last = bpos + nbytes -1
for i = 0,nitems-1 do begin
item = dbxval(big, idltype[i], nval[i], bpos[i], nbytes[i], bswap=bswap[i])
;; if bswap[i] then ieee_to_host, item, idltype = idltype[i]
st = 'v' + strtrim(i+1,2)
if nlist GT 1 then $
st = st + '= reform(item, /overwrite)' else $
st = st + '= [item]'
;
; copy v to correct output vector
;
status = execute(st)
;
; create line of form v<i> = v and execute it
;
end;for i loop on items
if scalar then list=savelist ;restore scalar value
return
end