xermsg.F

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*DECK XERMSG
      SUBROUTINE xermsg (LIBRAR, SUBROU, MESSG, NERR, LEVEL)
      IMPLICIT NONE
C***BEGIN PROLOGUE  XERMSG
C***PURPOSE  Process error messages for SLATEC and other libraries.
C***LIBRARY   SLATEC (XERROR)
C***CATEGORY  R3C
C***TYPE      ALL (XERMSG-A)
C***KEYWORDS  ERROR MESSAGE, XERROR
C***AUTHOR  Fong, Kirby, (NMFECC at LLNL)
C***DESCRIPTION
C
C   XERMSG processes a diagnostic message in a manner determined by the
C   value of LEVEL and the current value of the library error control
C   flag, KONTRL.  See subroutine XSETF for details.
C
C    LIBRAR   A character constant (or character variable) with the name
C             of the library.  This will be 'SLATEC' for the SLATEC
C             Common Math Library.  The error handling package is
C             general enough to be used by many libraries
C             simultaneously, so it is desirable for the routine that
C             detects and reports an error to identify the library name
C             as well as the routine name.
C
C    SUBROU   A character constant (or character variable) with the name
C             of the routine that detected the error.  Usually it is the
C             name of the routine that is calling XERMSG.  There are
C             some instances where a user callable library routine calls
C             lower level subsidiary routines where the error is
C             detected.  In such cases it may be more informative to
C             supply the name of the routine the user called rather than
C             the name of the subsidiary routine that detected the
C             error.
C
C    MESSG    A character constant (or character variable) with the text
C             of the error or warning message.  In the example below,
C             the message is a character constant that contains a
C             generic message.
C
C                   CALL XERMSG ('SLATEC', 'MMPY',
C                  *'THE ORDER OF THE MATRIX EXCEEDS THE ROW DIMENSION',
C                  *3, 1)
C
C             It is possible (and is sometimes desirable) to generate a
C             specific message--e.g., one that contains actual numeric
C             values.  Specific numeric values can be converted into
C             character strings using formatted WRITE statements into
C             character variables.  This is called standard Fortran
C             internal file I/O and is exemplified in the first three
C             lines of the following example.  You can also catenate
C             substrings of characters to construct the error message.
C             Here is an example showing the use of both writing to
C             an internal file and catenating character strings.
C
C                   CHARACTER*5 CHARN, CHARL
C                   WRITE (CHARN,10) N
C                   WRITE (CHARL,10) LDA
C                10 FORMAT(I5)
C                   CALL XERMSG ('SLATEC', 'MMPY', 'THE ORDER'//CHARN//
C                  *   ' OF THE MATRIX EXCEEDS ITS ROW DIMENSION OF'//
C                  *   CHARL, 3, 1)
C
C             There are two subtleties worth mentioning.  One is that
C             the // for character catenation is used to construct the
C             error message so that no single character constant is
C             continued to the next line.  This avoids confusion as to
C             whether there are trailing blanks at the end of the line.
C             The second is that by catenating the parts of the message
C             as an actual argument rather than encoding the entire
C             message into one large character variable, we avoid
C             having to know how long the message will be in order to
C             declare an adequate length for that large character
C             variable.  XERMSG calls XERPRN to print the message using
C             multiple lines if necessary.  If the message is very long,
C             XERPRN will break it into pieces of 72 characters (as
C             requested by XERMSG) for printing on multiple lines.
C             Also, XERMSG asks XERPRN to prefix each line with ' *  '
C             so that the total line length could be 76 characters.
C             Note also that XERPRN scans the error message backwards
C             to ignore trailing blanks.  Another feature is that
C             the substring '$$' is treated as a new line sentinel
C             by XERPRN.  If you want to construct a multiline
C             message without having to count out multiples of 72
C             characters, just use '$$' as a separator.  '$$'
C             obviously must occur within 72 characters of the
C             start of each line to have its intended effect since
C             XERPRN is asked to wrap around at 72 characters in
C             addition to looking for '$$'.
C
C    NERR     An integer value that is chosen by the library routine's
C             author.  It must be in the range -99 to 999 (three
C             printable digits).  Each distinct error should have its
C             own error number.  These error numbers should be described
C             in the machine readable documentation for the routine.
C             The error numbers need be unique only within each routine,
C             so it is reasonable for each routine to start enumerating
C             errors from 1 and proceeding to the next integer.
C
C    LEVEL    An integer value in the range 0 to 2 that indicates the
C             level (severity) of the error.  Their meanings are
C
C            -1  A warning message.  This is used if it is not clear
C                that there really is an error, but the user's attention
C                may be needed.  An attempt is made to only print this
C                message once.
C
C             0  A warning message.  This is used if it is not clear
C                that there really is an error, but the user's attention
C                may be needed.
C
C             1  A recoverable error.  This is used even if the error is
C                so serious that the routine cannot return any useful
C                answer.  If the user has told the error package to
C                return after recoverable errors, then XERMSG will
C                return to the Library routine which can then return to
C                the user's routine.  The user may also permit the error
C                package to terminate the program upon encountering a
C                recoverable error.
C
C             2  A fatal error.  XERMSG will not return to its caller
C                after it receives a fatal error.  This level should
C                hardly ever be used; it is much better to allow the
C                user a chance to recover.  An example of one of the few
C                cases in which it is permissible to declare a level 2
C                error is a reverse communication Library routine that
C                is likely to be called repeatedly until it integrates
C                across some interval.  If there is a serious error in
C                the input such that another step cannot be taken and
C                the Library routine is called again without the input
C                error having been corrected by the caller, the Library
C                routine will probably be called forever with improper
C                input.  In this case, it is reasonable to declare the
C                error to be fatal.
C
C    Each of the arguments to XERMSG is input; none will be modified by
C    XERMSG.  A routine may make multiple calls to XERMSG with warning
C    level messages; however, after a call to XERMSG with a recoverable
C    error, the routine should return to the user.  Do not try to call
C    XERMSG with a second recoverable error after the first recoverable
C    error because the error package saves the error number.  The user
C    can retrieve this error number by calling another entry point in
C    the error handling package and then clear the error number when
C    recovering from the error.  Calling XERMSG in succession causes the
C    old error number to be overwritten by the latest error number.
C    This is considered harmless for error numbers associated with
C    warning messages but must not be done for error numbers of serious
C    errors.  After a call to XERMSG with a recoverable error, the user
C    must be given a chance to call NUMXER or XERCLR to retrieve or
C    clear the error number.
C***REFERENCES  R. E. Jones and D. K. Kahaner, XERROR, the SLATEC
C                 Error-handling Package, SAND82-0800, Sandia
C                 Laboratories, 1982.
C***ROUTINES CALLED  FDUMP, J4SAVE, XERCNT, XERHLT, XERPRN, XERSVE
C***REVISION HISTORY  (YYMMDD)
C   880101  DATE WRITTEN
C   880621  REVISED AS DIRECTED AT SLATEC CML MEETING OF FEBRUARY 1988.
C           THERE ARE TWO BASIC CHANGES.
C           1.  A NEW ROUTINE, XERPRN, IS USED INSTEAD OF XERPRT TO
C               PRINT MESSAGES.  THIS ROUTINE WILL BREAK LONG MESSAGES
C               INTO PIECES FOR PRINTING ON MULTIPLE LINES.  '$$' IS
C               ACCEPTED AS A NEW LINE SENTINEL.  A PREFIX CAN BE
C               ADDED TO EACH LINE TO BE PRINTED.  XERMSG USES EITHER
C               ' ***' OR ' *  ' AND LONG MESSAGES ARE BROKEN EVERY
C               72 CHARACTERS (AT MOST) SO THAT THE MAXIMUM LINE
C               LENGTH OUTPUT CAN NOW BE AS GREAT AS 76.
C           2.  THE TEXT OF ALL MESSAGES IS NOW IN UPPER CASE SINCE THE
C               FORTRAN STANDARD DOCUMENT DOES NOT ADMIT THE EXISTENCE
C               OF LOWER CASE.
C   880708  REVISED AFTER THE SLATEC CML MEETING OF JUNE 29 AND 30.
C           THE PRINCIPAL CHANGES ARE
C           1.  CLARIFY COMMENTS IN THE PROLOGUES
C           2.  RENAME XRPRNT TO XERPRN
C           3.  REWORK HANDLING OF '$$' IN XERPRN TO HANDLE BLANK LINES
C               SIMILAR TO THE WAY FORMAT STATEMENTS HANDLE THE /
C               CHARACTER FOR NEW RECORDS.
C   890706  REVISED WITH THE HELP OF FRED FRITSCH AND REG CLEMENS TO
C           CLEAN UP THE CODING.
C   890721  REVISED TO USE NEW FEATURE IN XERPRN TO COUNT CHARACTERS IN
C           PREFIX.
C   891013  REVISED TO CORRECT COMMENTS.
C   891214  Prologue converted to Version 4.0 format.  (WRB)
C   900510  Changed test on NERR to be -9999999 < NERR < 99999999, but
C           NERR .ne. 0, and on LEVEL to be -2 < LEVEL < 3.  Added
C           LEVEL=-1 logic, changed calls to XERSAV to XERSVE, and
C           XERCTL to XERCNT.  (RWC)
C   920501  Reformatted the REFERENCES section.  (WRB)
C***END PROLOGUE  XERMSG
      CHARACTER*(*) LIBRAR, SUBROU, MESSG
      CHARACTER*8 XLIBR, XSUBR
      CHARACTER*72  TEMP
      CHARACTER*20  LFIRST
      INTEGER NERR, LEVEL, LKNTRL
      INTEGER J4SAVE, MAXMES, KDUMMY, I, KOUNT, LERR, LLEVEL
      INTEGER MKNTRL, LTEMP
C***FIRST EXECUTABLE STATEMENT  XERMSG
      lkntrl = j4save(2, 0, .false.)
      maxmes = j4save(4, 0, .false.)
C
C       LKNTRL IS A LOCAL COPY OF THE CONTROL FLAG KONTRL.
C       MAXMES IS THE MAXIMUM NUMBER OF TIMES ANY PARTICULAR MESSAGE
C          SHOULD BE PRINTED.
C
C       WE PRINT A FATAL ERROR MESSAGE AND TERMINATE FOR AN ERROR IN
C          CALLING XERMSG.  THE ERROR NUMBER SHOULD BE POSITIVE,
C          AND THE LEVEL SHOULD BE BETWEEN 0 AND 2.
C
      IF (nerr.LT.-9999999 .OR. nerr.GT.99999999 .OR. nerr.EQ.0 .OR.
     *   level.LT.-1 .OR. level.GT.2) THEN
         CALL xerprn (' ***', -1, 'FATAL ERROR IN...$$ ' //
     *      'XERMSG -- INVALID ERROR NUMBER OR LEVEL$$ '//
     *      'JOB ABORT DUE TO FATAL ERROR.', 72)
         CALL xersve (' ', ' ', ' ', 0, 0, 0, kdummy)
         CALL xerhlt (' ***XERMSG -- INVALID INPUT')
         RETURN
      ENDIF
C
C       RECORD THE MESSAGE.
C
      i = j4save(1, nerr, .true.)
      CALL xersve (librar, subrou, messg, 1, nerr, level, kount)
C
C       HANDLE PRINT-ONCE WARNING MESSAGES.
C
      IF (level.EQ.-1 .AND. kount.GT.1) RETURN
C
C       ALLOW TEMPORARY USER OVERRIDE OF THE CONTROL FLAG.
C
      xlibr  = librar
      xsubr  = subrou
      lfirst = messg
      lerr   = nerr
      llevel = level
      CALL xercnt (xlibr, xsubr, lfirst, lerr, llevel, lkntrl)
C
      lkntrl = max(-2, min(2,lkntrl))
      mkntrl = abs(lkntrl)
C
C       SKIP PRINTING IF THE CONTROL FLAG VALUE AS RESET IN XERCNT IS
C       ZERO AND THE ERROR IS NOT FATAL.
C
      IF (level.LT.2 .AND. lkntrl.EQ.0) GO TO 30
      IF (level.EQ.0 .AND. kount.GT.maxmes) GO TO 30
      IF (level.EQ.1 .AND. kount.GT.maxmes .AND. mkntrl.EQ.1) GO TO 30
      IF (level.EQ.2 .AND. kount.GT.max(1,maxmes)) GO TO 30
C
C       ANNOUNCE THE NAMES OF THE LIBRARY AND SUBROUTINE BY BUILDING A
C       MESSAGE IN CHARACTER VARIABLE TEMP (NOT EXCEEDING 66 CHARACTERS)
C       AND SENDING IT OUT VIA XERPRN.  PRINT ONLY IF CONTROL FLAG
C       IS NOT ZERO.
C
      IF (lkntrl .NE. 0) THEN
         temp(1:21) = 'MESSAGE FROM ROUTINE '
         i = min(len(subrou), 16)
         temp(22:21+i) = subrou(1:i)
         temp(22+i:33+i) = ' IN LIBRARY '
         ltemp = 33 + i
         i = min(len(librar), 16)
         temp(ltemp+1:ltemp+i) = librar(1:i)
         temp(ltemp+i+1:ltemp+i+1) = '.'
         ltemp = ltemp + i + 1
         CALL xerprn (' ***', -1, temp(1:ltemp), 72)
      ENDIF
C
C       IF LKNTRL IS POSITIVE, PRINT AN INTRODUCTORY LINE BEFORE
C       PRINTING THE MESSAGE.  THE INTRODUCTORY LINE TELLS THE CHOICE
C       FROM EACH OF THE FOLLOWING THREE OPTIONS.
C       1.  LEVEL OF THE MESSAGE
C              'INFORMATIVE MESSAGE'
C              'POTENTIALLY RECOVERABLE ERROR'
C              'FATAL ERROR'
C       2.  WHETHER CONTROL FLAG WILL ALLOW PROGRAM TO CONTINUE
C              'PROG CONTINUES'
C              'PROG ABORTED'
C       3.  WHETHER OR NOT A TRACEBACK WAS REQUESTED.  (THE TRACEBACK
C           MAY NOT BE IMPLEMENTED AT SOME SITES, SO THIS ONLY TELLS
C           WHAT WAS REQUESTED, NOT WHAT WAS DELIVERED.)
C              'TRACEBACK REQUESTED'
C              'TRACEBACK NOT REQUESTED'
C       NOTICE THAT THE LINE INCLUDING FOUR PREFIX CHARACTERS WILL NOT
C       EXCEED 74 CHARACTERS.
C       WE SKIP THE NEXT BLOCK IF THE INTRODUCTORY LINE IS NOT NEEDED.
C
      IF (lkntrl .GT. 0) THEN
C
C       THE FIRST PART OF THE MESSAGE TELLS ABOUT THE LEVEL.
C
         IF (level .LE. 0) THEN
            temp(1:20) = 'INFORMATIVE MESSAGE,'
            ltemp = 20
         ELSEIF (level .EQ. 1) THEN
            temp(1:30) = 'POTENTIALLY RECOVERABLE ERROR,'
            ltemp = 30
         ELSE
            temp(1:12) = 'FATAL ERROR,'
            ltemp = 12
         ENDIF
C
C       THEN WHETHER THE PROGRAM WILL CONTINUE.
C
         IF ((mkntrl.EQ.2 .AND. level.GE.1) .OR.
     *       (mkntrl.EQ.1 .AND. level.EQ.2)) THEN
            temp(ltemp+1:ltemp+14) = ' PROG ABORTED,'
            ltemp = ltemp + 14
         ELSE
            temp(ltemp+1:ltemp+16) = ' PROG CONTINUES,'
            ltemp = ltemp + 16
         ENDIF
C
C       FINALLY TELL WHETHER THERE SHOULD BE A TRACEBACK.
C
         IF (lkntrl .GT. 0) THEN
            temp(ltemp+1:ltemp+20) = ' TRACEBACK REQUESTED'
            ltemp = ltemp + 20
         ELSE
            temp(ltemp+1:ltemp+24) = ' TRACEBACK NOT REQUESTED'
            ltemp = ltemp + 24
         ENDIF
         CALL xerprn (' ***', -1, temp(1:ltemp), 72)
      ENDIF
C
C       NOW SEND OUT THE MESSAGE.
C
      CALL xerprn (' *  ', -1, messg, 72)
C
C       IF LKNTRL IS POSITIVE, WRITE THE ERROR NUMBER AND REQUEST A
C          TRACEBACK.
C
      IF (lkntrl .GT. 0) THEN
         WRITE (temp, '(''ERROR NUMBER = '', I8)') nerr
         DO 10 i=16,22
            IF (temp(i:i) .NE. ' ') GO TO 20
   10    CONTINUE
C
   20    CALL xerprn (' *  ', -1, temp(1:15) // temp(i:23), 72)
         CALL fdump
      ENDIF
C
C       IF LKNTRL IS NOT ZERO, PRINT A BLANK LINE AND AN END OF MESSAGE.
C
      IF (lkntrl .NE. 0) THEN
         CALL xerprn (' *  ', -1, ' ', 72)
         CALL xerprn (' ***', -1, 'END OF MESSAGE', 72)
         CALL xerprn ('    ',  0, ' ', 72)
      ENDIF
C
C       IF THE ERROR IS NOT FATAL OR THE ERROR IS RECOVERABLE AND THE
C       CONTROL FLAG IS SET FOR RECOVERY, THEN RETURN.
C
   30 IF (level.LE.0 .OR. (level.EQ.1 .AND. mkntrl.LE.1)) RETURN
C
C       THE PROGRAM WILL BE STOPPED DUE TO AN UNRECOVERED ERROR OR A
C       FATAL ERROR.  PRINT THE REASON FOR THE ABORT AND THE ERROR
C       SUMMARY IF THE CONTROL FLAG AND THE MAXIMUM ERROR COUNT PERMIT.
C
      IF (lkntrl.GT.0 .AND. kount.LT.max(1,maxmes)) THEN
         IF (level .EQ. 1) THEN
            CALL xerprn
     *         (' ***', -1, 'JOB ABORT DUE TO UNRECOVERED ERROR.', 72)
         ELSE
            CALL xerprn(' ***', -1, 'JOB ABORT DUE TO FATAL ERROR.', 72)
         ENDIF
         CALL xersve (' ', ' ', ' ', -1, 0, 0, kdummy)
         CALL xerhlt (' ')
      ELSE
         CALL xerhlt (messg)
      ENDIF
      RETURN
      END