subroutine event_display_get_event(ireturn_code)
c
c
c This routine fetches the next event from the event data file.
c The file is opened, read, and then deleted so that the DAQ will
c recognize that it's time to create a new file.
c
c
c George Gollin, g-gollin@uiuc.edu, 1999.
c
c return codes (only the last error is reported): 
c     0  if everything's fine, and we have good event data.
c     1  if we couldn't open the file
c     2  if we hit the end-of-file before encountering "EOD"
c     3  if we had a problem reading strip data header line
c     4  if we had a problem reading dem1 data header line
c     5  if we had a problem reading dem2 data header line
c     6  if we had a problem reading marebo data header line
c    16  if we had a problem reading module data header line
c     7  if we couldn't delete the event data file after reading it
c     8  if we tried reading detector data before encountering a header
c    -9  encountered bad strip detector data
c   -10  encountered bad run number, event number header line
c   -11  encountered bad dem1 detector data
c   -12  encountered bad dem2 detector data
c   -22  encountered bad module detector data
c   -13  found fewer lines of strip hit data than expected
c   -14  found fewer lines of dem1 hit data than expected
c   -15  found fewer lines of dem2 hit data than expected
c   -16  found fewer lines of marebo hit data than expected
c   -17  encountered bad marebo detector data
c   -26  found fewer lines of module hit data than expected
c   -27  encountered bad module detector data
c
c
c negative values for return code correspond to errors where the data line
c was ignored, but I continued to read from the file. positive values
c mean the event data was unusable.
c
c
#include "event_display.inc"
#include "event_display_data.inc"
c
c
c data format is described in the common blocks.
c
c NOTE: pixel detectors with z position set to zero will be ignored.
c
      logical first_time,file_exists
      logical now_reading_strips, now_reading_dem1, now_reading_dem2
      logical now_reading_demm, now_reading_demd
      logical hit_EOD, found_run
c
      character*132 line_buffer
      character*132 line
      character*80 text
c
ccc      integer*4 system
c
c
      data first_time  /.true./
c
      data lines_read_from_file /0/
      data ievents_read /0/
c
c
c *************************************************************************
c
c
c
c ******************* (initialize stuff)
c
c
      ireturn_code=0
c
      do iv=1,2
      do ipl=1,4
      num_strip_hits(iv,ipl)=0
      ifound_strip_hits(iv,ipl)=0
      end do
      end do
c
      num_strip_hits_total=0
      num_dem1_hits=0
      num_dem2_hits=0
      num_demm_hits=0
      num_demd_hits=0
      ifound_strip_hits_total=0
      ifound_dem1_hits=0
      ifound_dem2_hits=0
      ifound_demm_hits=0
      ifound_demd_hits=0
      lines_read_from_file=0
c
      phidem1=0.
      psidem1=0.
      thetadem1=0.
      xplane_z0(ipldem1)=0.
      yplane_z0(ipldem1)=0.
c
      phidem2=0.
      psidem2=0.
      thetadem2=0.
      xplane_z0(ipldem2)=0.
      yplane_z0(ipldem2)=0.
c
      phidemm=0.
      psidemm=0.
      thetademm=0.
      xplane_z0(ipldemm)=0.
      yplane_z0(ipldemm)=0.
c
      phidemd=0.
      psidemd=0.
      thetademd=0.
      xplane_z0(ipldemd)=0.
      yplane_z0(ipldemd)=0.
c
      z_read_dem1=0.
      z_read_dem2=0.
      z_read_demm=0.
      z_read_demd=0.
c
c the module has some of its detector cells shared by single readout
c channels.  keep track of that here, so I don't mess up my bookkeeping.
      number_shared_hits=0
c
c
c ******************* (open the file for single event's data)
c
c
c file may not be available as soon as I ask for it, do do this in a loop.
      do itry=0,10000
c
c
c ask...
      inquire(file=file_data(1:lenocc(file_data)), exist=file_exists)
c
c
c open it if available...
      if(file_exists) then 
c
c wait a second, in case file was being written at the time we detected it..
         call system('sleep 1')
c
c now open it:
         open(lun_data, file=file_data(1:lenocc(file_data)),
     .     status='old', iostat=io_err)
c
c
c if we've been waiting a while, offer a comment saying we got the file>
         if(itry .gt. 1000) then
            call event_display_write_message(
     .           '...FINALLY got the data file. I am SO patient!')
c
            else if(itry .gt. 200) then
            call event_display_write_message(
     .           '...OK, I got the data file. Sure took long enough!')
c
            else if(itry .gt. 50) then
            call event_display_write_message(
     .           '...I got the data file. Took a while, didn.t it?')
c
            else if(itry .gt. 5) then
            call event_display_write_message(
     .           '...Time to rock-n-roll.')
c
            end if
c
c
c jump to the next step if file opened OK:
         if(io_err .eq. 0) go to 100
c
c
c we're here if the file existed but didn't open properly.  write a message, 
c then fall through to the end of the loop, and try again. perhaps file was 
c open, and was still being created?
         call event_display_write_message(
     .        'couldn.t open event data file even though it existed!')
c
         else
c
c
c we are here when file didn't exist yet. If the user isn't bored, we  want 
c to wait a bit, then try again. If the user is fed up, they'll hit a button
c in a DAQ window which will cause the control file to be deleted. I'll
c take this as a sign that it is time to stop the display program. print a 
c message and update the x window occasionally while we wait.
         iambored=300
         if(mod(itry,iambored) .eq. 1) then
c
            call event_display_write_message(
     .           'waiting for data file... '//file_data)
c
            mode_synchronize=10
            call ixupdwi(mode_synchronize)
            end if
c
c
c if we've waited a bit longer, suggest how to kill the program:
         if(mod(itry,5*iambored) .eq. 4) then
c
            call event_display_write_message(
     .      '...the STOP button in this window is disabled while '
     .      //'waiting for data')
            call event_display_write_message(
     .      '   but you can kill the display from the DAQ window '
     .      //'or by ')
            call event_display_write_message(
     .      '   manually deleting '//file_control)
c
            mode_synchronize=10
            call ixupdwi(mode_synchronize)
            end if
c
c
c refresh the window if something has changed (for example, if the user 
c has resized the window out of boredom). the ...initialize_geometry routine
c is the one that can notice all this...
         call event_display_initialize_geometry
         if(something_changed) then
            call event_display_draw_detector
            call event_display_draw_hits
            call event_display_write_message('')
            mode_synchronize=10
            call ixupdwi(mode_synchronize)
            end if
c
         end if
c
c
c Has the DAQ deleted the control file? If so, time to stop.
        call event_display_control_exists(file_exists)
        if(.not. file_exists) then
c
c write message...
           call event_display_write_message(
     .          'Just received request from DAQ to stop. Good bye!')
c
c force an update of the screen...
            mode_synchronize=10
            call ixupdwi(mode_synchronize)
c
c pause a bit, so there's time for the user to read the message:
           call system('sleep 2')
c
c set the stop-now flag, then return:
           i_want_to_stop=.true.
c
           return
           end if
c
c
c wait for about 2 seconds, then go back to the start of the loop which looks
c for the data file.
      call system('sleep 1')
c
      end do
c
c
c ******************* (file wasn't there, so give up...)
c
c
c end up here if we were unable to open the file after many attempts.
c perhaps no run was in progress?
c
      call event_display_write_message(
     .  'I have failed miserably in numerous attempts '//
     .  'to open the data file '//file_data)
      ireturn_code=1
      return
c
c 
c ******************* (ready to start reading from the file)
c
c
 100  continue
c
c so far so good: now read the file. see comments in the common blocks for
c information about file format.
cc         call event_display_write_message(
cc     .        'opened data file '//file_data)
c
c
c ******************* (initialize type-of-detector data flags)
c
c
      now_reading_strips=.false.
      now_reading_dem1=.false.
      now_reading_dem2=.false.
      now_reading_demm=.false.
      now_reading_demd=.false.
      hit_EOD=.false.
      found_run=.false.
c
c
c ******************* (loop over reads starts here)
c

 200  continue
c
c
c read a line, treating it as text...
      read(lun_data, 1000, iostat=io_err) line_buffer
 1000 format(a)
c
c
c if this was written using list-directed (free form) output, there's probably
c a blank as the first character. protect against this by finding the first
c non-blank character. I'm having trouble with the cernlib routine,
c so do it myself.
c
      do i=1,132
      ifirst=i
      if(line_buffer(i:i) .ne. ' ') go to 25
      end do
c
 25   continue
c
      last=133-ifirst
      do i=1,132
      if(i .le. last) then
         line(i:i)=line_buffer(i+ifirst-1:i+ifirst-1)
         else
         line(i:i)=' '
         end if
      end do
c
      length=lenocc(line)
c      

c
c
c ******************* (check to see that we read a line OK)
c
c
c problems reading the line? if so, we probably hit the end of file
c without encountering the EOD line.
      if(io_err .ne. 0) then
c     
c         print *,
c     .        ' hit EOF before encountering last word in event??'
c         print *,' iostat returned was... ',io_err
c
         call event_display_write_message(
     .        ' hit EOF before encountering last word in event??')

c
         ireturn_code=2
         return
         endif
c
c
      lines_read_from_file=lines_read_from_file+1
c
c
c ******************* (start of data for a new detector?)
c
c
c see if the first few characters are "STRIPS" or "DEM1" or... to
c tell us what kind of data we're reading here. Treat marebo like dem2.
c
c start of strip data?
c
      if(     line(1:6) .eq. 'STRIPS' .or.
     .        line(1:6) .eq. 'Strips' .or.
     .        line(1:6) .eq. 'sTRIPS' .or.
     .        line(1:6) .eq. 'strips' ) then
c
         now_reading_strips=.true.
         now_reading_dem1=.false.
         now_reading_dem2=.false.
         now_reading_demm=.false.
         now_reading_demd=.false.
         hit_EOD=.false.
         found_run=.false.
c 
c remaining fields are length of strip data and z for each strip.
c
c CAREFUL!! the digit in "read(line(x:)..." must be 1 greater than the digit
c in the "if(line(1:y)..." statement above.
c the colon in the line(1:y)
         read(line(7:), *, iostat=io_err) num_strip_hits_total,
     .        (z_read_sirocco(ipl), ipl=1,8)
c
c check that it went OK.
         if(io_err .ne. 0) then
c
c            print *,
c     .           ' hit problem reading strip header record'
c            print *,' iostat returned was... ',io_err
c
            call event_display_write_message(
     .         ' ...problem reading strip header record')
c
            ireturn_code=3
            return
            end if
c
c
c load the z's:
         do ipl=1,4
         xplane_z0(ipl)=z_read_sirocco(ipl)
         yplane_z0(ipl)=z_read_sirocco(ipl+4)
         end do
c
c
c now get the next line of data:
         go to 200
c
c
c
c start of dem1 data?
c
      else if(line(1:4) .eq. 'DEM1' .or.
     .        line(1:4) .eq. 'Dem1' .or.
     .        line(1:4) .eq. 'dEM1' .or.
     .        line(1:4) .eq. 'dem1' ) then
c
         now_reading_strips=.false.
         now_reading_dem1=.true.
         now_reading_dem2=.false.
         now_reading_demm=.false.
         now_reading_demd=.false.
         hit_EOD=.false.
         found_run=.false.
c
c remaining fields are length of dem1 data, three angles, and z.
c
c CAREFUL!! the digit in "read(line(x:)..." must be 1 greater than the digit
c in the "if(line(1:y)..." statement above.
c the colon in the line(1:y)
         read(line(5:), *, iostat=io_err) num_dem1_hits_read,
     .        phi_read_dem1, psi_read_dem1, theta_read_dem1, z_read_dem1
     .        ,number_cols_read_dem1, number_rows_read_dem1
c
c check that it went OK.
         if(io_err .ne. 0) then
c
c            print *,
c     .           ' hit problem reading dem1 header record'
c            print *,' iostat returned was... ',io_err
c
            call event_display_write_message(
     .         ' ...problem reading dem1 header record')
c
            ireturn_code=4
            return
            end if
c
c
c load the angles and z's, but only if the z position is non-zero:
         if(z_read_dem1 .ne. 0.) then
            num_dem1_hits=num_dem1_hits_read
            phidem1=phi_read_dem1
            psidem1=psi_read_dem1
            thetadem1=theta_read_dem1
            xplane_z0(ipldem1)=z_read_dem1
            yplane_z0(ipldem1)=z_read_dem1
            number_cols_dem1=number_cols_read_dem1
            number_rows_dem1=number_rows_read_dem1
            end if
c
c
c
c now get the next line of data:
         go to 200
c
c
c
c start of dem2 data?
c
      else if(line(1:4) .eq. 'DEM2' .or.
     .        line(1:4) .eq. 'Dem2' .or.
     .        line(1:4) .eq. 'dEM2' .or.
     .        line(1:4) .eq. 'dem2' ) then
c
         now_reading_strips=.false.
         now_reading_dem1=.false.
         now_reading_dem2=.true.
         now_reading_demm=.false.
         now_reading_demd=.false.
         hit_EOD=.false.
         found_run=.false.
c
c remaining fields are length of dem2 data, three angles, and z.
c
c CAREFUL!! the digit in "read(line(x:)..." must be 1 greater than the digit
c in the "if(line(1:y)..." statement above.
c the colon in the line(1:y)
         read(line(5:), *, iostat=io_err) num_dem2_hits_read,
     .        phi_read_dem2, psi_read_dem2, theta_read_dem2, z_read_dem2
     .        ,number_cols_read_dem2, number_rows_read_dem2
c
c check that it went OK.
         if(io_err .ne. 0) then
c
c            print *,
c     .           ' hit problem reading dem2 header record'
c            print *,' iostat returned was... ',io_err
c
c
            call event_display_write_message(
     .         ' ...problem reading dem2 header record')
c
            ireturn_code=5
            return
            end if
c
c
c load the angles and z's, but only if the z position is non-zero:
         if(z_read_dem2 .ne. 0.) then
            num_dem2_hits=num_dem2_hits_read
            phidem2=phi_read_dem2
            psidem2=psi_read_dem2
            thetadem2=theta_read_dem2
            xplane_z0(ipldem2)=z_read_dem2
            yplane_z0(ipldem2)=z_read_dem2
            number_cols_dem2=number_cols_read_dem2
            number_rows_dem2=number_rows_read_dem2
            end if
c
c
c now get the next line of data:
         go to 200
c
c
c
c start of marebo data?
c
      else if(line(1:6) .eq. 'MAREBO' .or.
     .        line(1:6) .eq. 'Marebo' .or.
     .        line(1:6) .eq. 'mAREBO' .or.
     .        line(1:6) .eq. 'marebo'      ) then
c
c      else if(line(1:4) .eq. 'DEMM' .or.
c     .        line(1:4) .eq. 'Demm' .or.
c     .        line(1:4) .eq. 'dEMM' .or.
c     .        line(1:4) .eq. 'demm'      ) then
c
         now_reading_strips=.false.
         now_reading_dem1=.false.
         now_reading_dem2=.false.
         now_reading_demm=.true.
         now_reading_demd=.false.
         hit_EOD=.false.
         found_run=.false.
c
c remaining fields are length of marebo data, three angles, and z.
c I want to treat this like dem2 for the purposes of the display.
c
c CAREFUL!! the digit in "read(line(x:)..." must be 1 greater than the digit
c in the "if(line(1:y)..." statement above.
c the colon in the line(1:y)
ccccc         read(line(5:), *, iostat=io_err) num_demm_hits_read,
         read(line(7:), *, iostat=io_err) num_demm_hits_read,
     .        phi_read_demm, psi_read_demm, theta_read_demm,
     .        z_read_demm
     .        ,number_cols_read_demm, number_rows_read_demm
c
c check that it went OK.
         if(io_err .ne. 0) then
c
c            print *,
c     .           ' hit problem reading marebo header record'
c            print *,' iostat returned was... ',io_err
c
c
            call event_display_write_message(
     .         ' ...problem reading marebo header record')
c
            ireturn_code=6
            return
            end if
c
c
c load the angles and z's, but only if the z position is non-zero:
         if(z_read_demm .ne. 0.) then
            num_demm_hits=num_demm_hits_read
            phidemm=phi_read_demm
            psidemm=psi_read_demm
            thetademm=theta_read_demm
            xplane_z0(ipldemm)=z_read_demm
            yplane_z0(ipldemm)=z_read_demm
            number_cols_demm=number_cols_read_demm
            number_rows_demm=number_rows_read_demm
            end if
c
c
c now get the next line of data:
         go to 200
c
c
c
c start of module data?
c
      else if(line(1:4) .eq. 'MOD1' .or.
     .        line(1:4) .eq. 'Mod1' .or.
     .        line(1:4) .eq. 'mOD1' .or.
     .        line(1:4) .eq. 'mod1'      ) then
c
         now_reading_strips=.false.
         now_reading_dem1=.false.
         now_reading_dem2=.false.
         now_reading_demm=.false.
         now_reading_demd=.true.
         hit_EOD=.false.
         found_run=.false.
c
c remaining fields are length of module data, three angles, and z.
c I want to treat this like dem2 for the purposes of the display.
c
c CAREFUL!! the digit in "read(line(x:)..." must be 1 greater than the digit
c in the "if(line(1:y)..." statement above.
c the colon in the line(1:y)
         read(line(5:), *, iostat=io_err) num_demd_hits_read,
     .        phi_read_demd, psi_read_demd, theta_read_demd,
     .        z_read_demd
     .        ,number_cols_read_demd, number_rows_read_demd
c
c check that it went OK.
         if(io_err .ne. 0) then
c
c            print *,
c     .           ' hit problem reading marebo header record'
c            print *,' iostat returned was... ',io_err
c
c
            call event_display_write_message(
     .         ' ...problem reading module header record')
c
            ireturn_code=16
            return
            end if
c
c
c load the angles and z's, but only if the z position is non-zero:
         if(z_read_demd .ne. 0.) then
            num_demd_hits=num_demd_hits_read
            phidemd=phi_read_demd
            psidemd=psi_read_demd
            thetademd=theta_read_demd
            xplane_z0(ipldemd)=z_read_demd
            yplane_z0(ipldemd)=z_read_demd
            number_cols_demd=number_cols_read_demd
            number_rows_demd=number_rows_read_demd
            end if
c
c
c now get the next line of data:
         go to 200
c
c
c
c end-of-event marker?
c
      else if(line(1:3) .eq. 'EOD' .or.
     .        line(1:3) .eq. 'Eod' .or.
     .        line(1:3) .eq. 'eOD' .or.
     .        line(1:3) .eq. 'eod' ) then
c
         now_reading_strips=.false.
         now_reading_dem1=.false.
         now_reading_dem2=.false.
         now_reading_demm=.false.
         now_reading_demd=.false.
         hit_EOD=.true.
         found_run=.false.
c
c
c increment the events-read counter:
         ievents_read=ievents_read+1
c
c
c now see which pixel detectors were actually in place, in order to decide
c how to map the angle-changing buttons. I can only have at most two 
c detectors' buttons displayed. Use the value of z_read_... to see if
c the detector exists.
c
         iset=0
         ib1=2
         ib2=ib1+1
         ib3=ib2+1
         map_button(new_dem1_phi_button)=0
         map_button(new_dem1_psi_button)=0
         map_button(new_dem1_theta_button)=0
         map_button(new_dem2_phi_button)=0
         map_button(new_dem2_psi_button)=0
         map_button(new_dem2_theta_button)=0
         map_button(new_demm_phi_button)=0
         map_button(new_demm_psi_button)=0
         map_button(new_demm_theta_button)=0
         map_button(new_demd_phi_button)=0
         map_button(new_demd_psi_button)=0
         map_button(new_demd_theta_button)=0
c
c first trio of buttons:
         if(z_read_dem1 .ne. 0.) then 
            map_button(new_dem1_phi_button)=ib1
            map_button(new_dem1_psi_button)=ib2
            map_button(new_dem1_theta_button)=ib3
            iset=1
c
            else if(z_read_dem2 .ne. 0.) then 
            map_button(new_dem2_phi_button)=ib1
            map_button(new_dem2_psi_button)=ib2
            map_button(new_dem2_theta_button)=ib3
            iset=2
c
            else if(z_read_demm .ne. 0.) then 
            map_button(new_demm_phi_button)=ib1
            map_button(new_demm_psi_button)=ib2
            map_button(new_demm_theta_button)=ib3
            iset=3
c
            else if(z_read_demd .ne. 0.) then 
            map_button(new_demd_phi_button)=ib1
            map_button(new_demd_psi_button)=ib2
            map_button(new_demd_theta_button)=ib3
            iset=4
c
            end if
c
c next trio of buttons:            
         ib1=ib3+1
         ib2=ib1+1
         ib3=ib2+1

         if(iset .eq. 1 .and. z_read_dem2 .ne. 0.) then 
            map_button(new_dem2_phi_button)=ib1
            map_button(new_dem2_psi_button)=ib2
            map_button(new_dem2_theta_button)=ib3
c
            else if((iset.eq.1 .or. iset.eq.2) .and. 
     .           z_read_demm .ne. 0.) then 
            map_button(new_demm_phi_button)=ib1
            map_button(new_demm_psi_button)=ib2
            map_button(new_demm_theta_button)=ib3
c
            else if((iset.eq.1 .or. iset.eq.2 .or. iset.eq.3) .and. 
     .           z_read_demd .ne. 0.) then 
            map_button(new_demd_phi_button)=ib1
            map_button(new_demd_psi_button)=ib2
            map_button(new_demd_theta_button)=ib3
c
            end if
c
c 
c now check to see if we found the number of lines of data we expected:
c strip data...
         if(ifound_strip_hits_total .ne. num_strip_hits_total) then
c            print *,' expected ', num_strip_hits_total, ' but found ',
c     .      ifound_strip_hits_total
c
c                          11111111112222222222333333333344444444445
c                 12345678901234567890123456789012345678901234567890
            text=' ...number of hit strips disagrees with header:   '
     .         //'found xxxxxx, expected yyyyyy'
c
            write(text(57:62), '(i6)') ifound_strip_hits_total 
            write(text(74:79), '(i6)') num_strip_hits_total
c
            call event_display_write_message(text(1:79))
c
            ireturn_code=-13
            end if
c     
c dem1 data...
         if(ifound_dem1_hits .ne. num_dem1_hits) then
c            print *,' expected ', num_dem1_hits, ' but found ',
c     .      ifound_dem1_hits
c
c                          11111111112222222222333333333344444444445
c                 12345678901234567890123456789012345678901234567890
            text=' ..number of dem1 pixels disagrees with header:   '
     .         //'found xxxxxx, expected yyyyyy'
c
            write(text(57:62), '(i6)') ifound_dem1_hits 
            write(text(74:79), '(i6)') num_dem1_hits
c
            call event_display_write_message(text(1:79))
c
            ireturn_code=-14
            end if
c     
c dem2 data...
         if(ifound_dem2_hits .ne. num_dem2_hits) then
c            print *,' expected ', num_dem2_hits, ' but found ',
c     .      ifound_dem2_hits
c 
c                          11111111112222222222333333333344444444445
c                 12345678901234567890123456789012345678901234567890
            text=' ..number of dem2 pixels disagrees with header:   '
     .         //'found xxxxxx, expected yyyyyy'
c
            write(text(57:62), '(i6)') ifound_dem2_hits 
            write(text(74:79), '(i6)') num_dem2_hits
c
            call event_display_write_message(text(1:79))
c
            ireturn_code=-15
            end if
c          
c
c marebo data...
         if(ifound_demm_hits .ne. num_demm_hits) then
c            print *,' expected ', num_demm_hits, ' but found ',
c     .      ifound_demm_hits
c 
c                          11111111112222222222333333333344444444445
c                 12345678901234567890123456789012345678901234567890
            text=' ..nmber of marebo pixels disagrees wth header:   '
     .         //'found xxxxxx, expected yyyyyy'
c
            write(text(57:62), '(i6)') ifound_demm_hits 
            write(text(74:79), '(i6)') num_demm_hits
c
            call event_display_write_message(text(1:79))
c
            ireturn_code=-16
            end if
c          
c
c module data...
         if(ifound_demd_hits - number_shared_hits .ne. 
     .           num_demd_hits) then
c            print *,' expected ', num_demd_hits, ' but found ',
c     .      ifound_demd_hits
c 
c                          11111111112222222222333333333344444444445
c                 12345678901234567890123456789012345678901234567890
            text=' ..nmber of module pixels disagrees wth header:   '
     .         //'found xxxxxx, expected yyyyyy'
c
            write(text(57:62), '(i6)') 
     .           ifound_demd_hits - number_shared_hits
            write(text(74:79), '(i6)') num_demd_hits
c
            call event_display_write_message(text(1:79))
c
            ireturn_code=-26
            end if
c          
c
c close the event data file:
cc         call event_display_write_message(
cc     .           'found EOD record, so closing data file')
         close(lun_data)
c
c
c since we're done reading this event's raw data, delete the file so 
c that Thierry can tell that he can write another one for us.
         if(delete_file_when_finished) then
c
c system call to delete file...
            istat=0
ccc            istat=system('rm '//file_data)
            call system('rm '//file_data)
c
c worked OK?
            if(istat .ne. 0) then
c no...
c               print *,' bad status returned by system call',
c     .              ' to delete ',file_data
c               print *,' status was ',istat
c      
               call event_display_write_message(
     .         ' ...problem deleting data file when finished')
c
               ireturn_code=7
               end if
c
            end if
c
         return
c
c
c
c run number, event number marker?
c
      else if(line(1:3) .eq. 'RUN' .or.
     .        line(1:3) .eq. 'Run' .or.
     .        line(1:3) .eq. 'rUN' .or.
     .        line(1:3) .eq. 'run' ) then
c
         now_reading_strips=.false.
         now_reading_dem1=.false.
         now_reading_dem2=.false.
         now_reading_demm=.false.
         now_reading_demd=.false.
         hit_EOD=.false.
         found_run=.true.
c
c
c remaining fields are run number and event number.
c
c CAREFUL!! the digit in "read(line(x:)..." must be 1 greater than the digit
c in the "if(line(1:y)..." statement above.
c the colon in the line(1:y)
         read(line(4:), *, iostat=io_err) irun_number,  ievent_number
c
c check that it went OK.
         if(io_err .ne. 0) then
c
c            print *,
c     .           ' hit problem reading run number header record'
c            print *,' iostat returned was... ',io_err
c            print *,' irun_number,  ievent_number ',
c     .           irun_number,  ievent_number
            call event_display_write_message(
     .           ' ...problem reading run number header')
c
            ireturn_code=-10
c get the next line, instead of trashing the entire event...
            go to 200
            end if
c
c tell the user what we found:
         write(text(1:25), '(4hrun ,i6,8h  event ,i7)') 
     .           irun_number,  ievent_number
         call event_display_write_message(text(1:25))
c
c now get the next line of data:
         go to 200
c
         end if
c
c
c
c ******************* (check to see that we know what kind of data we have)
c
c
c we only end up here if the line wasn't recognized as the start of a new
c detector's data, or as an end-of-data marker, or as the run number/event
c number specifier. If we don't know what kind of detector we're dealing 
c with at this point, there's been an error.
c
      if(.not. now_reading_strips .and.
     .   .not. now_reading_dem1   .and.
     .   .not. now_reading_dem2   .and.
     .   .not. now_reading_demm   .and.
     .   .not. now_reading_demd ) then
c
c         print *,' tried reading detector data before finding header'
c
         call event_display_write_message(
     .   ' ... tried reading detector data before finding header')
c
         ireturn_code=8
         return
         end if
c
c
c ******************* (handle strip data)
c
c
      if(now_reading_strips) then
c
c strip data: sirocco number, strip number, and amplitude. first strip
c is 0, not 1.
         read(line(1:), *, iostat=io_err) isir, istrip, iamp
c
c
c check that format was OK.
         if(io_err .ne. 0) then
c
c            print *,
c     .           ' problem reading strip data: file line ',
c     .           lines_read_from_file
c            print *,' bad data had sirocco, strip, amplitude as ',
c     .           isir, istrip, iamp
c
            call event_display_write_message(
     .      ' ... strip data problem')
c
c
            ireturn_code=-9
c get the next line, instead of just quiting...
            go to 200
            end if
c
c
c data are OK... determine whether x or y view...
         ifound_strip_hits_total=ifound_strip_hits_total + 1
         if(isir .le. 4) then
            iview=1
            iplane=isir
            else
            iview=2
            iplane=isir-4
            end if
c
c
c check for legal plane and strip number:
         if(istrip .lt. 0 .or. istrip .gt. number_strips-1 .or.
     .      iplane .lt. 1  .or. iplane .gt. 4) then
c
ccc            print *,' bad sirocco, strip and/or plane: ',
ccc     .           istrip, iplane
c
ccc            call event_display_write_message(
ccc     .      ' ... strip data problem')
c
            ireturn_code=-9
c get the next line, instead of just quiting...
            go to 200
            end if
c
c
c here if it's fine, excellent, marvelous data...
         ifound_strip_hits(iview,iplane)=
     .           ifound_strip_hits(iview, iplane) + 1
         num_strip_hits(iview,iplane)=
     .           num_strip_hits(iview, iplane) + 1
         istrip_number_read(ifound_strip_hits(iview,iplane), 
     .                      iview, iplane)=istrip
         istrip_adc_read(ifound_strip_hits(iview,iplane), 
     .                      iview, iplane)=iamp
c
c
c we're done, so get the next line of data...
         go to 200
         end if
c
c
c ******************* (handle dem1 data)
c
c
      if(now_reading_dem1) then
c
c pixel demonstrator 1 data: column, row, beam crossing number, TOT.
c columns, rows start at 0, not 1.
         read(line(1:), *, iostat=io_err) icol, irow, ibc, itot
c
c
c check that format was OK.
         if(io_err .ne. 0) then
c
c            print *,
c     .           ' problem reading dem1 data: file line ',
c     .           lines_read_from_file
c            print *,' bad data had column, row, beamcrossing, tot ',
c     .           icol, irow, ibc, itot
c
            call event_display_write_message(
     .      ' ... dem1 data problem')

c
            ireturn_code=-11
c get the next line, instead of just quiting...
            go to 200
            end if
c
c
c data read OK... check for legal plane and strip number:
         ifound_dem1_hits=ifound_dem1_hits + 1
         if(icol .lt. 0 .or. icol .gt. number_cols_dem1-1 .or.
     .      irow .lt. 0 .or. irow .gt. number_rows_dem1-1 .or.
     .      ibc  .lt. 0 .or. ibc  .gt. 16                 .or.
     .      itot .lt. 0 .or. itot .gt. 1023) then
c
c            print *,' bad dem1 data: icol, irow, ibc, itot are',
c     .           icol, irow, ibc, itot
c
ccc            call event_display_write_message(
ccc     .      ' ... dem1 data problem')
c
            ireturn_code=-11
c get the next line, instead of just quiting...
            go to 200
            end if
c
c
c ah, such fine data we have!
         idem1_col_read(ifound_dem1_hits)=icol
         idem1_row_read(ifound_dem1_hits)=irow
         idem1_beam_crossing(ifound_dem1_hits)=ibc
         idem1_tot_read(ifound_dem1_hits)=itot
c
c
c we're done, so get the next line of data...
         go to 200
         end if
c
c
c ******************* (handle dem2 data)
c
c
      if(now_reading_dem2) then
c
c pixel demonstrator 2 data: column, row, beam crossing number, TOT.
c columns, rows start at 0, not 1.
         read(line(1:), *, iostat=io_err) icol, irow, ibc, itot
c
c
c check that format was OK.
         if(io_err .ne. 0) then
c
c            print *,
c     .           ' problem reading dem2 data: file line ',
c     .           lines_read_from_file
c            print *,' bad data had column, row, beamcrossing, tot ',
c     .           icol, irow, ibc, itot
c
            call event_display_write_message(
     .      ' ... dem2 data problem')
c
            ireturn_code=-12
c get the next line, instead of just quiting...
            go to 200
            end if
c
c
c data read OK... check for legal plane and strip number:
         ifound_dem2_hits=ifound_dem2_hits + 1
         if(icol .lt. 0 .or. icol .gt. number_cols_dem2-1 .or.
     .      irow .lt. 0 .or. irow .gt. number_rows_dem2-1 .or.
     .      ibc  .lt. 0 .or. ibc  .gt. 16                 .or.
     .      itot .lt. 0 .or. itot .gt. 1023) then
c
ccc            print *,' bad dem2 data: icol, irow, ibc, itot are',
ccc     .           icol, irow, ibc, itot
c
ccc            call event_display_write_message(
ccc     .      ' ... dem2 data problem')
c
            ireturn_code=-12
c get the next line, instead of just quiting...
            go to 200
            end if
c
c
c ah, such exquisite data we have!
         idem2_col_read(ifound_dem2_hits)=icol
         idem2_row_read(ifound_dem2_hits)=irow
         idem2_beam_crossing(ifound_dem2_hits)=ibc
         idem2_tot_read(ifound_dem2_hits)=itot
c
c
c we're done, so get the next line of data...
         go to 200
         end if
c
c
c ******************* (handle marebo data)
c
c
      if(now_reading_demm) then
c
c Marebo data: column, row, beam crossing number, TOT.
c columns, rows start at 0, not 1.
         read(line(1:), *, iostat=io_err) icol, irow, ibc, itot
c
c
c check that format was OK.
         if(io_err .ne. 0) then
c
c            print *,
c     .           ' problem reading demm data: file line ',
c     .           lines_read_from_file
c            print *,' bad data had column, row, beamcrossing, tot ',
c     .           icol, irow, ibc, itot
c
            call event_display_write_message(
     .      ' ... demm data problem')
c
            ireturn_code=-17
c get the next line, instead of just quiting...
            go to 200
            end if
c
c
c data read OK... check for legal plane and strip number:
         ifound_demm_hits=ifound_demm_hits + 1
         if(icol .lt. 0 .or. icol .gt. number_cols_demm-1 .or.
     .      irow .lt. 0 .or. irow .gt. number_rows_demm-1 .or.
     .      ibc  .lt. 0 .or. ibc  .gt. 16                 .or.
     .      itot .lt. 0 .or. itot .gt. 1023) then
c
ccc            print *,' bad demm data: icol, irow, ibc, itot are',
ccc     .           icol, irow, ibc, itot
c
ccc            call event_display_write_message(
ccc     .      ' ... demm data problem')
c
            ireturn_code=-17
c get the next line, instead of just quiting...
            go to 200
            end if
c
c
c ah, such exquisite data we have!
         idemm_col_read(ifound_demm_hits)=icol
         idemm_row_read(ifound_demm_hits)=irow
         idemm_beam_crossing(ifound_demm_hits)=ibc
         idemm_tot_read(ifound_demm_hits)=itot
c
c
c we're done, so get the next line of data...
         go to 200
         end if
c
c ******************* (handle module data)
c
c
      if(now_reading_demd) then
c
c pixel module data: column, row, beam crossing number, TOT.
c columns, rows start at 0, not 1.
         read(line(1:), *, iostat=io_err) icol, irow, ibc, itot
c
c
c check that format was OK.
         if(io_err .ne. 0) then
c
c            print *,
c     .           ' problem reading demd data: file line ',
c     .           lines_read_from_file
c            print *,' bad data had column, row, beamcrossing, tot ',
c     .           icol, irow, ibc, itot
c
            call event_display_write_message(
     .      ' ... demd data problem')
c
            ireturn_code=-22
c get the next line, instead of just quiting...
            go to 200
            end if
c
c
c data read OK... check for legal plane and strip number:
         ifound_demd_hits=ifound_demd_hits + 1
         if(icol .lt. 0 .or. icol .gt. number_cols_demd-1 .or.
     .      irow .lt. 0 .or. irow .gt. number_rows_demd-1 .or.
     .      ibc  .lt. 0 .or. ibc  .gt. 16                 .or.
     .      itot .lt. 0 .or. itot .gt. 1023) then
c
ccc            print *,' bad demd data: icol, irow, ibc, itot are',
ccc     .           icol, irow, ibc, itot
c
ccc            call event_display_write_message(
ccc     .      ' ... demd data problem')
c
            ireturn_code=-22
c get the next line, instead of just quiting...
            go to 200
            end if
c
c
c ah, such exquisite data we have!
         idemd_col_read(ifound_demd_hits)=icol
         idemd_row_read(ifound_demd_hits)=irow
         idemd_beam_crossing(ifound_demd_hits)=ibc
         idemd_tot_read(ifound_demd_hits)=itot
c
c detector cells 160 - 163 share readout with cells 153, 155, 157, 159
c respectively. By hand, we'll have to mess with how we display this.
c
c
c we're done, so get the next line of data...
         go to 200
         end if
c
c
c
      end