dbopen.pro

来自「basic median filter simulation」· PRO 代码 · 共 367 行

pro dbopen,name,update,UNAVAIL=unavail   
;+
; NAME:
;       DBOPEN
; PURPOSE:
;       Routine to open an IDL database
;
; CALLING SEQUENCE:
;       dbopen, name, update
;
; INPUTS:
;       name - (Optional) name or names of the data base files to open.
;               It has one of the following forms:
;
;               'name'          -open single data base file
;               'name1,name2,...,nameN' - open N files which are
;                               connected via pointers.
;               'name,*'        -Open the data base with all data
;                               bases connected via pointers
;               ''              -Interactively allow selection of
;                               the data base files.
;
;               If not supplied then '' is assumed.
;               name may optionally be a string array with one name
;               per element.
;
;       update - (Optional) Integer flag specifing openning for update.
;               0       - Open for read only
;               1       - Open for update
;               2       - Open index file for update only
;               !PRIV must be 2 or greater to open a file for update.
;               If a file is opened for update only a single data base
;               can be specified.
;
; OUTPUTS:
;       none
;
; INPUT-OUTPUT KEYWORD:
;       UNAVAIL - If present, a "database doesn't exit" flag is returned
;                 through it.  0 = the database exists and was opened (if
;                 no other errors arose).  1 = the database doesn't exist.
;                 Also if present, the error message for non-existent databases
;                 is suppressed.  The action, however, remains the same.  
; SIDE EFFECTS:
;       The .DBF and .dbx files are opened using unit numbers obtained by
;       GET_LUN.  Descriptions of the files are placed in the common block
;       DB_COM.
;
; PROCEDURES CALLED:
;       DBCLOSE, DB_INFO(), SELECT_W, ZPARCHECK
; HISTORY:
;       For IDL Version 2  W. Landsman May 1990 -- Will require further 
;           modfication once SCREEN_SELECT is working
;       Modified to work under Unix, D. Neill, ACC, Feb 1991.
;       UNAVAIL keyword added.  M. Greason, Hughes STX, Feb 1993.
;       William Thompson, GSFC/CDS (ARC), 1 June 1994
;               Added support for external (IEEE) representation.
;       William Thompson, GSFC, 3 November 1994
;                       Modified to allow ZDBASE to be a path string.
;       8/29/95 JKF/ACC - forces lowercase for input database names.
;       W. Landsman, Use CATCH to catch errors    July, 1997
;       W. Landsman Use vector call to FDECOMP, STRSPLIT()    Sep 2006
;       W. Landsman Remove obsolete keywords to OPEN   Sep 2006
;       Replace SCREEN_SELECT with SELECT_W, remove IEEE_TO_HOST  WL  Jan 2009
;       Fix typos in BYTEORDER introduced Jan 2009 G. Scandariato/W.L.Feb. 2009
;
;-
;
;------------------------------------------------------------------------
On_error,2
;
; data base common block
;
common db_com,QDB,QITEMS,QDBREC
;
; QDB(*,i) contains the following for each data base opened
;
;       bytes
;         0-18   data base name character*19
;         19-79  data base title character*61
;         80-81  number of items (integer*2)
;         82-83  record length of DBF file (integer*2)
;         84-87  number of entries in file (integer*4)
;         88-89  position of first item for this file in QITEMS (I*2)
;         90-91  position of last item for this file (I*2)
;         92-95  Last Sequence number used (item=SEQNUM) (I*4)
;         96     Unit number of .DBF file
;         97     Unit number of .dbx file (0 if none exists)
;         98-99  Index number of item pointing to this file (0 for first db)
;         100-103 Number of entries with space allocated
;         104    Update flag (0 open for read only, 1 open for update)
;         119    Equals 1 if external data representation (IEEE) is used
;
;  QITEMS(*,i) contains decription of item number i with following
;  byte assignments:
;
;       0-19    item name (character*20)
;       20-21   IDL data type (integer*2)
;       22-23   Number of values for item (1 for scalar) (integer*2)
;       24-25   Starting byte position in original DBF record (integer*2)
;       26-27   Number of bytes per data value (integer*2)
;       28      Index type
;       29-97   Item description
;       98-99   print format field length
;       100     flag (1 if this items points to a data base)
;       101-119 Data base this item points to
;       120-125 Print format
;       126-170 Print headers
;       171-172 Starting byte in record returned by DBRD
;       173-174 Data base number in QDB
;       175-176 Data base number this item points to
;       177-178 Item number within the specific data base
;
;-------------------------------------------------------------------------
;
;
; check for valid input parameters
;
if N_params() lt 1 then name=''
if N_params() lt 2 then update=0
 catch, error_status
 if error_status NE 0 then begin 
       print,!ERR_STRING
       return
  endif

zparcheck,'DBOPEN',name,1,7,[0,1],'Data base name[s]'
zparcheck,'DBOPEN',update,2,[1,2,3,4,5],0,'Update flag'
;
; check privilege
;
if update and (!priv lt 2) then  $
        message,'!PRIV must be 2 or greater to open with update'
;
; check UNAVAIL
;
unav_flg = arg_present(unavail) 
unavail = 0
totret = 1
;---------------------------------------------------------------------
;       PROCESS INPUT NAMES (CREATE STRING ARRAY)
;
; Process scalar name
;
s=size(name) & ndim=s[0]
if ndim eq 0 then begin
;
; process name=''
;
    if strtrim(name) EQ '' then begin
        names = list_with_path('*.dbh', 'ZDBASE', Count = N)
        if n EQ 0 then message, $
           'No database (.dbh) files found in ZDBASE or current directory'
        fdecomp,names,disk,dir,fnames,qual,ver
        
        select_w,fnames,isel,'db_titles', $
                'Select data base file to open',1
        fnames=fnames[intarr(1)+isel]
      end else $
;
; separate names into string array
;
        fnames = strlowcase( strsplit(name,',',/extract))
   end else begin
;
; name is already a string vector
;
    fnames=name
end
;
; if update, only one data base can be opened
;
if update then if N_elements(fnames) gt 1 then $
        message,'Only one file can be specified if mode is update'
;
;---------------------------------------------------------------
;
;       LOOP AND OPEN EACH DATA BASE
;
; close any data bases already open
;
dbclose
;
;
offset=0                ;byte offset in dbrd record for data base
tot_items=0             ;total number of items all opened data bases
get_lun,unit            ;get unit number to use for .dbh files
dbno=0                  ;present data base number
while dbno lt n_elements(fnames) do begin
    dbname=strtrim(fnames[dbno])
;
; process * if second in list  -----------------------
;
    if dbname eq '*' then begin         ;get data base names from pointers
        if dbno ne 1 then begin         ;* must be second data base
            message,'Invalid use of * specification',/continue
            goto,ABORT   
        endif
        pointers=qitems[100,*]          ;find pointer items
        good=where(pointers,n)
        if n eq 0 then goto,done        ;no pointers
        pnames=string(qitems[101:119,*]);file names for pointers
        fnames=[fnames[0],pnames[good]] ;new file list
        dbname=strtrim(fnames[1])       ;new second name
    end
;
; open .dbh file and read contents ------------------------
;
    dbhname = find_with_def(dbname+'.dbh', 'ZDBASE')
    openr,unit,dbhname,ERROR=err     

    if err NE 0 then begin
        if unav_flg EQ 0 then begin
                message,'Error opening .dbh file '+ dbname,/CONTINUE
                print,!SYSERR_STRING
        endif else totret = 0
        unavail = 1
        goto, ABORT 
    end
    db=bytarr(120)
    readu,unit,db
    external = db[119] eq 1     ;Is external data rep. being used?
    totbytes=fix(db,82,1) & totbytes=totbytes[0]
    nitems=fix(db,80,1) & nitems=nitems[0] ;number of items or fields in file
    if external then begin
        byteorder, totbytes, /NTOHS  &  db[82] = byte(totbytes,0,2)
        byteorder, nitems,/NTOHS   &  db[80] = byte(nitems,0,2)
    endif
    items=bytarr(200,nitems)
    readu,unit,items
    close,unit
    if external then begin
        tmp = fix(items[20:27,*],0,4,nitems)
        byteorder,tmp, /ntohs
        items[20,0] = byte(tmp,0,8,nitems)
;
        tmp = fix(items[98:99,*],0,1,nitems)
        byteorder,tmp,/NTOHS
        items[98,0] = byte(tmp,0,2,nitems)
;
        tmp = fix(items[171:178,*],0,4,nitems)
        byteorder,tmp,/NTOHS
        items[171,0] = byte(tmp,0,8,nitems)
    endif
;
; add computed information to items ---------------------------
;
    sbyte=fix(items[24:25,*],0,nitems)+offset
    for i=0,nitems-1 do begin
        items[171,i]=byte(sbyte[i],0,2) ;starting byte in DBRD record
        items[173,i]=byte(dbno,0,2)     ;data base number
        items[177,i]=byte(i,0,2)        ;item number
    end
    offset=offset+totbytes
;
; open .dbf file ---------------------------------
;
    get_lun,unitdbf
    dbf_file = find_with_def(dbname+'.dbf', 'ZDBASE')
    if update eq 1 then $
         openu,unitdbf,dbf_file else $ 
         openr,unitdbf,dbf_file,error=err
    if err ne 0 then begin
        message,'Error opening '+dbname+'.dbf',/continue
        free_lun,unitdbf
        goto,abort
    end
    p=assoc(unitdbf,lonarr(2))
    head = p[0]
    if external then byteorder, head, /NTOHL
    db[96]=unitdbf                      ;unit number of .dbf file
    db[84]=byte(head[0],0,4)            ;number of entries
    db[92]=byte(head[1],0,4)            ;last seqnum used
    db[88]=byte(tot_items,0,2)          ;starting item number for this db
    tot_items=tot_items+nitems          ;new total number of items
    db[90]=byte(tot_items-1,0,2)        ;last item number for this db
    db[104]=update                      ;opened for update
;
; open index file if necessary -----------------------------
;
    index=where(items[28,*] gt 0,nindex)        ;indexed items
    if nindex gt 0 then begin           ;need to open index file.
        get_lun,unitind
        dbx_file = find_with_def(dbname+'.dbx', 'ZDBASE')
        if update gt 0 then $
                  openu,unitind,dbx_file,error=err $
           else openr,unitind,dbx_file,error=err
        if err ne 0 then begin
                message,'Error opening index file for '+dbname,/continue
                free_lun,unitdbf
                free_lun,unitind
                goto,abort
        endif
        db[97]=unitind                  ;unit number for index file
    end
;
; add to common block ---------------------
;
    if dbno eq 0 then begin
        qdb=db
        qitems=items
      end else begin
        old=qdb
        qdb=bytarr(120,dbno+1)
        qdb[0,0] = old
        qdb[0,dbno] = db
        old=qitems
        qitems=bytarr(200,tot_items)
        qitems[0,0] = old
        qitems[0,tot_items-nitems] = items
    end
;
    dbno=dbno+1
end; loop on data bases
done: free_lun,unit
;--------------------------------------------------------------------
;               LINK PROCESSING
;
; determine linkages between data bases
;
numdb = N_elements(fnames)
if numdb gt 1 then begin
    pnames=strupcase(qitems[101:119,*])
    for i=1,numdb-1 do begin
        dbname=strupcase(qdb[0:18,i])   ;name of the data base
        for j=0,tot_items-1 do if pnames[j] eq dbname then goto,found
;
; if we made it here we can not link the file -----------
;
        message,'Unable to link data base file '+dbname,/continue
        goto,abort
;
; found linkage item ------------------------------------
;
found:
        item_number=j           ;number of item supplying link
        item_db=fix(qitems[173:174,item_number],0,1) & item_db=item_db[0]
        if item_db ge i then begin
                message,'Unable to link data base '+dbname + $
                        'to previous data base.',/continue
                print,' Possible incorrect ordering of input data bases'
                goto,abort
        endif
        qitems[175,item_number]=byte(i,0,2)     ;data base number pointed to
        qdb[98,i]=byte(item_number,0,2)         ;item number pointing to this db
nextdb:
    endfor
endif
;
; create an assoc variable for the first db
;
unit=db_info('unit_dbf',0)
len=db_info('length',0)
qdbrec=assoc(unit,bytarr(len))
;----------------------------------------------------------------------------
; done
;
return
;
; abort
;
abort:
dbclose                         ;close any open data bases
free_lun,unit
if (totret NE 0) then retall else return
end