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FUNCTION FXPOSIT, XFILE, EXT_NO, readonly=readonly, COMPRESS=COMPRESS, $ |
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SILENT = Silent, EXTNUM = extnum, ERRMSG= ERRMSG, LUNIT = lunit |
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;+ |
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; NAME: |
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; FXPOSIT |
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; PURPOSE: |
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; Return the unit number of a FITS file positioned at specified extension |
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; EXPLANATION: |
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; The FITS file will be ready to be read at the beginning of the |
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; specified extension. Exither an extension number or extension name |
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; can be specified. Called by headfits.pro, mrdfits.pro, readfits.pro |
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; |
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; CALLING SEQUENCE: |
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; unit=FXPOSIT(FILE, EXT_NO_OR_NAME, /READONLY, COMPRESS=program, |
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; ERRMSG= , EXTNUM= , UNIT=, /SILENT) |
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; |
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; INPUT PARAMETERS: |
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; FILE = FITS file name, scalar string |
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; EXT_NO_OR_NAME = Either the extension to be moved to (scalar |
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; nonnegative integer) or the name of the extension to read |
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; (scalar string) |
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; |
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; RETURNS: |
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; Unit number of file or -1 if an error is detected. |
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; |
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; OPTIONAL INPUT KEYWORD PARAMETER: |
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; /READONLY - If this keyword is set and non-zero, then OPENR rather |
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; than OPENU will be used to open the FITS file. |
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; COMPRESS - If this keyword is set and non-zero, then then treat |
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; the file as compressed. If 1 assume a gzipped file. |
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; and use IDLs internal decompression facility. For Unix |
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; compressed or bzip2 compressed files spawn off a process to |
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; decompress and use its output as the FITS stream. If the |
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; keyword is not 1, then use its value as a string giving the |
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; command needed for decompression. |
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; LUNIT - Integer giving the file unit number. Use this keyword if |
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; you want to override the default use of GET_LUN to obtain |
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; a unit number. |
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; /SILENT If set, then suppress any messages about invalid characters |
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; in the FITS file. |
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; |
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; OPTIONAL OUTPUT KEYWORDS: |
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; EXTNUM - Nonnegative integer give the extension number actually read |
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; Useful only if the extension was specified by name. |
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; ERRMSG = If this keyword is present, then any error messages will be |
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; returned to the user in this parameter rather than |
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; depending on the MESSAGE routine in IDL. If no errors are |
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; encountered, then a null string is returned. |
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; SIDE EFFECTS: |
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; Opens and returns a file unit. |
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; PROCEDURE: |
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; Open the appropriate file, or spawn a command and intercept |
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; the output. |
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; Call FXMOVE to get to the appropriate extension. |
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; PROCEDURE CALLS: |
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; FXMOVE() |
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; MODIFICATION HISTORY: |
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; Derived from William Thompson's FXFINDEND routine. |
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; Modified by T.McGlynn, 5-October-1994. |
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; Modified by T.McGlynn, 25-Feb-1995 to handle compressed |
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; files. Pipes cannot be accessed using FXHREAD so |
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; MRD_HREAD was written. |
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; W. Landsman 23-Apr-1997 Force the /bin/sh shell when uncompressing |
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; T. McGlynn 03-June-1999 Use /noshell option to get rid of processes left by spawn. |
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; Use findfile to retain ability to use wildcards |
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; W. Landsman 03-Aug-1999 Use EXPAND_TILDE under Unix to find file |
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; T. McGlynn 04-Apr-2000 Put reading code into FXMOVE, |
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; additional support for compression from D.Palmer. |
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; W. Landsman/D.Zarro 04-Jul-2000 Added test for !VERSION.OS EQ 'Win32' (WinNT) |
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; W. Landsman 12-Dec-2000 Added /SILENT keyword |
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; W. Landsman April 2002 Use FILE_SEARCH for V5.5 or later |
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; W. Landsman Feb 2004 Assume since V5.3 (OPENR,/COMPRESS available) |
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; W. Landsman,W. Thompson, 2-Mar-2004, Add support for BZIP2 |
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; W. Landsman Don't leave open file if an error occurs |
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; W. Landsman Sep 2004 Treat FTZ extension as gzip compressed |
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; W. Landsman Feb 2006 Removed leading spaces (prior to V5.5) |
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; W. Landsman Nov 2006 Allow specification of extension name |
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; Added EXTNUM, ERRMSG keywords |
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; W. Landsman/N.Piskunov Dec 2007 Added LUNIT keyword |
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;- |
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; |
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ON_ERROR,2 |
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compile_opt idl2 |
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; |
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; Check the number of parameters. |
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; |
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IF N_PARAMS() LT 2 THEN BEGIN |
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PRINT,'SYNTAX: UNIT = FXPOSIT(FILE, EXT_NO, /Readonly,' + $ |
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'ERRMSG= , /SILENT, compress=prog, LUNIT = lunit)' |
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RETURN,-1 |
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ENDIF |
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PRINTERR = NOT ARG_PRESENT(ERRMSG) |
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ERRMSG = '' |
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|
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FILE = FILE_SEARCH(XFILE, COUNT=COUNT) |
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|
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IF COUNT EQ 0 THEN BEGIN |
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ERRMSG = 'Specified FITS File not found ' |
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IF PRINTERR THEN MESSAGE,ERRMSG,/CON |
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RETURN, -1 ; Don't print anything out, just report an error |
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ENDIF |
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|
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FILE = FILE[0] |
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; |
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; Check if logical unit number is specified explicitly. |
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; |
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IF KEYWORD_SET(LUNIT) THEN BEGIN |
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UNIT=LUNIT |
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GLUN = 0 |
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ENDIF ELSE BEGIN |
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UNIT = -1 |
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GLUN = 1 |
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ENDELSE |
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; |
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; Check if this is a compressed file. |
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; |
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UCMPRS = ' ' |
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IF KEYWORD_SET(compress) THEN BEGIN |
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IF strcompress(string(compress),/remo) eq '1' THEN BEGIN |
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compress = 'gunzip' |
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ENDIF |
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UCMPRS = compress; |
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ENDIF ELSE BEGIN |
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|
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LEN = STRLEN(FILE) |
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IF LEN GT 3 THEN $ |
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TAIL = STRLOWCASE(STRMID(FILE, LEN-3, 3)) $ |
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ELSE TAIL = ' ' |
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|
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IF STRMID(TAIL,1,2) EQ '.z' THEN $ |
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UCMPRS = 'uncompress' $ |
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ELSE IF TAIL EQ '.gz' or tail EQ 'ftz' THEN $ |
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UCMPRS = 'gunzip' $ |
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ELSE IF TAIL EQ 'bz2' THEN $ |
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UCMPRS = 'bunzip2' |
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|
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ENDELSE |
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|
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; Handle compressed files. |
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|
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IF UCMPRS EQ 'gunzip' THEN BEGIN |
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|
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IF KEYWORD_SET(READONLY) THEN BEGIN |
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OPENR, UNIT, FILE, /COMPRESS, GET_LUN=glun, ERROR = ERROR |
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ENDIF ELSE BEGIN |
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OPENU, UNIT, FILE, /COMPRESS, GET_LUN=glun, ERROR = ERROR |
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ENDELSE |
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|
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ENDIF ELSE IF UCMPRS NE ' ' THEN BEGIN |
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|
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IF (!VERSION.OS_FAMILY EQ 'unix') THEN BEGIN |
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SPAWN, [UCMPRS,'-c',FILE], UNIT=UNIT, /NOSHELL |
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ENDIF ELSE BEGIN |
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PRINT, 'MRDFITS: Only Unix IDL supports piped spawns' |
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PRINT, ' File must be uncompressed manually' |
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RETURN, -1 |
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ENDELSE |
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|
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ENDIF ELSE BEGIN |
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; |
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; Go to the start of the file. |
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; |
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IF KEYWORD_SET(READONLY) THEN BEGIN |
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OPENR, UNIT, FILE, GET_LUN=glun, ERROR = ERROR |
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ENDIF ELSE BEGIN |
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OPENU, UNIT, FILE, GET_LUN=glun, ERROR = ERROR |
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ENDELSE |
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|
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IF ERROR NE 0 THEN BEGIN |
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IF PRINTERR THEN PRINT,!ERROR_STATE.MSG ELSE $ |
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ERRMSG = !ERROR_STATE.MSG |
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RETURN,-1 |
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ENDIF |
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ENDELSE |
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|
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IF SIZE(EXT_NO,/TNAME) NE 'STRING' THEN $ |
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IF EXT_NO LE 0 THEN RETURN, UNIT |
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|
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STAT = FXMOVE(UNIT, EXT_NO, SILENT = Silent, EXT_NO = extnum, $ |
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ERRMSG=ERRMSG) |
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IF STAT LT 0 THEN BEGIN |
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IF(NOT KEYWORD_SET(LUNIT)) THEN FREE_LUN, UNIT |
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RETURN, STAT |
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ENDIF ELSE RETURN, UNIT |
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END |
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|
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